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XCCDF
Application Layer Gateway Security Requirements Guide
Profiles
II - Mission Support Classified
II - Mission Support Classified
An XCCDF Profile
Details
Items
Prose
155 rules organized in 155 groups
SRG-NET-000015
1 Rule
The ALG must enforce approved authorizations for logical access to information and system resources by employing identity-based, role-based, and/or attribute-based security policies.
Medium Severity
Successful authentication must not automatically give an entity access to an asset or security boundary. The lack of authorization-based access control could result in the immediate compromise and unauthorized access to sensitive information. All DoD systems must be properly configured to incorporate access control methods that do not rely solely on authentication for authorized access. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset. Information systems use access control policies and enforcement mechanisms to implement this requirement. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Access control policies include identity-based policies, role-based policies, and attribute-based policies. Access enforcement mechanisms include access control lists, access control matrices, and cryptography. ALGs must use these policies and mechanisms to control access on behalf of the application for which it is acting as intermediary.
SRG-NET-000018
1 Rule
The ALG must enforce approved authorizations for controlling the flow of information within the network based on attribute- and content-based inspection of the source, destination, headers, and/or content of the communications traffic.
Medium Severity
Information flow control regulates where information is allowed to travel within a network. The flow of all network traffic must be monitored and controlled so it does not introduce any unacceptable risk to the network infrastructure or data. Information flow control policies and enforcement mechanisms are commonly employed by organizations to control the flow of information between designated sources and destinations (e.g., networks, individuals, devices) within information systems. Examples of information flow control restrictions include keeping export controlled information from being transmitted in the clear to the Internet or blocking information marked as classified but is being transported to an unapproved destination. ALGs enforce approved authorizations by employing security policy and/or rules that restrict information system services, provide packet filtering capability based on header or protocol information and/or message filtering capability based on data content (e.g., implementing key word searches or using document characteristics).
SRG-NET-000019
1 Rule
The ALG must restrict or block harmful or suspicious communications traffic by controlling the flow of information between interconnected networks based on attribute- and content-based inspection of the source, destination, headers, and/or content of the communications traffic.
Medium Severity
Information flow control regulates where information is allowed to travel within a network and between interconnected networks. Blocking or restricting detected harmful or suspicious communications between interconnected networks enforces approved authorizations for controlling the flow of traffic. This requirement applies to the flow of information between the ALG when used as a gateway or boundary device which allows traffic flow between interconnected networks of differing security policies. The ALG is installed and configured such that it restricts or blocks information flows based on guidance in the PPSM regarding restrictions for boundary crossing for ports, protocols and services. Information flow restrictions may be implemented based on attribute- and content-based inspection of the source, destination, headers, and/or content of the communications traffic. The ALG must be configured with policy filters (e.g., security policy, rules, and/or signatures) that restrict or block information system services; provide a packet-filtering capability based on header information; and/or perform message-filtering based on message content. The policy filters used depends upon the type of application gateway (e.g., web, email, or TLS).
SRG-NET-000019
1 Rule
The ALG must immediately use updates made to policy enforcement mechanisms such as policy filters, rules, signatures, and analysis algorithms for gateway and/or intermediary functions.
Medium Severity
Information flow policies regarding dynamic information flow control include, for example, allowing or disallowing information flows based on changes to the PPSM CAL, vulnerability assessments, or mission conditions. Changing conditions include changes in the threat environment and detection of potentially harmful or adverse events. Changes to the ALG must take effect when made by an authorized administrator and the new configuration is put in place or committed, including upon restart or the application or reboot of the system. With some devices, the changes take effect as the configuration is changed, while with others, the new configuration must be submitted to the device. In any case, the behavior of the ALG must immediately be affected to reflect the configuration change.
SRG-NET-000019
1 Rule
The ALG that is part of a CDS must apply information flow control to data transferred between security domains by means of a policy filter which consists of a set of hardware and/or software.
Medium Severity
Information flow control regulates where information is allowed to travel within a network and between interconnected networks. The flow of all network traffic must be monitored and controlled so it does not introduce any unacceptable risk to the network infrastructure or data. Apply information flow control to data transferred between security domains by means of a set of hardware and/or software, collectively known as the "filter". Flow control includes the inspection, sanitization, and/or rejection of data from one security domain prior to transfer of data to a different security domain. For an access type CDS, the remote desktop architecture provides the capability for a user to have access from a single device to computing platforms, applications, or data residing on multiple different security domains; while preventing any information flow between the different security domains.
SRG-NET-000021
1 Rule
The ALG that is part of a CDS must allow privileged administrators to enable/disable all security policy filters used to enforce information flow control.
Medium Severity
A crucial part of any information flow control solution is the ability to enable and disable policy filters in order to respond to changes in organizational security posture and mission conditions. This is not a requirement to restrict the capability to privileged administrators, but rather to ensure there is some means of enabling/disabling policy filters (e.g., command line or user console). Policy filters enforce organizational security policy as it pertains to controlling data flow. Security policy filters can address data structures and content. These filters may include dirty word filters, file type checking filters, structured data filters, unstructured data filters, metadata content filters, and hidden content filters.
SRG-NET-000022
1 Rule
The ALG that is part of a CDS must allow privileged administrators to configure and make changes to all security policy filters that are used to enforce information flow control.
Medium Severity
The use of security policy filters provides protection for the confidentiality of data by restricting the flow of data. The capability to configure policy filters allows the ALG to enforce more granular security policies to meet complex and changing mission needs. Policy filters enforce organizational security policy as it pertains to controlling data flow. Security policy filters can address data structures and content. These filters may include dirty word filters, file type checking filters, structured data filters, unstructured data filters, metadata content filters, and hidden content filters. The cross domain solution must be configured to restrict management access according to the privilege level the user has been granted. Authorization to configure security policies requires the highest privilege level. This control requires the device have the capability for privileged administrators to configure security filters and to reconfigure these policies as needed to support changes in security policy.
SRG-NET-000029
1 Rule
The ALG that is part of a CDS must enforce dynamic traffic flow control based on organization-defined policies.
Medium Severity
Information flow policies regarding dynamic information flow control include allowing or disallowing information flows based on changing conditions or mission/operational considerations. Changing conditions include changes in organizational risk tolerance due to changes in the immediacy of mission/business needs, changes in the threat environment, and detection of potentially harmful or adverse events. Organization-defined policies for CDS systems depend on the environment, data, and security boundaries. Organizations implementing CDS must follow the DoD-required process of testing, baselining, and risk assessment to ensure the rigor and accuracy necessary to rely upon a CDS for cross domain security. Enforcement occurs in boundary protection devices that employ rule sets or establish configuration settings that restrict information system services, provide a packet filtering capability based on header information, or provide a message filtering capability based on message content (e.g., implementing key word searches or using document characteristics). This requirement is primarily used by organizations with cross domain solution needs. These solutions require advanced filtering techniques and flow enforcement mechanisms, such as high-assurance guards. Dynamic traffic flow control mechanisms are generally not available in commercial off-the-shelf information technology products.
SRG-NET-000032
1 Rule
The ALG that is part of a CDS must enforce organization-defined one-way information flows using hardware mechanisms.
Medium Severity
Information flow control regulates where information is allowed to travel within a network and between interconnected networks. The flow of all network traffic must be monitored and controlled so it does not introduce any unacceptable risk to the network infrastructure or data. For cross domain solutions, use of hardware enforced flow direction is preferable in high risk environments but is not mandatory. Do not enable any connections between security domains beyond the specified one-way flow. Organization-defined one-way information flows using hardware mechanisms used as part of a CDS system depends on the environment, data, and security boundaries. Organizations implementing CDS must follow the DoD-required process of testing, baselining, and risk assessment to ensure the rigor and accuracy necessary to rely upon a CDS for cross domain security.
SRG-NET-000033
1 Rule
The ALG that is part of a CDS must enforce information flow control using organization-defined security policy filters as a basis for flow control decisions for organization-defined information flows.
Medium Severity
The use of security policy filters provides protection for the confidentiality of data by restricting the flow of data. Configure organization-defined specific filters and their order of execution for each information flow. For example, security policy filters may include data content filtering rules that monitor for and block specific words (e.g., key word indicators such as terms associated with classified mission), enumerated values, or data value ranges, and hidden content. Organization-defined security policy filter and organization-defined information flows used as part of a CDS system depend on the environment, data, and security boundaries. Organizations implementing CDS must follow the DoD-required process of testing, baselining, and risk assessment to ensure the rigor and accuracy necessary to rely upon a CDS for cross domain security.
SRG-NET-000041
1 Rule
The ALG providing user access control intermediary services must display the Standard Mandatory DoD-approved Notice and Consent Banner before granting access to the network.
Medium Severity
Display of a standardized and approved use notification before granting access to the network ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist. This requirement applies to network elements that have the concept of a user account and have the logon function residing on the network element. The banner must be formatted in accordance with DTM-08-060. Use the following verbiage for network elements that can accommodate banners of 1300 characters: "You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details." Use the following verbiage for operating systems that have severe limitations on the number of characters that can be displayed in the banner: "I've read & consent to terms in IS user agreem't." This policy only applies to ALGs (e.g., identity management or authentication gateways) that provide user account services as part of the intermediary services.
SRG-NET-000042
1 Rule
The ALG providing user access control intermediary services must retain the Standard Mandatory DoD-approved Notice and Consent Banner on the screen until users acknowledge the usage conditions and take explicit actions to log on for further access.
Medium Severity
The banner must be acknowledged by the user prior to allowing the user access to the network. This provides assurance that the user has seen the message and accepted the conditions for access. If the consent banner is not acknowledged by the user, DoD will not be in compliance with system use notifications required by law. To establish acceptance of the application usage policy, a click-through banner at application logon is required. The network element must prevent further activity until the user executes a positive action to manifest agreement by clicking on a box indicating "OK". This policy only applies to gateways (e.g., identity management or authentication gateways) that provide user account services as part of the intermediary services.
SRG-NET-000043
1 Rule
The ALG providing user access control intermediary services for publicly accessible applications must display the Standard Mandatory DoD-approved Notice and Consent Banner before granting access to the system.
Medium Severity
Display of a standardized and approved use notification before granting access to the publicly accessible network element ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist. This requirement applies to network elements that have the concept of a user account and have the logon function residing on the network element. The banner must be formatted in accordance with DTM-08-060. Use the following verbiage for network elements that can accommodate banners of 1300 characters: "You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details." Use the following verbiage for operating systems that have severe limitations on the number of characters that can be displayed in the banner: "I've read & consent to terms in IS user agreem't." This policy only applies to gateways (e.g., identity management or authentication gateways) that provide user account services as part of the intermediary services off-loaded from the application. Publicly access systems are used in DoD to provide benefit information, pay information, or public services. There may also be self-registration and authorization services provided by these gateways.
SRG-NET-000053
1 Rule
The ALG providing user access control intermediary services must limit the number of concurrent sessions to an organization-defined number for all accounts and/or account types.
Medium Severity
Network element management includes the ability to control the number of users and user sessions that utilize a network element. Limiting the number of current sessions per user is helpful in limiting risks related to DoS attacks. This requirement addresses concurrent sessions for information system accounts and does not address concurrent sessions by single users via multiple system accounts. The maximum number of concurrent sessions must be the same as the requirements specified for the application for which it serves as intermediary. This policy only applies to application gateways/firewalls (e.g., identity management or authentication gateways) that provide user account services as part of the intermediary services.
SRG-NET-000061
1 Rule
The ALG providing intermediary services for remote access communications traffic must ensure inbound and outbound traffic is monitored for compliance with remote access security policies.
Medium Severity
Automated monitoring of remote access traffic allows organizations to detect cyber attacks and also ensure ongoing compliance with remote access policies by inspecting connection activities of remote access capabilities. Remote access methods include both unencrypted and encrypted traffic (e.g., web portals, web content filter, TLS and webmail). With inbound TLS inspection, the traffic must be inspected prior to being allowed on the enclave's web servers hosting TLS or HTTPS applications. With outbound traffic inspection, traffic must be inspected prior to being forwarded to destinations outside of the enclave, such as external email traffic.
SRG-NET-000062
1 Rule
The ALG providing intermediary services for remote access communications traffic must use encryption services that implement NIST FIPS-validated cryptography to protect the confidentiality of remote access sessions.
