Australian Cyber Security Centre (ACSC) ISM Official
Rules and Groups employed by this XCCDF Profile
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Enable Randomized Layout of Virtual Address Space
To set the runtime status of the <code>kernel.randomize_va_space</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.r...Rule Medium Severity -
SELinux
SELinux is a feature of the Linux kernel which can be used to guard against misconfigured or compromised programs. SELinux enforces the idea that p...Group -
Configure SELinux Policy
The SELinux <code>targeted</code> policy is appropriate for general-purpose desktops and servers, as well as systems in many other roles. To config...Rule Medium Severity -
Ensure SELinux State is Enforcing
The SELinux state should be set to <code><xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_selinux_state" use="legacy"></xccdf-1.2:sub><...Rule High Severity -
SELinux - Booleans
Enable or Disable runtime customization of SELinux system policies without having to reload or recompile the SELinux policy.Group -
Enable the auditadm_exec_content SELinux Boolean
By default, the SELinux boolean <code>auditadm_exec_content</code> is enabled. If this setting is disabled, it should be enabled. To enable the <c...Rule Medium Severity -
Services
The best protection against vulnerable software is running less software. This section describes how to review the software which Red Hat Enterpris...Group -
Avahi Server
The Avahi daemon implements the DNS Service Discovery and Multicast DNS protocols, which provide service and host discovery on a network. It allows...Group -
Disable Avahi Server if Possible
Because the Avahi daemon service keeps an open network port, it is subject to network attacks. Disabling it can reduce the system's vulnerability t...Group -
Disable Avahi Server Software
Theavahi-daemon
service can be disabled with the following command:$ sudo systemctl mask --now avahi-daemon.service
Rule Medium Severity -
Application Whitelisting Daemon
Fapolicyd (File Access Policy Daemon) implements application whitelisting to decide file access rights. Applications that are known via a reputatio...Group -
Install fapolicyd Package
Thefapolicyd
package can be installed with the following command:$ sudo dnf install fapolicyd
Rule Medium Severity -
Enable the File Access Policy Service
The File Access Policy service should be enabled. The <code>fapolicyd</code> service can be enabled with the following command: <pre>$ sudo system...Rule Medium Severity -
Network Time Protocol
The Network Time Protocol is used to manage the system clock over a network. Computer clocks are not very accurate, so time will drift unpredictabl...Group -
The Chrony package is installed
System time should be synchronized between all systems in an environment. This is typically done by establishing an authoritative time server or se...Rule Medium Severity -
The Chronyd service is enabled
chrony is a daemon which implements the Network Time Protocol (NTP) is designed to synchronize system clocks across a variety of systems and use a ...Rule Medium Severity -
A remote time server for Chrony is configured
<code>Chrony</code> is a daemon which implements the Network Time Protocol (NTP). It is designed to synchronize system clocks across a variety of s...Rule Medium Severity -
Obsolete Services
This section discusses a number of network-visible services which have historically caused problems for system security, and for which disabling or...Group -
NIS
The Network Information Service (NIS), also known as 'Yellow Pages' (YP), and its successor NIS+ have been made obsolete by Kerberos, LDAP, and oth...Group -
Remove NIS Client
The Network Information Service (NIS), formerly known as Yellow Pages, is a client-server directory service protocol used to distribute system conf...Rule Unknown Severity -
Rlogin, Rsh, and Rexec
The Berkeley r-commands are legacy services which allow cleartext remote access and have an insecure trust model.Group -
Uninstall rsh-server Package
Thersh-server
package can be removed with the following command:$ sudo dnf erase rsh-server
Rule High Severity -
Uninstall rsh Package
Thersh
package contains the client commands for the rsh servicesRule Unknown Severity -
Chat/Messaging Services
The talk software makes it possible for users to send and receive messages across systems through a terminal session.Group -
Uninstall talk-server Package
Thetalk-server
package can be removed with the following command:$ sudo dnf erase talk-server