Medium Severity
Without confidentiality protection mechanisms, unauthorized individuals may gain access to sensitive information via a remote access session. Remote access is access to DoD nonpublic information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network. Remote access methods include broadband and wireless connections. Remote access methods include, for example, proxied remote encrypted traffic (e.g., TLS gateways, web content filters, and webmail proxies). Encryption provides a means to secure the remote connection so as to prevent unauthorized access to the data traversing the remote access connection, thereby providing a degree of confidentiality. The encryption strength of the mechanism is selected based on the security categorization of the information. This requirement applies to ALGs providing remote access proxy services as part of its intermediary services (e.g., OWA or TLS gateway).
SRG-NET-000062
1 Rule
The ALG that stores secret or private keys must use FIPS-approved key management technology and processes in the production and control of private/secret cryptographic keys.
Medium Severity
Private key data is used to prove that the entity presenting a public key certificate is the certificate's rightful owner. Compromise of private key data allows an adversary to impersonate the key holder. Private key data associated with software certificates, including those issued to an ALG, is required to be generated and protected in at least a FIPS 140-2 Level 1 validated cryptographic module.
SRG-NET-000062
1 Rule
The ALG that provides intermediary services for TLS must be configured to comply with the required TLS settings in NIST SP 800-52.
Medium Severity
SP 800-52 provides guidance on using the most secure version and configuration of the TLS/SSL protocol. Using older unauthorized versions or incorrectly configuring protocol negotiation makes the gateway vulnerable to known and unknown attacks which exploit vulnerabilities in this protocol. This requirement applies to TLS gateways (also known as SSL gateways) and is not applicable to VPN devices. Application protocols such as HTTPS and DNSSEC use TLS as the underlying security protocol thus are in scope for this requirement. NIS SP 800-52 provides guidance. SP 800-52 sets TLS version 1.1 as a minimum version, thus all versions of SSL are not allowed (including for client negotiation) either on DoD-only or on public facing servers.
SRG-NET-000063
1 Rule
The ALG providing intermediary services for remote access communications traffic must use NIST FIPS-validated cryptography to protect the integrity of remote access sessions.
Medium Severity
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. Remote access is access to DoD-nonpublic information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network. Remote access methods include broadband and wireless connections. Remote access methods include, for example, proxied remote encrypted traffic (e.g., TLS gateways, web content filters, and webmail proxies). Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash. This requirement applies to ALGs providing remote access proxy services as part of its intermediary services (e.g., OWA or TLS gateway).
SRG-NET-000074
1 Rule
The ALG must produce audit records containing information to establish what type of events occurred.
Medium Severity
Without establishing what type of event occurred, it would be difficult to establish, correlate, and investigate the events leading up to an outage or attack. Audit record content that may be necessary to satisfy this requirement includes, for example, event descriptions, success/fail indications, filenames involved, and access control or flow control rules invoked. Associating event types with detected events in the gateway logs provides a means of investigating an attack, recognizing resource utilization or capacity thresholds, or identifying an improperly configured network element. This requirement does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000075
1 Rule
The ALG must produce audit records containing information to establish when (date and time) the events occurred.
Medium Severity
Without establishing when events occurred, it is impossible to establish, correlate, and investigate the events leading up to an outage or attack. In order to compile an accurate risk assessment, and provide forensic analysis of network traffic patterns, it is essential for security personnel to know when flow control events occurred within the infrastructure. Associating event types with detected events in the network audit logs provides a means of investigating an attack, recognizing resource utilization or capacity thresholds, or identifying an improperly configured network element. This requirement does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000076
1 Rule
The ALG must produce audit records containing information to establish where the events occurred.
Medium Severity
Without establishing where events occurred, it is impossible to establish, correlate, and investigate the events leading up to an outage or attack. In order to compile an accurate risk assessment, and provide forensic analysis, it is essential for security personnel to know where events occurred, such as network element components, modules, device identifiers, node names, and functionality. Associating information about where the event occurred within the network provides a means of investigating an attack, recognizing resource utilization or capacity thresholds, or identifying an improperly configured network element. This requirement does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000077
1 Rule
The ALG must produce audit records containing information to establish the source of the events.
Medium Severity
Without establishing the source of the event, it is impossible to establish, correlate, and investigate the events leading up to an outage or attack. In order to compile an accurate risk assessment and provide forensic analysis, security personnel need to know the source of the event. In addition to logging where events occur within the network, the audit records must also identify sources of events such as IP addresses, processes, and node or device names. This requirement does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000078
1 Rule
The ALG must produce audit records containing information to establish the outcome of the events.
Medium Severity
Without information about the outcome of events, security personnel cannot make an accurate assessment as to whether an attack was successful or if changes were made to the security state of the network. Event outcomes can include indicators of event success or failure and event-specific results (e.g., the security state of the network after the event occurred). As such, they also provide a means to measure the impact of an event and help authorized personnel to determine the appropriate response. This requirement does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000079
1 Rule
The ALG must generate audit records containing information to establish the identity of any individual or process associated with the event.
Medium Severity
Without information that establishes the identity of the subjects (i.e., users or processes acting on behalf of users) associated with the events, security personnel cannot determine responsibility for the potentially harmful event. Associating information about where the event occurred within the network provides a means of investigating an attack, recognizing resource utilization or capacity thresholds, or identifying an improperly configured network element. This requirement does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000088
1 Rule
The ALG must send an alert to, at a minimum, the ISSO and SCA when an audit processing failure occurs.
Medium Severity
It is critical for the appropriate personnel to be aware if a system is at risk of failing to process audit logs as required. Without this notification, the security personnel may be unaware of an impending failure of the audit capability and system operation may be adversely affected. Audit processing failures include software/hardware errors, failures in the audit capturing mechanisms, and audit storage capacity being reached or exceeded. Possible audit processing failures also include the inability of ALG to write to the central audit log. This requirement applies to each audit data storage repository (i.e., distinct information system component where audit records are stored), the centralized audit storage capacity of organizations, (i.e., all audit data storage repositories combined), or both. This does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000098
1 Rule
The ALG must protect audit information from unauthorized read access.
Medium Severity
Auditing and logging are key components of any security architecture. Logging the actions of specific events provides a means to investigate an attack, recognize resource utilization or capacity thresholds, or to simply identify an improperly configured network element. Thus, it is imperative that the collected log data from the various network elements, as well as the auditing tools, be secured and can only be accessed by authorized personnel. This does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000099
1 Rule
The ALG must protect audit information from unauthorized modification.
Medium Severity
If audit data were to become compromised, then forensic analysis and discovery of the true source of potentially malicious system activity is impossible to achieve. To ensure the veracity of audit data, the information system and/or the application must protect audit information from unauthorized modification. This requirement can be achieved through multiple methods, which will depend upon system architecture and design. Some commonly employed methods include ensuring log files receive the proper file system permissions, and limiting log data locations. Audit information includes all information (e.g., audit records, audit settings, and audit reports) needed to successfully audit information system activity. This does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000100
1 Rule
The ALG must protect audit information from unauthorized deletion.
Medium Severity
If audit data were to become compromised, then forensic analysis and discovery of the true source of potentially malicious system activity is impossible to achieve. To ensure the veracity of audit data, the information system and/or the application must protect audit information from unauthorized modification. This requirement can be achieved through multiple methods, which will depend upon system architecture and design. Some commonly employed methods include ensuring log files receive the proper file system permissions, and limiting log data locations. Audit information includes all information (e.g., audit records, audit settings, and audit reports) needed to successfully audit information system activity. This requirement does not apply to audit logs generated on behalf of the device itself (device management).
SRG-NET-000101
1 Rule
The ALG must protect audit tools from unauthorized access.
Medium Severity
Protecting audit data also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operation on audit data. Network elements providing tools to interface with audit data will leverage user permissions and roles identifying the user accessing the tools and the corresponding rights the user enjoys in order make access decisions regarding the access to audit tools. Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators. This does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000102
1 Rule
The ALG must protect audit tools from unauthorized modification.
Medium Severity
Protecting audit data also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operation on audit data. Network elements providing tools to interface with audit data will leverage user permissions and roles identifying the user accessing the tools and the corresponding rights the user enjoys in order to make access decisions regarding the modification of audit tools. Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators. This does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000103
1 Rule
The ALG must protect audit tools from unauthorized deletion.
Medium Severity
Protecting audit data also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operation on audit data. Network elements providing tools to interface with audit data will leverage user permissions and roles identifying the user accessing the tools and the corresponding rights the user enjoys in order to make access decisions regarding the deletion of audit tools. Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators. This does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000131
1 Rule
The ALG must not have unnecessary services and functions enabled.
Medium Severity
Information systems are capable of providing a wide variety of functions (capabilities or processes) and services. Some of these functions and services are installed and enabled by default. The organization must determine which functions and services are required to perform the content filtering and other necessary core functionality for each component of the ALG. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. The primary function of an ALG is to provide application specific content filtering and/or proxy services. The ALG application suite may integrate related content filtering and analysis services and tools (e.g., IPS, proxy, malware inspection, black/white lists). Some gateways may also include email scanning, decryption, caching, and DLP services. However, services and capabilities which are unrelated to this primary functionality must not be installed (e.g., DNS, email client or server, FTP server, or web server). Next Generation ALGs (NGFW) and Unified Threat Management (UTM) ALGs integrate functions which have been traditionally separated. These products integrate content filtering features to provide more granular policy filtering. There may be operational drawbacks to combining these services into one device. Another issue is that NGFW and UTM products vary greatly with no current definitive industry standard.
SRG-NET-000131
1 Rule
The ALG must be configured to remove or disable unrelated or unneeded application proxy services.
Medium Severity
Unrelated or unneeded proxy services increase the attack vector and add excessive complexity to the securing of the ALG. Multiple application proxies can be installed on many ALGs. However, proxy types must be limited to related functions. At a minimum, the web and email gateway represent different security domains/trust levels. Organizations should also consider separation of gateways that service the DMZ and the trusted network.
SRG-NET-000132
1 Rule
The ALG must be configured to prohibit or restrict the use of functions, ports, protocols, and/or services, as defined in the PPSM CAL and vulnerability assessments.
Medium Severity
In order to prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types); organizations must disable or restrict unused or unnecessary physical and logical ports/protocols on information systems. ALGs are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. DoD continually assesses the ports, protocols, and services that can be used for network communications. Some ports, protocols or services have known exploits or security weaknesses. Network traffic using these ports, protocols, and services must be prohibited or restricted in accordance with DoD policy. The ALG is a key network element for preventing these non-compliant ports, protocols, and services from causing harm to DoD information systems. The network ALG must be configured to prevent or restrict the use of prohibited ports, protocols, and services throughout the network by filtering the network traffic and disallowing or redirecting traffic as necessary. Default and updated policy filters from the vendors will disallow older version of protocols and applications and will address most known non-secure ports, protocols, and/or services. However, sources for further policy filters are the IAVMs and the PPSM requirements.
SRG-NET-000138
1 Rule
The ALG providing user authentication intermediary services must uniquely identify and authenticate organizational users (or processes acting on behalf of organizational users).
Medium Severity
To assure accountability and prevent unauthenticated access, organizational users must be identified and authenticated to prevent potential misuse and compromise of the system. Organizational users include organizational employees or individuals the organization deems to have equivalent status of employees (e.g., contractors). Organizational users (and any processes acting on behalf of users) must be uniquely identified and authenticated for all accesses except the following. 1) Accesses explicitly identified and documented by the organization. Organizations document specific user actions that can be performed on the information system without identification or authentication. 2) Accesses that occur through authorized use of group authenticators without individual authentication. Organizations may require unique identification of individuals in group accounts (e.g., shared privilege accounts) or for detailed accountability of individual activity. This requirement applies to ALGs that provide user proxy services, including identification and authentication. This service must use the site's directory service (e.g., Active Directory). Directory services must not be installed onto the gateway.
SRG-NET-000138
1 Rule
The ALG providing user access control intermediary services must be configured with a pre-established trust relationship and mechanisms with appropriate authorities (e.g., Active Directory or AAA server) which validate user account access authorizations and privileges.
Medium Severity
User account and privilege validation must be centralized in order to prevent unauthorized access using changed or revoked privileges. ALGs can implement functions such as traffic filtering, authentication, access, and authorization functions based on computer and user privileges. However, the directory service (e.g., Active Directory or LDAP) must not be installed on the ALG, particularly if the gateway resides on the untrusted zone of the Enclave.
SRG-NET-000138
1 Rule
The ALG providing user authentication intermediary services must restrict user authentication traffic to specific authentication server(s).