Rule Medium Severity -
Uninstall talk Package
The <code>talk</code> package contains the client program for the Internet talk protocol, which allows the user to chat with other users on differe...Rule Medium Severity -
Telnet
The telnet protocol does not provide confidentiality or integrity for information transmitted on the network. This includes authentication informat...Group -
Uninstall telnet-server Package
Thetelnet-server
package can be removed with the following command:$ sudo dnf erase telnet-server
Rule High Severity -
Remove telnet Clients
The telnet client allows users to start connections to other systems via the telnet protocol.Rule Low Severity -
Disable telnet Service
Make sure that the activation of the <code>telnet</code> service on system boot is disabled. The <code>telnet</code> socket can be disabled with t...Rule High Severity -
Proxy Server
A proxy server is a very desirable target for a potential adversary because much (or all) sensitive data for a given infrastructure may flow throug...Group -
Disable Squid if Possible
If Squid was installed and activated, but the system does not need to act as a proxy server, then it should be disabled and removed.Group -
Uninstall squid Package
Thesquid
package can be removed with the following command:$ sudo dnf erase squid
Rule Unknown Severity -
Disable Squid
Thesquid
service can be disabled with the following command:$ sudo systemctl mask --now squid.service
Rule Unknown Severity -
Network Routing
A router is a very desirable target for a potential adversary because they fulfill a variety of infrastructure networking roles such as access to ...Group -
Disable Quagga if Possible
If Quagga was installed and activated, but the system does not need to act as a router, then it should be disabled and removed.Group -
Uninstall quagga Package
Thequagga
package can be removed with the following command:$ sudo dnf erase quagga
Rule Low Severity -
SNMP Server
The Simple Network Management Protocol allows administrators to monitor the state of network devices, including computers. Older versions of SNMP w...Group -
Disable SNMP Server if Possible
The system includes an SNMP daemon that allows for its remote monitoring, though it not installed by default. If it was installed and activated but...Group -
Disable snmpd Service
Thesnmpd
service can be disabled with the following command:$ sudo systemctl mask --now snmpd.service
Rule Low Severity -
Configure SNMP Server if Necessary
If it is necessary to run the snmpd agent on the system, some best practices should be followed to minimize the security risk from the installation...Group -
Configure SNMP Service to Use Only SNMPv3 or Newer
Edit <code>/etc/snmp/snmpd.conf</code>, removing any references to <code>rocommunity</code>, <code>rwcommunity</code>, or <code>com2sec</code>. Upo...Rule Medium Severity -
SSH Server
The SSH protocol is recommended for remote login and remote file transfer. SSH provides confidentiality and integrity for data exchanged between tw...Group -
Verify Permissions on SSH Server Private *_key Key Files
SSH server private keys - files that match the <code>/etc/ssh/*_key</code> glob, have to have restricted permissions. If those files are owned by t...Rule Medium Severity -
Configure OpenSSH Server if Necessary
If the system needs to act as an SSH server, then certain changes should be made to the OpenSSH daemon configuration file <code>/etc/ssh/sshd_confi...Group -
Disable Host-Based Authentication
SSH's cryptographic host-based authentication is more secure than <code>.rhosts</code> authentication. However, it is not recommended that hosts un...Rule Medium Severity -
Enable SSH Server firewalld Firewall Exception
If the SSH server is in use, inbound connections to SSH's port should be allowed to permit remote access through SSH. In more restrictive firewalld...Rule Medium Severity -
Allow Only SSH Protocol 2
Only SSH protocol version 2 connections should be permitted. The default setting in <code>/etc/ssh/sshd_config</code> is correct, and can be verifi...Rule High Severity -
Disable SSH Access via Empty Passwords
Disallow SSH login with empty passwords. The default SSH configuration disables logins with empty passwords. The appropriate configuration is used ...Rule High Severity -
Disable GSSAPI Authentication
Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms like GSSAPI. <br> The default SSH configuration disallows ...Rule Medium Severity
Node 2
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