Medium Severity
User authentication can be used as part of the policy filtering rule sets. Some URLs or network resources can be restricted to authenticated users only. Users are prompted by the application or browser for credentials. Authentication service may be provided by the ALG as an intermediary for the application; however, the authentication credential must be stored in the site's directory services server. This requirement only applies to components where this is specific to the function of the device or has the concept of an organizational user (e.g., proxy capability). This does not apply to authentication for the purpose of configuring the device itself (i.e., device management).
SRG-NET-000140
1 Rule
The ALG providing user authentication intermediary services must use multifactor authentication for network access to non-privileged accounts.
Medium Severity
To assure accountability and prevent unauthenticated access, non-privileged users must utilize multifactor authentication to prevent potential misuse and compromise of the system. Multifactor authentication uses two or more factors to achieve authentication. Factors include: 1) Something you know (e.g., password/PIN), 2) Something you have (e.g., cryptographic, identification device, token), and 3) Something you are (e.g., biometric) Non-privileged accounts are not authorized access to the network element regardless of access method. Network access is any access to an application by a user (or process acting on behalf of a user) where said access is obtained through a network connection. Authenticating with a PKI credential and entering the associated PIN is an example of multifactor authentication. This requirement applies to ALGs that provide user authentication intermediary services.
SRG-NET-000147
1 Rule
The ALG providing user authentication intermediary services must implement replay-resistant authentication mechanisms for network access to nonprivileged accounts.
Medium Severity
A replay attack may enable an unauthorized user to gain access to the application. Authentication sessions between the authenticator and the application validating the user credentials must not be vulnerable to a replay attack. An authentication process resists replay attacks if it is impractical to achieve a successful authentication by recording and replaying a previous authentication message. A nonprivileged account is any account with the authorizations of a nonprivileged user. Privileged roles are organization-defined roles assigned to individuals that allow those individuals to perform certain security-relevant functions that ordinary users are not authorized to perform. Security relevant roles include key management, account management, network and system administration, database administration, and web administration. Techniques used to address this include protocols using nonces (e.g., numbers generated for a specific one time use) or challenges (e.g., TLS). Additional techniques include time-synchronous or challenge-response one-time authenticators. This requirement applies to ALGs that provide user authentication intermediary services.
SRG-NET-000164
1 Rule
The ALG that provides intermediary services for TLS must validate certificates used for TLS functions by performing RFC 5280-compliant certification path validation.
Medium Severity
A certificate's certification path is the path from the end entity certificate to a trusted root certification authority (CA). Certification path validation is necessary for a relying party to make an informed decision regarding acceptance of an end entity certificate. Certification path validation includes checks such as certificate issuer trust, time validity and revocation status for each certificate in the certification path. Revocation status information for CA and subject certificates in a certification path is commonly provided via certificate revocation lists (CRLs) or online certificate status protocol (OCSP) responses.
SRG-NET-000166
1 Rule
The ALG providing PKI-based user authentication intermediary services must map authenticated identities to the user account.
Medium Severity
Authorization for access to any network element requires an approved and assigned individual account identifier. To ensure only the assigned individual is using the account, the account must be bound to a user certificate when PKI-based authentication is implemented. This requirement applies to ALGs that provide user authentication intermediary services (e.g., authentication gateway or TLS gateway). This does not apply to authentication for the purpose of configuring the device itself (device management).
SRG-NET-000169
1 Rule
The ALG providing user authentication intermediary services must uniquely identify and authenticate non-organizational users (or processes acting on behalf of non-organizational users).
Medium Severity
Lack of authentication enables anyone to gain access to the network or possibly a network element that provides opportunity for intruders to compromise resources within the network infrastructure. By identifying and authenticating non-organizational users, their access to network resources can be restricted accordingly. Non-organizational users will be uniquely identified and authenticated for all accesses other than those accesses explicitly identified and documented by the organization when related to the use of anonymous access. Authorization requires an individual account identifier that has been approved, assigned, and configured on an authentication server. Authentication of user identities is accomplished through the use of passwords, tokens, biometrics, or in the case of multifactor authentication, some combination thereof. This control applies to application layer gateways that provide content filtering and proxy services on network segments (e.g., DMZ) that allow access by non-organizational users. This requirement focuses on authentication requests to the proxied application for access to destination resources and policy filtering decisions rather than administrator and management functions.
SRG-NET-000192
1 Rule
The ALG providing content filtering must block outbound traffic containing known and unknown DoS attacks to protect against the use of internal information systems to launch any Denial of Service (DoS) attacks against other networks or endpoints.
Medium Severity
DoS attacks can take multiple forms but have the common objective of overloading or blocking a network or host to deny or seriously degrade performance. If the network does not provide safeguards against DoS attack, network resources will be unavailable to users. Installation of an ALG at key boundaries in the architecture mitigates the risk of DoS attacks. These attacks can be detected by matching observed communications traffic with patterns of known attacks and monitoring for anomalies in traffic volume/type. The ALG must include protection against DoS attacks that originate from inside the enclave which can affect either internal or external systems. These attacks may use legitimate or rogue endpoints from inside the enclave. These attacks can be simple "floods" of traffic to saturate circuits or devices, malware that consumes CPU and memory on a device or causes it to crash, or a configuration issue that disables or impairs the proper function of a device. For example, an accidental or deliberate misconfiguration of a routing table can misdirect traffic for multiple networks. To comply with this requirement, the ALG must monitor outbound traffic for indications of known and unknown DoS attacks. Audit log capacity management along with techniques which prevent the logging of redundant information during an attack also guard against DoS attacks.
SRG-NET-000202
1 Rule
The ALG must deny network communications traffic by default and allow network communications traffic by exception (i.e., deny all, permit by exception).
Medium Severity
A deny-all, permit-by-exception network communications traffic policy ensures that only those connections which are essential and approved are allowed. As a managed interface, the ALG must block all inbound and outbound network communications traffic to the application being managed and controlled unless a policy filter is installed to explicitly allow the traffic. The allow policy filters must comply with the site's security policy. A deny all, permit by exception network communications traffic policy ensures that only those connections which are essential and approved, are allowed. This requirement applies to both inbound and outbound network communications traffic. All inbound and outbound traffic for which the ALG is acting as an intermediary or proxy must be denied by default.
SRG-NET-000213
1 Rule
The ALG must terminate all network connections associated with a communications session at the end of the session, or as follows: for in-band management sessions (privileged sessions), the session must be terminated after 10 minutes of inactivity; and for user sessions (non-privileged session), the session must be terminated after 15 minutes of inactivity.
Medium Severity
Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle session will also free up resources committed by the managed network element. Terminating network connections associated with communications sessions includes, for example, de-allocating associated TCP/IP address/port pairs at the operating system level, and de-allocating networking assignments at the application level if multiple application sessions are using a single operating system level network connection. ALGs may provide session control functionality as part of content filtering, load balancing, or proxy services.
SRG-NET-000228
1 Rule
The ALG must detect, at a minimum, mobile code that is unsigned or exhibiting unusual behavior, has not undergone a risk assessment, or is prohibited for use based on a risk assessment.
Medium Severity
Mobile code is defined as software modules obtained from remote systems, transferred across a network, and then downloaded and executed on a local system without explicit installation or execution by the recipient. Examples of mobile code include JavaScript, VBScript, Java applets, ActiveX controls, Flash animations, Shockwave videos, and macros embedded within Microsoft Office documents. Mobile code can be exploited to attack a host. It can be sent as an email attachment or embedded in other file formats not traditionally associated with executable code. While the ALG cannot replace the network IDS or the anti-virus and host-based IDS (HIDS) protection installed on the network's endpoints, vendor or locally created sensor rules can be implemented, which provide preemptive defense against both known and zero-day vulnerabilities. Many of the protections may provide defenses before vulnerabilities are discovered and rules or blacklist updates are distributed by anti-virus or malicious code solution vendors. To monitor for and detect known prohibited mobile code or approved mobile code that violates permitted usage requirements, the ALG must implement policy filters, rules, signatures, and anomaly analysis.
SRG-NET-000230
1 Rule
The ALG must protect the authenticity of communications sessions.
Medium Severity
Authenticity protection provides protection against man-in-the-middle attacks/session hijacking and the insertion of false information into sessions. This requirement focuses on communications protection for the application session rather than for the network packet and establishes grounds for confidence at both ends of communications sessions in ongoing identities of other parties and in the validity of information transmitted. Depending on the required degree of confidentiality and integrity, web services/SOA will require the use of mutual authentication (two-way/bidirectional).
SRG-NET-000231
1 Rule
The ALG must invalidate session identifiers upon user logout or other session termination.
Medium Severity
Captured sessions can be reused in "replay" attacks. This requirement limits the ability of adversaries from capturing and continuing to employ previously valid session IDs. Session IDs are tokens generated by web applications to uniquely identify an application user's session. Unique session identifiers or IDs are the opposite of sequentially generated session IDs, which can be easily guessed by an attacker. Unique session IDs help to reduce predictability of said identifiers. When a user logs out, or when any other session termination event occurs, the network element must terminate the user session to minimize the potential for an attacker to hijack that particular user session. ALGs act as an intermediary for application; therefore, session control is part of the function provided. This requirement focuses on communications protection at the application session, versus network packet level.
SRG-NET-000233
1 Rule
The ALG must recognize only system-generated session identifiers.
Medium Severity
Network elements (depending on function) utilize sessions and session identifiers to control application behavior and user access. If an attacker can guess the session identifier, or can inject or manually insert session information, the valid user's application session can be compromised. Unique session IDs address man-in-the-middle attacks, including session hijacking or insertion of false information into a session. If the attacker is unable to identify or guess the session information related to pending application traffic, they will have more difficulty in hijacking the session or otherwise manipulating valid sessions. This requirement focuses on communications protection for the application session rather than for the network packet.
SRG-NET-000234
1 Rule
The ALG must generate unique session identifiers using a FIPS 140-2 approved random number generator.
Medium Severity
Sequentially generated session IDs can be easily guessed by an attacker. Employing the concept of randomness in the generation of unique session identifiers helps to protect against brute-force attacks to determine future session identifiers. This requirement is applicable to ALGs that create and use sessions and session identifiers to control user communications. If an attacker can guess the session identifier, or can inject or manually insert session information, the valid user's application session can be compromised.
SRG-NET-000235
1 Rule
The ALG must fail to a secure state upon failure of initialization, shutdown, or abort actions.
Medium Severity
Failure to a known safe state helps prevent systems from failing to a state that may cause loss of data or unauthorized access to system resources. Network elements that fail suddenly and with no incorporated failure state planning may leave the hosting system available but with a reduced security protection capability. Preserving information system state information also facilitates system restart and return to the operational mode of the organization with less disruption to mission-essential processes. An example is a firewall that blocks all traffic rather than allowing all traffic when a firewall component fails (e.g., fail closed and do not forward traffic). This prevents an attacker from forcing a failure of the system in order to obtain access. This applies to the configuration of the gateway or network traffic security function of the device. Abort refers to stopping a program or function before it has finished naturally. The term abort refers to both requested and unexpected terminations.
SRG-NET-000236
1 Rule
In the event of a system failure of the ALG function, the ALG must save diagnostic information, log system messages, and load the most current security policies, rules, and signatures when restarted.
Medium Severity
Failure in a secure state can address safety or security in accordance with the mission needs of the organization. Failure to a secure state helps prevent a loss of confidentiality, integrity, or availability in the event of a failure of the information system or a component of the system. Preserving state information helps to facilitate the restart of the ALG application and a return to the operational mode with less disruption. This requirement applies to a failure of the ALG function rather than the device or operating system as a whole which is addressed in the Network Device Management SRG. Since it is usually not possible to test this capability in a production environment, systems should either be validated in a testing environment or prior to installation. This requirement is usually a function of the design of the IDPS component. Compliance can be verified by acceptance/validation processes or vendor attestation.
SRG-NET-000246
1 Rule
The ALG providing content filtering must update malicious code protection mechanisms and signature definitions whenever new releases are available in accordance with organizational configuration management policy.
Medium Severity
Malicious code protection mechanisms include, but are not limited to, antivirus and malware detection software. To minimize any potential negative impact to the organization caused by malicious code, malicious code must be identified and eradicated. Malicious code includes viruses, worms, Trojan horses, and spyware. This requirement is limited to ALGs, web content filters, and packet inspection firewalls that perform malicious code detection as part of their functionality.
SRG-NET-000248
1 Rule
The ALG providing content filtering must be configured to perform real-time scans of files from external sources at network entry/exit points as they are downloaded and prior to being opened or executed.
Medium Severity
Malicious code includes viruses, worms, Trojan horses, and spyware. The code provides the ability for a malicious user to read from and write to files and folders on a computer's hard drive. Malicious code may also be able to run and attach programs, which may allow the unauthorized distribution of malicious mobile code. Once this code is installed on endpoints within the network, unauthorized users may be able to breach firewalls and gain access to sensitive data. To guard against malicious code, real-time scans must be performed on files from external sources as they are downloaded and prior to being opened or executed. This requirement is limited to ALGs, web content filters, and packet inspection firewalls that perform malicious code detection as part of their functionality.
SRG-NET-000249
1 Rule
The ALG providing content filtering must block malicious code upon detection.
Medium Severity
Taking an appropriate action based on local organizational incident handling procedures minimizes the impact of this code on the network. This requirement is limited to ALGs web content filters and packet inspection firewalls; that perform malicious code detection as part of their functionality.
SRG-NET-000249
1 Rule
The ALG providing content filtering must delete or quarantine malicious code in response to malicious code detection.
Medium Severity
Taking an appropriate action based on local organizational incident handling procedures minimizes the impact of this code on the network. The ALG must be configured to block all detected malicious code. It is sometimes acceptable/necessary to generate a log event and then automatically delete the malicious code; however for critical attacks or where forensic evidence is deemed necessary, the file should be quarantined for further investigation. This requirement is limited to ALGs web content filters and packet inspection firewalls; that perform malicious code detection as part of their functionality.
SRG-NET-000249
1 Rule
The ALG providing content filtering must send an immediate (within seconds) alert to the system administrator, at a minimum, in response to malicious code detection.
Medium Severity
Without an alert, security personnel may be unaware of an impending failure of the audit capability; then the ability to perform forensic analysis and detect rate-based and other anomalies will be impeded. The ALG generates an immediate (within seconds) alert which notifies designated personnel of the incident. Sending a message to an unattended log or console does not meet this requirement since that will not be seen immediately. These messages should include a severity level indicator or code as an indicator of the criticality of the incident.
SRG-NET-000251
1 Rule
The ALG providing content filtering must update malicious code protection mechanisms and signature definitions whenever new releases are available in accordance with organizational configuration management procedures.
Medium Severity
The malicious software detection functionality on network elements needs to be constantly updated in order to identify new threats as they are discovered. All malicious software detection functions must come with an update mechanism that automatically updates the application and any associated signature definitions. The organization (including any contractor to the organization) is required to promptly install security-relevant malicious code protection updates. Examples of relevant updates include anti-virus signatures, detection heuristic rule sets, and/or file reputation data employed to identify and/or block malicious software from executing. Malicious code includes viruses, worms, Trojan horses, and Spyware. This requirement is limited to ALGs, web content filters, and packet inspection firewalls that perform malicious code detection as part of their functionality.
SRG-NET-000273
1 Rule
The ALG must generate error messages that provide the information necessary for corrective actions without revealing information that could be exploited by adversaries.
Medium Severity
Providing too much information in error messages risks compromising the data and security of the application and system. Organizations carefully consider the structure/content of error messages. The required information within error messages will vary based on the protocol and error condition. Information that could be exploited by adversaries includes, for example, ICMP messages that reveal the use of firewalls or access-control lists.
SRG-NET-000280
1 Rule
The ALG that is part of a CDS must enforce information flow control based on organization-defined metadata.
Medium Severity
Enforcing allowed information flows based on metadata enables simpler and more effective flow control. Metadata is information used to describe the characteristics of data. Metadata can include structural metadata describing data structures (e.g., data format, syntax, and semantics) or descriptive metadata describing data contents (e.g., age, location, telephone number). Information flow control regulates where information is allowed to travel within a network and between hosts, as opposed to who is allowed to access the information. Information flow enforcement mechanisms, such as cross domain solutions, compare metadata attached to the data and respond appropriately (e.g., allow, block, quarantine, or alert administrator). Organization-defined metadata used for flow control in CDS systems depend on the environment, data, and security boundaries. Organizations implementing CDS must follow the DoD-required process of testing, baselining, and risk assessment to ensure the rigor and accuracy necessary to rely upon a CDS for cross domain security.
SRG-NET-000280
1 Rule
The ALG that is part of a CDS must block the transfer of data with malformed security attribute metadata structures.
Medium Severity
Enforcing allowed information flows based on metadata enables simpler and more effective flow control. Metadata is information used to describe the characteristics of data. Metadata can include structural metadata describing data structures (e.g., data format, syntax, and semantics) or descriptive metadata describing data contents (e.g., age, location, telephone number). For cross domain solutions, security attributes are defined as, at a minimum, source and destination address.
SRG-NET-000282
1 Rule
The ALG that is part of a CDS must decompose information into organization-defined, policy-relevant subcomponents for submission to policy enforcement mechanisms before transferring information between different security domains.
Medium Severity
Policy enforcement mechanisms apply filtering, inspection, and/or sanitization rules to the policy-relevant subcomponents of information to facilitate flow enforcement prior to transferring such information to different security domains. Parsing transfer files facilitates policy decisions on source, destination, certificates, classification, attachments, and other security-related component differentiators. Policy enforcement mechanisms include the filtering and/or sanitization rules applied to information before transferring to a different security domain. The organization-defined subcomponents for CDS systems depend on the environment, data, and security boundaries. Organizations implementing CDS must follow the DoD-required process of testing, baselining, and risk assessment to ensure the rigor and accuracy necessary to rely upon a CDS for cross domain security.
SRG-NET-000283
1 Rule
The ALG that is part of a CDS, when transferring information between different security domains, must implement organization-defined security policy filters requiring fully enumerated formats that restrict data structure and content.
Medium Severity
Data structure and content restrictions reduce the range of potential malicious and/or unsanctioned content in cross-domain transactions. Security policy filters that restrict data structures include, for example, restricting file sizes and field lengths. Data content policy filters include: 1) Encoding formats for character sets (e.g., Universal Character Set Transformation Formats) 2) American Standard Code for Information Interchange (ASCII) 3) Restricting character data fields to only contain alpha-numeric characters 4) Prohibiting special characters 5) Validating schema structures Organization-defined security policy filters which require format restrictions depend on the environment, data, and security boundaries. Organizations implementing CDS must follow the DoD-required process of testing, baselining, and risk assessment to ensure the rigor and accuracy necessary to rely upon a CDS for cross domain security.
SRG-NET-000284
1 Rule
The ALG that is part of a CDS, when transferring information between different security domains, must examine the information for the presence of organization-defined unsanctioned information.
Medium Severity
Without the capability to examine information, there is no means to determine the presence of information not authorized for transfer. Information flow decisions based on unexamined data may allow unintended and unauthorized data flows and therefore risk the confidentiality of information and may also result in the unauthorized release (spillage) of information. Detection of unsanctioned information includes, for example, checking all information to be transferred for malicious code and key words which may indicate an OPSEC violation. Organization-defined unsanctioned information depends on the environment, data, and security boundaries of the specific CDS. Organizations implementing CDS must follow the DoD-required process of testing, baselining, and risk assessment to ensure the rigor and accuracy necessary to rely upon a CDS for cross domain security.
SRG-NET-000285
1 Rule
The ALG that is part of a CDS must prohibit the transfer of unsanctioned information in accordance with the security policy when transferring information between different security domains.
Medium Severity
The ability to prohibit information transfer is fundamentally necessary to prevent unintended and unauthorized data flows. Failure to prohibit information transfer when necessary will risk the confidentiality of information and may also result in the unauthorized release (spillage) of information. Detection of unsanctioned information includes, for example, checking all information to be transferred for malicious code and key words which may indicate an OPSEC violation.
SRG-NET-000288
1 Rule
The ALG providing content filtering must block or restrict detected prohibited mobile code.
Medium Severity
Mobile code is defined as software modules obtained from remote systems, transferred across a network, and then downloaded and executed on a local system without explicit installation or execution by the recipient. This applies to mobile code that may originate either internal to or external from the enclave. Mobile code is defined as software modules obtained from remote systems, transferred across a network, and then downloaded and executed on a local system without explicit installation or execution by the recipient. Mobile code which must be blocked or restricted is identified in CCI-001166.
SRG-NET-000289
1 Rule
The ALG providing content filtering must prevent the download of prohibited mobile code.
Medium Severity
Mobile code is defined as software modules obtained from remote systems, transferred across a network, and then downloaded and executed on a local system without explicit installation or execution by the recipient. This applies to mobile code that may originate either internal to or external from the enclave. Mobile code is defined as software modules obtained from remote systems, transferred across a network, and then downloaded and executed on a local system without explicit installation or execution by the recipient. Mobile code which must be prevented from downloading is identified in CCI-001166.
SRG-NET-000313
1 Rule
The ALG providing intermediary services for remote access communications traffic must control remote access methods.
Medium Severity
Remote access devices, such as those providing remote access to network devices and information systems, which lack automated control capabilities, increase risk and makes remote user access management difficult at best. Remote access is access to DoD-nonpublic information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network. Remote access methods include broadband and wireless connections. Remote access methods include, for example, proxied remote encrypted traffic (e.g., TLS gateways, web content filters, and webmail proxies). This requirement applies to ALGs providing remote access proxy services as part of its intermediary services (e.g., OWA or TLS gateway). ALGs that proxy remote access must be capable of taking enforcement action (i.e., blocking, restricting, or forwarding to an enforcement mechanism) if traffic monitoring reveals unauthorized activity.
SRG-NET-000314
1 Rule
The ALG providing intermediary services for remote access communications traffic must provide the capability to immediately disconnect or disable remote access to the information system.
Medium Severity
Without the ability to immediately disconnect or disable remote access, an attack or other compromise taking progress would not be immediately stopped. Remote access functionality must have the capability to immediately disconnect current users remotely accessing the information system and/or disable further remote access. The remote access functionality may implement features, such as automatic disconnect (or user-initiated disconnect) in case of adverse information based on an indicator of compromise or attack. This requirement applies to ALGs providing remote access termination (e.g., OWA or TLS gateway) as part of its intermediary services.
SRG-NET-000318
1 Rule
To protect against data mining, the ALG providing content filtering must prevent code injection attacks from being launched against data storage objects, including, at a minimum, databases, database records, queries, and fields.
Medium Severity
Data mining is the analysis of large quantities of data to discover patterns and is used in intelligence gathering. Failure to prevent attacks launched against organizational information from unauthorized data mining may result in the compromise of information. Injection attacks allow an attacker to inject code into a program or query or inject malware onto a computer to execute remote commands that can read or modify a database, or change data on a website. Web applications frequently access databases to store, retrieve, and update information. An attacker can construct inputs that the database will execute. This is most commonly referred to as a code injection attack. This type of attack includes XPath and LDAP injections. Compliance requires the ALG to have the capability to prevent code injections. Examples include a Web Application Firewalls (WAFs) or database application gateways.
SRG-NET-000318
1 Rule
To protect against data mining, the ALG providing content filtering must prevent code injection attacks launched against application objects including, at a minimum, application URLs and application code.
Medium Severity
Data mining is the analysis of large quantities of data to discover patterns and is used in intelligence gathering. Failure to prevent attacks launched against organizational information from unauthorized data mining may result in the compromise of information. Injection attacks allow an attacker to inject code into a program or query or inject malware onto a computer to execute remote commands that can read or modify a database, or change data on a website. These attacks include buffer overrun, XML, JavaScript, and HTML injections. Compliance requires the ALG to have the capability to prevent code injections. Examples include a Web Application Firewalls (WAFs) or database application gateways.
SRG-NET-000318
1 Rule
To protect against data mining, the ALG providing content filtering must prevent SQL injection attacks launched against data storage objects, including, at a minimum, databases, database records, and database fields.
Medium Severity
Data mining is the analysis of large quantities of data to discover patterns and is used in intelligence gathering. Failure to prevent attacks launched against organizational information from unauthorized data mining may result in the compromise of information. SQL injection attacks are the most prevalent attacks against web applications and databases. These attacks inject SQL commands that can read, modify, or compromise the meaning of the original SQL query. An attacker can spoof identity; expose, tamper, destroy, or make existing data unavailable; or gain unauthorized privileges on the database server. Compliance requires the ALG to have the capability to prevent SQL code injections. Examples include a Web Application Firewalls (WAFs) or database application gateways.
SRG-NET-000319
1 Rule
To protect against data mining, the ALG providing content filtering must detect code injection attacks from being launched against data storage objects, including, at a minimum, databases, database records, queries, and fields.
Medium Severity
Data mining is the analysis of large quantities of data to discover patterns and is used in intelligence gathering. Failure to detect attacks launched against organizational databases may result in the compromise of information. Injection attacks allow an attacker to inject code into a program or query or inject malware onto a computer to execute remote commands that can read or modify a database, or change data on a website. Web applications frequently access databases to store, retrieve, and update information. An attacker can construct inputs that the database will execute. This is most commonly referred to as a code injection attack. This type of attack includes XPath and LDAP injections. ALGs with anomaly detection must be configured to protect against unauthorized code injections. These devices must include rules and anomaly detection algorithms to monitor for atypical database queries or accesses. Examples include a Web Application Firewalls (WAFs) or database application gateways.
SRG-NET-000319
1 Rule
To protect against data mining, the ALG providing content filtering must detect SQL injection attacks launched against data storage objects, including, at a minimum, databases, database records, and database fields.
Medium Severity
Data mining is the analysis of large quantities of data to discover patterns and is used in intelligence gathering. Failure to detect attacks launched against organizational databases may result in the compromise of information. SQL injection attacks are the most prevalent attacks against web applications and databases. These attacks inject SQL commands that can read, modify, or compromise the meaning of the original SQL query. An attacker can spoof identity; expose, tamper, destroy, or make existing data unavailable; or gain unauthorized privileges on the database server. ALGs with anomaly detection must be configured to protect against unauthorized data mining attacks. These devices must include rules and anomaly detection algorithms to monitor for atypical database queries or accesses. Examples include a Web Application Firewalls (WAFs) or database application gateways.
SRG-NET-000319
1 Rule
To protect against data mining, the ALG providing content filtering as part of its intermediary services must detect code injection attacks launched against application objects including, at a minimum, application URLs and application code.
Medium Severity
Data mining is the analysis of large quantities of data to discover patterns and is used in intelligence gathering. Failure to detect attacks launched against organizational applications may result in the compromise of information. Injection attacks allow an attacker to inject code into a program or query or inject malware onto a computer to execute remote commands that can read or modify a database, or change data on a website. These attacks include buffer overrun, XML, JavaScript, and HTML injections. ALGs with anomaly detection must be configured to protect against unauthorized code injections. These devices must include rules and anomaly detection algorithms to monitor for atypical database queries or accesses. Examples include a Web Application Firewalls (WAFs) or database application gateways.
SRG-NET-000323
1 Rule
The ALG that is part of a CDS must use source and destination security attributes associated with organization-defined information, source, and/or destination objects to enforce organization-defined information flow control policies as a basis for flow control decisions.
Medium Severity
If information flow is not enforced based on approved authorizations, the system may become compromised. A mechanism to detect and prevent unauthorized communication flow must be configured and used to filter information flow across security boundaries protected by the ALG. Information flow control regulates where information is allowed to travel within a system and between interconnected systems. Security attributes may be used to manage information flow control. Organization-defined information and organization-defined information flow control policies for CDS systems depend on the environment, data, and security boundaries. Organizations implementing CDS must follow the DoD-required process of testing, baselining, and risk assessment to ensure the rigor and accuracy necessary to rely upon a CDS for cross domain security. Information flow enforcement mechanisms compare security attributes associated with information (data content and data structure) and/or source/destination objects. The ALG uses the result of the attribute-object comparison to take an organization-defined action based on configured rules. Security attributes most often include source and destination addresses.
SRG-NET-000324
1 Rule
The ALG that is part of a CDS, when transferring information between different security domains, must use organization-defined data type identifiers to validate data essential for information flow decisions.
Medium Severity
Information flow decisions based on invalid data may allow unintended and unauthorized data flows, and therefore risk the confidentiality of information. They may also result in the unauthorized release (spill) of information. Data type identifiers include, for example, file names, file types, file signatures/tokens, and multiple internal file signatures/tokens. Information systems may allow transfer of data only if compliant with data type format specifications.
SRG-NET-000325
1 Rule
The ALG that is part of a CDS must uniquely identify and authenticate source by organization, system, application, and/or individual for information transfer.
Medium Severity
Attribution is a critical component of a security concept of operations. The ability to identify source and destination points for information flowing in information systems, allows the forensic reconstruction of events when required, and encourages policy compliance by attributing policy violations to specific organizations/individuals. Successful domain authentication requires that information system labels distinguish among systems, organizations, and individuals involved in preparing, sending, receiving, or disseminating information.
SRG-NET-000326
1 Rule
The ALG that is part of a CDS must uniquely identify and authenticate destination by organization, system, application, and/or individual for information transfer.
Medium Severity
Attribution is a critical component of a security concept of operations. The ability to identify source and destination points for information flowing in information systems, allows the forensic reconstruction of events when required, and encourages policy compliance by attributing policy violations to specific organizations/individuals. Successful domain authentication requires that information system labels distinguish among systems, organizations, and individuals involved in preparing, sending, receiving, or disseminating information.
SRG-NET-000328
1 Rule
The ALG that is part of a CDS, when transferring information between different security domains, must apply the same security policy filtering to metadata as it applies to data payloads.
Medium Severity
Subjecting metadata to the same filtering and inspection policies as payload data helps to mitigate the risk of data compromise through covert channels. This security measure also helps prevent the bypassing of security policy filtering.
SRG-NET-000329
1 Rule
The ALG that is part of a CDS must enforce the use of human reviews for organization-defined information flows under organization-defined conditions.
Medium Severity
Without network element enforcement of human reviews, security policy filters may have false positives and false negatives in marginal situations, which may result in loss of confidentiality or availability. Organizations define security policy filters for all situations where automated flow control decisions are possible. When a fully automated flow control decision is not possible, then a human review may be employed in lieu of, or as a complement to, automated security policy filtering. Human reviews may also be employed as deemed necessary by organizations. The cross domain solution will display the data which requires human review to the authorized reviewer in its native form (i.e., consistent with how it would be displayed by the application that created the data). The system will require a response from the authorized reviewer prior to taking action on the transfer data and then take appropriate actions as indicated by the reviewer (e.g., reject, forward, reply, etc.), but do not allow the reviewer to circumvent any additional filtering mechanisms. Organization-defined information flows and conditions used as part of a CDS system depend on the environment, data, and security boundaries. Organizations implementing CDS must follow the DoD-required process of testing, baselining, and risk assessment to ensure the rigor and accuracy necessary to rely upon a CDS for cross domain security.
SRG-NET-000331
1 Rule
The ALG providing user access control intermediary services must provide the capability for authorized users to select a user session to capture or view.
Medium Severity
Without the capability to select a user session to capture or view, investigations into suspicious or harmful events would be hampered by the volume of information captured. The intent of this requirement is to ensure the capability to select specific sessions to capture is available in order to support general auditing/incident investigation, or to validate suspected misuse by a specific user. Examples of session events that may be captured include, port mirroring, tracking websites visited, and recording information and/or file transfers.
SRG-NET-000334
1 Rule
The ALG must off-load audit records onto a centralized log server.
Medium Severity
Information stored in one location is vulnerable to accidental or incidental deletion or alteration. Off-loading is a common process in information systems with limited audit storage capacity. This does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000335
1 Rule
The ALG must provide an immediate real-time alert to, at a minimum, the SCA and ISSO, of all audit failure events where the detection and/or prevention function is unable to write events to either local storage or the centralized server.
Medium Severity
Without a real-time alert, security personnel may be unaware of an impending failure of the audit capability and system operation may be adversely affected. Alerts provide organizations with urgent messages. Real-time alerts provide these messages immediately (i.e., the time from event detection to alert occurs in seconds or less). This does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000337
1 Rule
The ALG providing user authentication intermediary services must require users to reauthenticate when organization-defined circumstances or situations require reauthentication.
Medium Severity
Without reauthentication, users may access resources or perform tasks for which they do not have authorization. In addition to the reauthentication requirements associated with session locks, organizations may require reauthentication of individuals and/or devices in other situations, including (but not limited to) the following circumstances: 1) When authenticators change. 2) When roles change. 3) When security categories of information systems change. 4) When the execution of privileged functions occurs. 5) After a fixed period of time. 6) Periodically. Within the DOD, the minimum circumstances requiring reauthentication are privilege escalation and role changes. This requirement only applies to components for which this is specific to the function of the device or has the concept of user authentication (e.g., VPN or ALG capability). This does not apply to authentication for the purpose of configuring the device itself (i.e., device management).
SRG-NET-000339
1 Rule
The ALG providing user authentication intermediary services must implement multifactor authentication for remote access to nonprivileged accounts such that one of the factors is provided by a device separate from the system gaining access.
Medium Severity
For remote access to nonprivileged accounts, the purpose of requiring a device that is separate from the information system gaining access for one of the factors during multifactor authentication is to reduce the likelihood of compromising authentication credentials stored on the system. Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-based or challenge-response authenticators and smart cards such as the U.S. Government Personal Identity Verification (PIV) card and the DOD common access card (CAC). A privileged account is defined as an information system account with authorizations of a privileged user. Remote access is access to DOD-nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. An example of compliance with this requirement is the use of a one-time password token and PIN coupled with a password; or the use of a CAC/PIV card and PIN coupled with a password.
SRG-NET-000340
1 Rule
The ALG providing user authentication intermediary services must implement multifactor authentication for remote access to privileged accounts such that one of the factors is provided by a device separate from the system gaining access.
Medium Severity
For remote access to privileged accounts, the purpose of requiring a device that is separate from the information system gaining access for one of the factors during multifactor authentication is to reduce the likelihood of compromising authentication credentials stored on the system. Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-based or challenge-response authenticators and smart cards such as the U.S. Government Personal Identity Verification (PIV) card and the DOD common access card (CAC). A privileged account is defined as an information system account with authorizations of a privileged user. Remote access is access to DOD-nonpublic information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless.
SRG-NET-000344
1 Rule
The ALG must prohibit the use of cached authenticators after an organization-defined time period.
Medium Severity
If the cached authenticator information is out of date, the validity of the authentication information may be questionable. This requirement applies to all ALGs which may cache user authenticators for use throughout a session. This requirement also applies to ALGs that provide user authentication intermediary services (e.g., authentication gateway or TLS gateway). This does not apply to authentication for the purpose of configuring the device itself (device management).
SRG-NET-000345
1 Rule
The ALG providing user authentication intermediary services using PKI-based user authentication must implement a local cache of revocation data to support path discovery and validation in case of the inability to access revocation information via the network.
Medium Severity
Without configuring a local cache of revocation data, there is the potential to allow access to users who are no longer authorized (users with revoked certificates). The intent of this requirement is to require support for a secondary certificate validation method using a locally cached revocation data, such as Certificate Revocation List (CRL), in case access to OCSP (required by CCI-000185) is not available. Based on a risk assessment, an alternate mitigation is to configure the system to deny access when revocation data is unavailable. This requirement applies to ALGs that provide user authentication intermediary services (e.g., authentication gateway or TLS gateway). This does not apply to authentication for the purpose of configuring the device itself (device management).
SRG-NET-000349
1 Rule
The ALG providing user authentication intermediary services must conform to Federal Identity, Credential, and Access Management (FICAM)-issued profiles.
Medium Severity
Without conforming to FICAM-issued profiles, the information system may not be interoperable with FICAM-authentication protocols, such as SAML 2.0 and OpenID 2.0. Use of FICAM-issued profiles addresses open identity management standards. This requirement only applies to components where this is specific to the function of the device or has the concept of a nonorganizational user, (e.g., ALG capability that is the front end for an application in a DMZ).
SRG-NET-000355
1 Rule
The ALG providing user authentication intermediary services using PKI-based user authentication must only accept end entity certificates issued by DoD PKI or DoD-approved PKI Certification Authorities (CAs) for the establishment of protected sessions.
Medium Severity
Non-DoD approved PKIs have not been evaluated to ensure that they have security controls and identity vetting procedures in place which are sufficient for DoD systems to rely on the identity asserted in the certificate. PKIs lacking sufficient security controls and identity vetting procedures risk being compromised and issuing certificates that enable adversaries to impersonate legitimate users. The authoritative list of DoD-approved PKIs is published at http://iase.disa.mil/pki-pke/interoperability. DoD-approved PKI CAs may include Category I, II, and III certificates. Category I DoD-Approved External PKIs are PIV issuers. Category II DoD-Approved External PKIs are Non-Federal Agency PKIs cross certified with the Federal Bridge Certification Authority (FBCA). Category III DoD-Approved External PKIs are Foreign, Allied, or Coalition Partner PKIs. Deploying the ALG with TLS enabled will require the installation of DoD and/or DoD-Approved CA certificates in the trusted root certificate store of each proxy to be used for TLS traffic. This requirement focuses on communications protection for the application session rather than for the network packet.
SRG-NET-000362
1 Rule
The ALG providing content filtering must protect against known and unknown types of Denial of Service (DoS) attacks by employing rate-based attack prevention behavior analysis.
Medium Severity
If the network does not provide safeguards against DoS attacks, network resources will be unavailable to users. Installation of content filtering gateways and application layer firewalls at key boundaries in the architecture mitigates the risk of DoS attacks. These attacks can be detected by matching observed communications traffic with patterns of known attacks and monitoring for anomalies in traffic volume/type. Detection components that use rate-based behavior analysis can detect attacks when signatures for the attack do not exist or are not installed. These attacks include zero-day attacks which are new attacks for which vendors have not yet developed signatures. Rate-based behavior analysis can detect sophisticated, Distributed DoS (DDoS) attacks by correlating traffic information from multiple network segments or components. This requirement applies to the communications traffic functionality of the ALG as it pertains to handling communications traffic, rather than to the ALG device itself.
SRG-NET-000362
1 Rule
The ALG must implement load balancing to limit the effects of known and unknown types of Denial of Service (DoS) attacks.
Medium Severity
If the network does not provide safeguards against DoS attacks, network resources will be unavailable to users. Load balancing provides service redundancy; which service redundancy reduces the susceptibility of the ALG to many DoS attacks. The ALG must be configured to prevent or mitigate the impact on network availability and traffic flow of DoS attacks that have occurred or are ongoing. This requirement applies to the network traffic functionality of the device as it pertains to handling network traffic. Some types of attacks may be specialized to certain network technologies, functions, or services. For each technology, known and potential DoS attacks must be identified and solutions for each type implemented.
SRG-NET-000362
1 Rule
The ALG providing content filtering must protect against known types of Denial of Service (DoS) attacks by employing signatures.
Medium Severity
If the network does not provide safeguards against DoS attacks, network resources will be unavailable to users. Installation of content filtering gateways and application layer firewalls at key boundaries in the architecture mitigates the risk of DoS attacks. These attacks can be detected by matching observed communications traffic with patterns of known attacks and monitoring for anomalies in traffic volume, type, or protocol usage. Detection components that use signatures can detect known attacks by using known attack signatures. Signatures are usually obtained from and updated by the ALG component vendor. This requirement applies to the communications traffic functionality of the ALG as it pertains to handling communications traffic, rather than to the ALG device itself.
SRG-NET-000362
1 Rule
The ALG providing content filtering must protect against or limit the effects of known and unknown types of Denial of Service (DoS) attacks by employing pattern recognition pre-processors.
Medium Severity
If the network does not provide safeguards against DoS attacks, network resources will be unavailable to users. Installation of content filtering gateways and application layer firewalls at key boundaries in the architecture mitigates the risk of DoS attacks. These attacks can be detected by matching observed communications traffic with patterns of known attacks. Detection components that use pattern recognition pre-processors can detect attacks when signatures for the attack do not exist or are not installed. These attacks include zero-day attacks which are new attacks for which vendors have not yet developed signatures. This requirement applies to the communications traffic functionality of the ALG as it pertains to handling communications traffic, rather than to the ALG device itself.
SRG-NET-000364
1 Rule
The ALG must only allow incoming communications from organization-defined authorized sources routed to organization-defined authorized destinations.
Medium Severity
Unrestricted traffic may contain malicious traffic which poses a threat to an enclave or to other connected networks. Additionally, unrestricted traffic may transit a network, which uses bandwidth and other resources. Access control policies and access control lists implemented on devices that control the flow of network traffic (e.g., application level firewalls and Web content filters), ensure the flow of traffic is only allowed from authorized sources to authorized destinations. Networks with different levels of trust (e.g., the Internet or CDS) must be kept separate.
SRG-NET-000365
1 Rule
The ALG must fail securely in the event of an operational failure.
Medium Severity
If a boundary protection device fails in an unsecure manner (open), information external to the boundary protection device may enter, or the device may permit unauthorized information release. Secure failure ensures when a boundary control device fails, all traffic will be subsequently denied. Fail secure is a condition achieved by employing information system mechanisms to ensure in the event of operational failures of boundary protection devices at managed interfaces (e.g., routers, firewalls, guards, and application gateways residing on protected subnetworks commonly referred to as demilitarized zones), information systems do not enter into unsecure states where intended security properties no longer hold.
SRG-NET-000370
1 Rule
The ALG must identify and log internal users associated with denied outgoing communications traffic posing a threat to external information systems.
Medium Severity
Without identifying the users who initiated the traffic, it would be difficult to identify those responsible for the denied communications. This requirement applies to those network elements that perform Data Leakage Prevention (DLP) (e.g., ALGs, proxies, or application level firewalls).
SRG-NET-000380
1 Rule
The ALG must behave in a predictable and documented manner that reflects organizational and system objectives when invalid inputs are received.
Medium Severity
A common vulnerability of network elements is unpredictable behavior when invalid inputs are received. This requirement guards against adverse or unintended system behavior caused by invalid inputs, where information system responses to the invalid input may be disruptive or cause the system to fail into an unsafe state. The behavior will be derived from the organizational and system requirements and includes, but is not limited to, notification of the appropriate personnel, creating an audit record, and rejecting invalid input. This requirement applies to gateways and firewalls that perform content inspection or have higher-layer proxy functions.
SRG-NET-000383
1 Rule
The ALG providing content filtering must be configured to integrate with a system-wide intrusion detection system.
Medium Severity
Without coordinated reporting between separate devices, it is not possible to identify the true scale and possible target of an attack. Integration of the ALG with a system-wide intrusion detection system supports continuous monitoring and incident response programs. This requirement applies to monitoring at internal boundaries using TLS gateways, web content filters, email gateways, and other types of ALGs. ALGs can work as part of the network monitoring capabilities to off-load inspection functions from the external boundary IDPS by performing more granular content inspection of protocols at the upper layers of the OSI reference model.
SRG-NET-000384
1 Rule
The ALG providing content filtering must detect use of network services that have not been authorized or approved by the ISSM and ISSO, at a minimum.
Medium Severity
Unauthorized or unapproved network services lack organizational verification or validation and therefore may be unreliable or serve as malicious rogues for valid services. Examples of network services include service-oriented architectures (SOAs), cloud-based services (e.g., infrastructure as a service, platform as a service, or software as a service), cross-domain, Voice Over Internet Protocol, Instant Messaging, auto-execute, and file sharing. To comply with this requirement, the ALG may be configured to detect services either directly or indirectly (i.e., by detecting traffic associated with a service). This requirement applies to gateways/firewalls that perform content inspection or have higher-layer proxy functionality.
SRG-NET-000385
1 Rule
The ALG providing content filtering must generate a log record when unauthorized network services are detected.
Medium Severity
Unauthorized or unapproved network services lack organizational verification or validation and therefore may be unreliable or serve as malicious rogues for valid services. Examples of network services include service-oriented architectures (SOAs), cloud-based services (e.g., infrastructure as a service, platform as a service, or software as a service), cross-domain, Voice Over Internet Protocol, Instant Messaging, auto-execute, and file sharing.
SRG-NET-000385
1 Rule
The ALG providing content filtering must generate an alert to, at a minimum, the ISSO and ISSM when unauthorized network services are detected.
Medium Severity
Unauthorized or unapproved network services lack organizational verification or validation and therefore, may be unreliable or serve as malicious rogues for valid services. Automated mechanisms can be used to send automatic alerts or notifications. Such automatic alerts or notifications can be conveyed in a variety of ways (e.g., telephonically, via electronic mail, via text message, or via websites). The ALG must either send the alert to a management console that is actively monitored by authorized personnel or use a messaging capability to send the alert directly to designated personnel.
SRG-NET-000390
1 Rule
The ALG providing content filtering must continuously monitor inbound communications traffic crossing internal security boundaries for unusual or unauthorized activities or conditions.
Medium Severity
If inbound communications traffic is not continuously monitored, hostile activity may not be detected and prevented. Output from application and traffic monitoring serves as input to continuous monitoring and incident response programs. Internal monitoring includes the observation of events occurring on the network crosses internal boundaries at managed interfaces such as web content filters. Depending on the type of ALG, organizations can monitor information systems by monitoring audit activities, application access patterns, characteristics of access, content filtering, or unauthorized exporting of information across boundaries. Unusual/unauthorized activities or conditions may include large file transfers, long-time persistent connections, unusual protocols and ports in use, and attempted communications with suspected malicious external addresses.
SRG-NET-000391
1 Rule
The ALG providing content filtering must continuously monitor outbound communications traffic crossing internal security boundaries for unusual/unauthorized activities or conditions.
Medium Severity
If outbound communications traffic is not continuously monitored, hostile activity may not be detected and prevented. Output from application and traffic monitoring serves as input to continuous monitoring and incident response programs. Internal monitoring includes the observation of events occurring on the network crosses internal boundaries at managed interfaces such as web content filters. Depending on the type of ALG, organizations can monitor information systems by monitoring audit activities, application access patterns, characteristics of access, content filtering, or unauthorized exporting of information across boundaries. Unusual/unauthorized activities or conditions may include large file transfers, long-time persistent connections, unusual protocols and ports in use, and attempted communications with suspected malicious external addresses.
SRG-NET-000392
1 Rule
The ALG providing content filtering must send an alert to, at a minimum, the ISSO and ISSM when detection events occur.
Medium Severity
Without an alert, security personnel may be unaware of major detection incidents that require immediate action and this delay may result in the loss or compromise of information. Since these incidents require immediate action, these messages are assigned a critical or level 1 priority/severity, depending on the system's priority schema. In accordance with CCI-001242, the ALG which provides content inspection services are a real-time intrusion detection system. These systems must generate an alert when detection events from real-time monitoring occur. Alerts may be transmitted, for example, telephonically, by electronic mail messages, or by text messaging. The ALG must either send the alert to a management console that is actively monitored by authorized personnel or use a messaging capability to send the alert directly to designated personnel.
SRG-NET-000392
1 Rule
The ALG providing content filtering must generate an alert to, at a minimum, the ISSO and ISSM when threats identified by authoritative sources (e.g., IAVMs or CTOs) are detected.
Medium Severity
Without an alert, security personnel may be unaware of major detection incidents that require immediate action and this delay may result in the loss or compromise of information. The ALG generates an alert which notifies designated personnel of the Indicators of Compromise (IOCs) which require real-time alerts. These messages should include a severity level indicator or code as an indicator of the criticality of the incident. These indicators reflect the occurrence of a compromise or a potential compromise. Since these incidents require immediate action, these messages are assigned a critical or level 1 priority/severity, depending on the system's priority schema. Alerts may be transmitted, for example, telephonically, by electronic mail messages, or by text messaging. The ALG must either send the alert to a management console that is actively monitored by authorized personnel or use a messaging capability to send the alert directly to designated personnel.
SRG-NET-000392
1 Rule
The ALG providing content filtering must generate an alert to, at a minimum, the ISSO and ISSM when root level intrusion events which provide unauthorized privileged access are detected.
Medium Severity
Without an alert, security personnel may be unaware of major detection incidents that require immediate action and this delay may result in the loss or compromise of information. The ALG generates an alert which notifies designated personnel of the Indicators of Compromise (IOCs) which require real-time alerts. These messages should include a severity level indicator or code as an indicator of the criticality of the incident. These indicators reflect the occurrence of a compromise or a potential compromise. Since these incidents require immediate action, these messages are assigned a critical or level 1 priority/severity, depending on the system's priority schema. CJCSM 6510.01B, "Cyber Incident Handling Program", lists nine Cyber Incident and Reportable Event Categories. DoD has determined that categories identified by CJCSM 6510.01B Major Indicators (category 1, 2, 4, or 7 detection events) will require an alert when an event is detected. Alerts may be transmitted, for example, telephonically, by electronic mail messages, or by text messaging. The ALG must either send the alert to a management console that is actively monitored by authorized personnel or use a messaging capability to send the alert directly to designated personnel.
SRG-NET-000392
1 Rule
The ALG providing content filtering must generate an alert to, at a minimum, the ISSO and ISSM when user level intrusions which provide non-privileged access are detected.
Medium Severity
Without an alert, security personnel may be unaware of major detection incidents that require immediate action and this delay may result in the loss or compromise of information. The ALG generates an alert which notifies designated personnel of the Indicators of Compromise (IOCs) which require real-time alerts. These messages should include a severity level indicator or code as an indicator of the criticality of the incident. These indicators reflect the occurrence of a compromise or a potential compromise. Since these incidents require immediate action, these messages are assigned a critical or level 1 priority/severity, depending on the system's priority schema. CJCSM 6510.01B, "Cyber Incident Handling Program", lists nine Cyber Incident and Reportable Event Categories. DoD has determined that categories identified by CJCSM 6510.01B Major Indicators (category 1, 2, 4, or 7 detection events) will require an alert when an event is detected. Alerts may be transmitted, for example, telephonically, by electronic mail messages, or by text messaging. The ALG must either send the alert to a management console that is actively monitored by authorized personnel or use a messaging capability to send the alert directly to designated personnel.
SRG-NET-000392
1 Rule
The ALG providing content filtering must generate an alert to, at a minimum, the ISSO and ISSM when denial of service incidents are detected.
Medium Severity
Without an alert, security personnel may be unaware of major detection incidents that require immediate action and this delay may result in the loss or compromise of information. The ALG generates an alert which notifies designated personnel of the Indicators of Compromise (IOCs) which require real-time alerts. These messages should include a severity level indicator or code as an indicator of the criticality of the incident. These indicators reflect the occurrence of a compromise or a potential compromise. Since these incidents require immediate action, these messages are assigned a critical or level 1 priority/severity, depending on the system's priority schema. CJCSM 6510.01B, "Cyber Incident Handling Program", lists nine Cyber Incident and Reportable Event Categories. DoD has determined that categories identified by CJCSM 6510.01B Major Indicators (category 1, 2, 4, or 7 detection events) will require an alert when an event is detected. Alerts may be transmitted, for example, telephonically, by electronic mail messages, or by text messaging. The ALG must either send the alert to a management console that is actively monitored by authorized personnel or use a messaging capability to send the alert directly to designated personnel.
SRG-NET-000392
1 Rule
The ALG providing content filtering must generate an alert to, at a minimum, the ISSO and ISSM when new active propagation of malware infecting DoD systems or malicious code adversely affecting the operations and/or security of DoD systems is detected.
Medium Severity
Without an alert, security personnel may be unaware of major detection incidents that require immediate action and this delay may result in the loss or compromise of information. The ALG generates an alert which notifies designated personnel of the Indicators of Compromise (IOCs) which require real-time alerts. These messages should include a severity level indicator or code as an indicator of the criticality of the incident. These indicators reflect the occurrence of a compromise or a potential compromise. Since these incidents require immediate action, these messages are assigned a critical or level 1 priority/severity, depending on the system's priority schema. CJCSM 6510.01B, "Cyber Incident Handling Program", lists nine Cyber Incident and Reportable Event Categories. DoD has determined that categories identified by CJCSM 6510.01B Major Indicators (category 1, 2, 4, or 7 detection events) will require an alert when an event is detected. Alerts may be transmitted, for example, telephonically, by electronic mail messages, or by text messaging. The ALG must either send the alert to a management console that is actively monitored by authorized personnel or use a messaging capability to send the alert directly to designated personnel.
SRG-NET-000393
1 Rule
The ALG that implements spam protection mechanisms must be updated automatically.
Medium Severity
Originators of spam messages are constantly changing their techniques in order to defeat spam countermeasures; therefore, spam software must be constantly updated to address the changing threat. A manual update procedure is labor intensive and does not scale well in an enterprise environment. This risk may be mitigated by using an automatic update capability. Spam protection mechanisms include, for example, signature definitions, rule sets, and algorithms. This requirement applies to gateways and firewalls that perform content inspection or have higher-layer proxy functionality.
SRG-NET-000400
1 Rule
The ALG providing user authentication intermediary services must transmit only encrypted representations of passwords.
Medium Severity
Passwords need to be protected at all times and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised. This requirement applies to ALGs that provide user authentication intermediary services. This does not apply to authentication for the purpose of configuring the device itself (device management).
SRG-NET-000401
1 Rule
The ALG must check the validity of all data inputs except those specifically identified by the organization.
Medium Severity
Invalid user input occurs when a user inserts data or characters into an application's data entry fields and the application is unprepared to process that data. This results in unanticipated application behavior potentially leading to an application or information system compromise. Invalid input is one of the primary methods employed when attempting to compromise an application. Network devices with the functionality to perform application layer inspection may be leveraged to validate data content of network communications. Checking the valid syntax and semantics of information system inputs (e.g., character set, length, numerical range, and acceptable values) verifies that inputs match specified definitions for format and content. Software typically follows well-defined protocols that use structured messages (i.e., commands or queries) to communicate between software modules or system components. Structured messages can contain raw or unstructured data interspersed with metadata or control information. If network elements use attacker-supplied inputs to construct structured messages without properly encoding such messages, then the attacker could insert malicious commands or special characters that can cause the data to be interpreted as control information or metadata. Consequently, the module or component that receives the tainted output will perform the wrong operations or otherwise interpret the data incorrectly. Pre-screening inputs prior to passing to interpreters prevents the content from being unintentionally interpreted as commands. Input validation helps to ensure accurate and correct inputs and prevent attacks such as cross-site scripting and a variety of injection attacks. This requirement applies to gateways and firewalls that perform content inspection or have higher-layer proxy functionality.
SRG-NET-000402
1 Rule
The ALG must reveal error messages only to the ISSO, ISSM, and SCA.
Medium Severity
Only authorized personnel should be aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can give configuration details about the network element. Limiting access to system logs and administrative consoles to authorized personnel will help to mitigate this risk. However, user feedback and error messages should also be restricted by type and content in accordance with security best practices (e.g., ICMP messages).
SRG-NET-000492
1 Rule
The ALG must generate audit records when successful/unsuccessful attempts to access security objects occur.
Medium Severity
Without generating audit records that log usage of objects by subjects and other objects, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). Security objects are data objects which are controlled by security policy and bound to security attributes. This requirement applies to the ALG traffic management functions. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000493
1 Rule
The ALG that is part of a CDS must generate audit records when successful/unsuccessful attempts to access security levels occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). Access for different security levels maintains separation between resources (particularly stored data) of different security domains. This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000494
1 Rule
The ALG must generate audit records when successful/unsuccessful attempts to access categories of information (e.g., classification levels) occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000495
1 Rule
The ALG providing user access control intermediary services must generate audit records when successful/unsuccessful attempts to modify privileges occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000496
1 Rule
The ALG must generate audit records when successful/unsuccessful attempts to modify security objects occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). Security objects are data objects which are controlled by security policy and bound to security attributes. This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000497
1 Rule
The ALG must generate audit records when successful/unsuccessful attempts to modify security levels occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). Access for different security levels maintains separation between resources (particularly stored data) of different security domains. This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000498
1 Rule
The ALG must generate audit records when successful/unsuccessful attempts to modify categories of information (e.g., classification levels) occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000499
1 Rule
The ALG providing user access control intermediary services must generate audit records when successful/unsuccessful attempts to delete privileges occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000500
1 Rule
The ALG must generate audit records when successful/unsuccessful attempts to delete security levels occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). Access for different security levels maintains separation between resources (particularly stored data) of different security domains. This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000501
1 Rule
The ALG must generate audit records when successful/unsuccessful attempts to delete security objects occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). Security objects are data objects which are controlled by security policy and bound to security attributes. This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000502
1 Rule
The ALG must generate audit records when successful/unsuccessful attempts to delete categories of information (e.g., classification levels) occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000503
1 Rule
The ALG providing user access control intermediary services must generate audit records when successful/unsuccessful logon attempts occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000505
1 Rule
The ALG providing user access control intermediary services must generate audit records showing starting and ending time for user access to the system.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000510
1 Rule
The ALG providing encryption intermediary services must implement NIST FIPS-validated cryptography to generate cryptographic hashes.
Medium Severity
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The network element must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. This requirement applies only to ALGs that provide encryption intermediary services (e.g., HTTPS, TLS, or DNSSEC).
SRG-NET-000510
1 Rule
The ALG providing encryption intermediary services must implement NIST FIPS-validated cryptography for digital signatures.
Medium Severity
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The network element must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. This requirement applies only to ALGs that provide encryption intermediary services (e.g., HTTPS, TLS, or DNSSEC).
SRG-NET-000510
1 Rule
The ALG providing encryption intermediary services must use NIST FIPS-validated cryptography to implement encryption services.
Medium Severity
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The network element must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. This requirement applies only to ALGs that provide encryption intermediary services (e.g., HTTPS, TLS, or DNSSEC).
SRG-NET-000511
1 Rule
The ALG must off-load audit records onto a centralized log server in real time.
Medium Severity
Off-loading ensures audit information does not get overwritten if the limited audit storage capacity is reached and also protects the audit record in case the system/component being audited is compromised. Off-loading is a common process in information systems with limited audit storage capacity. The audit storage on the ALG is used only in a transitory fashion until the system can communicate with the centralized log server designated for storing the audit records, at which point the information is transferred. However, DoD requires that the log be transferred in real time which indicates that the time from event detection to off-loading is seconds or less. This does not apply to audit logs generated on behalf of the device itself (management).
SRG-NET-000511
1 Rule
The ALG that is part of a CDS must have the capability to implement journaling.
Medium Severity
A journaling file system is a file system that keeps track of the changes that will be made in a journal (usually a circular log in a dedicated area of the file system) before committing them to the main file system. In the event of a system crash or power failure, such file systems are quicker to bring back online and less likely to become corrupted. The internal format of the journal must guard against crashes while the journal itself is being written to. Many journal implementations (such as the JBD2 layer in ext4) bracket every change logged with a checksum, on the understanding that a crash would leave a partially written change with a missing (or mismatched) checksum that can simply be ignored when replaying the journal at next remount.
SRG-NET-000512
1 Rule
The ALG must be configured in accordance with the security configuration settings based on DoD security policy and technology-specific security best practices.
Medium Severity
Configuring the network element to implement organization-wide security implementation guides and security checklists ensures compliance with federal standards and establishes a common security baseline across DoD that reflects the most restrictive security posture consistent with operational requirements. Configuration settings are the set of parameters that can be changed that affect the security posture and/or functionality of the network element. Security-related parameters are those parameters impacting the security state of the network element, including the parameters required to satisfy other security control requirements. For the network element, security-related parameters include settings for network traffic management configurations.
SRG-NET-000512
1 Rule
The ALG that provides intermediary services for SMTP must inspect inbound and outbound SMTP and Extended SMTP communications traffic for protocol compliance and protocol anomalies.
Medium Severity
Application protocol anomaly detection examines application layer protocols such as SMTP to identify attacks based on observed deviations in the normal RFC behavior of a protocol or service. This type of monitoring allows for the detection of known and unknown exploits which exploit weaknesses of commonly used protocols. Since protocol anomaly analysis examines the application payload for patterns or anomalies, an SMTP proxy must be included in the ALG. This ALG will be configured to inspect inbound and outbound SMTP and Extended SMTP communications traffic to detect protocol anomalies such as malformed message and command insertion attacks.
SRG-NET-000512
1 Rule
The ALG that intermediary services for FTP must inspect inbound and outbound FTP communications traffic for protocol compliance and protocol anomalies.
Medium Severity
Application protocol anomaly detection examines application layer protocols such as FTP to identify attacks based on observed deviations in the normal RFC behavior of a protocol or service. This type of monitoring allows for the detection of known and unknown exploits which exploit weaknesses of commonly used protocols. Since protocol anomaly analysis examines the application payload for patterns or anomalies, an FTP proxy must be included in the ALG. This ALG will be configured to inspect inbound and outbound FTP communications traffic to detect protocol anomalies such as malformed message and command insertion attacks.
SRG-NET-000512
1 Rule
The ALG that provides intermediary services for HTTP must inspect inbound and outbound HTTP traffic for protocol compliance and protocol anomalies.
Medium Severity
Application protocol anomaly detection examines application layer protocols such as HTTP to identify attacks based on observed deviations in the normal RFC behavior of a protocol or service. This type of monitoring allows for the detection of known and unknown exploits which exploit weaknesses of commonly used protocols. Since protocol anomaly analysis examines the application payload for patterns or anomalies, an HTTP proxy must be included in the ALG. This ALG will be configured to inspect inbound and outbound HTTP communications traffic to detect protocol anomalies such as malformed message and command insertion attacks. All inbound and outbound traffic, including HTTPS, must be inspected. However, the intention of this policy is not to mandate HTTPS inspection by the ALG. Typically, HTTPS traffic is inspected either at the source, destination and/or is directed for inspection by organizationally-defined network termination point.
SRG-NET-000513
1 Rule
The ALG providing user access control intermediary services must generate audit records when successful/unsuccessful attempts to access privileges occur.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident, or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). Security objects are data objects which are controlled by security policy and bound to security attributes. This requirement applies to the ALG traffic management functions such as content filtering or intermediary services. This does not apply to audit logs generated on behalf of the device (device management).
SRG-NET-000514
1 Rule
The ALG providing user access control intermediary services must initiate a session lock after a 15-minute period of inactivity.
Medium Severity
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system, but does not log out because of the temporary nature of the absence. Rather than relying on the user to manually lock their session prior to vacating the vicinity, network elements need to be able to identify when a user's session has idled and take action to initiate the session lock. The session lock is implemented at the point where session activity can be determined and/or controlled. This policy only applies to gateways (e.g., identity management or authentication gateways) that provide user account services as part of the intermediary services.
SRG-NET-000515
1 Rule
The ALG providing user access control intermediary services must provide the capability for users to directly initiate a session lock.
Medium Severity
A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system, but does not want to log out because of the temporary nature of the absence. The session lock is implemented at the point where session activity can be determined. Rather than be forced to wait for a period of time to expire before the user session can be locked, network elements need to provide users with the ability to manually invoke a session lock so users may secure their session should the need arise for them to temporarily vacate the immediate physical vicinity. This policy only applies to gateways (e.g., identity management or authentication gateways) that provide user account services as part of the intermediary services.
SRG-NET-000516
1 Rule
The ALG providing user access control intermediary services must retain the session lock until the user reestablishes access using established identification and authentication procedures.
Medium Severity
A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system, but does not want to log out because of the temporary nature of the absence. The session lock is implemented at the point where session activity can be determined. Regardless of where the session lock is determined and implemented, once invoked the session lock shall remain in place until the user re-authenticates. No other activity aside from re-authentication shall unlock the system. This policy only applies to gateways (e.g., identity management or authentication gateways) that provide user account services as part of the intermediary services.
SRG-NET-000517
1 Rule
The ALG providing user access control intermediary services must automatically terminate a user session when organization-defined conditions or trigger events that require a session disconnect occur.
Medium Severity
Automatic session termination addresses the termination of user-initiated logical sessions in contrast to the termination of network connections that are associated with communications sessions (i.e., network disconnect). A logical session (for local, network, and remote access) is initiated whenever a user (or process acting on behalf of a user) accesses an organizational information system. Such user sessions can be terminated (and thus terminate user access) without terminating network sessions. Session termination terminates all processes associated with a user's logical session except those processes that are specifically created by the user (i.e., session owner) to continue after the session is terminated. This capability is typically reserved for specific system functionality where the system owner, data owner, or organization requires additional trigger events based on specific mission needs. Conditions or trigger events requiring automatic session termination can include, for example, targeted responses to certain types of incidents and time-of-day restrictions on information system use. This policy only applies to gateways (e.g., identity management or authentication gateways) that provide user account services as part of the intermediary services.
SRG-NET-000518
1 Rule
The ALG providing user access control intermediary services must provide a logoff capability for user-initiated communications sessions.
Medium Severity
If a user cannot explicitly end a session, the session may remain open and be exploited by an attacker. However, for some types of interactive sessions including, for example, remote logon, information systems typically send logoff messages as final messages prior to terminating sessions. This policy only applies to gateways (e.g., identity management or authentication gateways) that provide user account services as part of the intermediary services.
SRG-NET-000519
1 Rule
The ALG providing user access control intermediary services must display an explicit logoff message to users indicating the reliable termination of authenticated communications sessions.
Medium Severity
If a user cannot explicitly end a session, the session may remain open and be exploited by an attacker; this is referred to as a zombie session. Users need to be aware of whether or not the session has been terminated. Logoff messages for access, for example, can be displayed after authenticated sessions have been terminated. However, for some types of interactive sessions including, for example, remote logon, information systems typically send logoff messages as final messages prior to terminating sessions. This policy only applies to ALGs (e.g., identity management or authentication gateways) that provide user account services as part of the intermediary services.
SRG-NET-000521
1 Rule
The ALG providing user access control intermediary services must conceal, via the session lock, information previously visible on the display with a publicly viewable image.
Medium Severity
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system, but does not log out because of the temporary nature of the absence. The session lock is implemented at the point where session activity can be determined. The network element session lock event must include an obfuscation of the display screen so as to prevent other users from reading what was previously displayed. Publicly viewable images can include static or dynamic images, for example, patterns used with screen savers, photographic images, solid colors, a clock, a battery life indicator, or a blank screen, with the additional caveat that none of the images convey sensitive information. This policy only applies to gateways (e.g., identity management or authentication gateways) that provide user account services as part of the intermediary services.
SRG-NET-000700
1 Rule
The ALG must prevent or restrict changes to the configuration of the system under organization-defined circumstances.
Medium Severity
System configuration changes can adversely affect critical system security and privacy functionality. Change restrictions can be enforced through automated mechanisms.
SRG-NET-000705
1 Rule
The ALG must employ organization-defined controls by type of denial of service (DoS) to achieve the DoS objective.
Medium Severity
DoS events can occur due to a variety of internal and external causes, such as an attack by an adversary or a lack of planning to support organizational needs with respect to capacity and bandwidth. Such attacks can occur across a wide range of network protocols (e.g., IPv4, IPv6). A variety of technologies are available to limit or eliminate the origination and effects of DoS events. For example, boundary protection devices can filter certain types of packets to protect system components on internal networks from being directly affected by or the source of DoS attacks. Employing increased network capacity and bandwidth combined with service redundancy also reduces the susceptibility to DoS events.
SRG-NET-000715
1 Rule
The ALG must implement physically or logically separate subnetworks to isolate organization-defined critical system components and functions.
Medium Severity
Separating critical system components and functions from other noncritical system components and functions through separate subnetworks may be necessary to reduce susceptibility to a catastrophic or debilitating breach or compromise that results in system failure. For example, physically separating the command and control function from the in-flight entertainment function through separate subnetworks in a commercial aircraft provides an increased level of assurance in the trustworthiness of critical system functions.
SRG-NET-000735
1 Rule
The ALG must implement antispoofing mechanisms to prevent adversaries from falsifying the security attributes indicating the successful application of the security process.
Medium Severity
Some attack vectors operate by altering the security attributes of an information system to intentionally and maliciously implement an insufficient level of security within the system. The alteration of attributes leads organizations to believe that a greater number of security functions are in place and operational than have actually been implemented.
SRG-NET-000750
1 Rule
The ALG must include only approved trust anchors in trust stores or certificate stores managed by the organization.
Medium Severity
Public key infrastructure (PKI) certificates are certificates with visibility external to organizational systems and certificates related to the internal operations of systems, such as application-specific time services. In cryptographic systems with a hierarchical structure, a trust anchor is an authoritative source (i.e., a certificate authority) for which trust is assumed and not derived. A root certificate for a PKI system is an example of a trust anchor. A trust store or certificate store maintains a list of trusted root certificates.
SRG-NET-000755
1 Rule
The ALG must provide protected storage for cryptographic keys with organization-defined safeguards and/or hardware protected key store.
Medium Severity
A Trusted Platform Module (TPM) is an example of a hardware-protected data store that can be used to protect cryptographic keys.
SRG-NET-000760
1 Rule
The ALG must establish organization-defined alternate communications paths for system operations organizational command and control.
Medium Severity
An incident, whether adversarial- or nonadversarial-based, can disrupt established communications paths used for system operations and organizational command and control. Alternate communications paths reduce the risk of all communications paths being affected by the same incident. To compound the problem, the inability of organizational officials to obtain timely information about disruptions or to provide timely direction to operational elements after a communications path incident, can impact the ability of the organization to respond to such incidents in a timely manner. Establishing alternate communications paths for command and control purposes, including designating alternative decision makers if primary decision makers are unavailable and establishing the extent and limitations of their actions, can greatly facilitate the organization's ability to continue to operate and take appropriate actions during an incident.
SRG-NET-000765
1 Rule
The ALG must implement signature based and/or nonsignature based malicious code protection mechanisms at system entry and exit points to detect and eradicate malicious code.
Medium Severity
System entry and exit points include firewalls, remote access servers, workstations, electronic mail servers, web servers, proxy servers, notebook computers, and mobile devices. Malicious code includes viruses, worms, Trojan horses, and spyware. Malicious code can also be encoded in various formats contained within compressed or hidden files or hidden in files using techniques such as steganography. Malicious code can be inserted into systems in a variety of ways, including by electronic mail, the world wide web, and portable storage devices. Malicious code insertions occur through the exploitation of system vulnerabilities. A variety of technologies and methods exist to limit or eliminate the effects of malicious code. Malicious code protection mechanisms include both signature- and nonsignature-based technologies. Nonsignature-based detection mechanisms include artificial intelligence techniques that use heuristics to detect, analyze, and describe the characteristics or behavior of malicious code and to provide controls against such code for which signatures do not yet exist or for which existing signatures may not be effective. Malicious code for which active signatures do not yet exist or may be ineffective includes polymorphic malicious code (i.e., code that changes signatures when it replicates). Nonsignature-based mechanisms also include reputation-based technologies. In addition to the above technologies, pervasive configuration management, comprehensive software integrity controls, and anti-exploitation software may be effective in preventing the execution of unauthorized code. Malicious code may be present in commercial off-the-shelf software as well as custom-built software and could include logic bombs, backdoors, and other types of attacks that could affect organizational mission and business functions. In situations where malicious code cannot be detected by detection methods or technologies, organizations rely on other types of controls, including secure coding practices, configuration management and control, trusted procurement processes, and monitoring practices to ensure that software does not perform functions other than the functions intended. Organizations may determine that, in response to the detection of malicious code, different actions may be warranted. For example, organizations can define actions in response to malicious code detection during periodic scans, the detection of malicious downloads, or the detection of maliciousness when attempting to open or execute files.
SRG-NET-000770
1 Rule
The ALG must configure malicious code protection mechanisms to send alerts to organization-defined personnel in response to malicious code detection.
Medium Severity
System entry and exit points include firewalls, remote access servers, workstations, electronic mail servers, web servers, proxy servers, notebook computers, and mobile devices. Malicious code includes viruses, worms, Trojan horses, and spyware. Malicious code can also be encoded in various formats contained within compressed or hidden files or hidden in files using techniques such as steganography. Malicious code can be inserted into systems in a variety of ways, including by electronic mail, the world-wide web, and portable storage devices. Malicious code insertions occur through the exploitation of system vulnerabilities. A variety of technologies and methods exist to limit or eliminate the effects of malicious code. Malicious code protection mechanisms include both signature- and nonsignature-based technologies. Nonsignature-based detection mechanisms include artificial intelligence techniques that use heuristics to detect, analyze, and describe the characteristics or behavior of malicious code and to provide controls against such code for which signatures do not yet exist or for which existing signatures may not be effective. Malicious code for which active signatures do not yet exist or may be ineffective includes polymorphic malicious code (i.e., code that changes signatures when it replicates). Nonsignature-based mechanisms also include reputation-based technologies. In addition to the above technologies, pervasive configuration management, comprehensive software integrity controls, and anti-exploitation software may be effective in preventing the execution of unauthorized code. Malicious code may be present in commercial off-the-shelf software as well as custom-built software and could include logic bombs, backdoors, and other types of attacks that could affect organizational mission and business functions. In situations where malicious code cannot be detected by detection methods or technologies, organizations rely on other types of controls, including secure coding practices, configuration management and control, trusted procurement processes, and monitoring practices to ensure that software does not perform functions other than the functions intended. Organizations may determine that, in response to the detection of malicious code, different actions may be warranted. For example, organizations can define actions in response to malicious code detection during periodic scans, the detection of malicious downloads, or the detection of maliciousness when attempting to open or execute files.