Guide to the Secure Configuration of Oracle Linux 8
Rules, Groups, and Values defined within the XCCDF Benchmark
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Ensure that chronyd is running under chrony user account
chrony is a daemon which implements the Network Time Protocol (NTP). It is designed to synchronize system clocks across a variety of systems and use a source that is highly accurate. More informati...Rule Medium Severity -
Verify Group Who Owns /etc/chrony.keys File
To properly set the group owner of/etc/chrony.keys, run the command:$ sudo chgrp chrony /etc/chrony.keys
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 severely limiting the service has been the best a...Group -
Name Service Switch does not use NIS
Each call to a function which retrieves data from a system database like the password or group database is handled by the Name Service Switch implementation in the GNU C library. The various servi...Rule Medium Severity -
Uninstall rsh-server Package
Thersh-serverpackage can be removed with the following command:$ sudo yum erase rsh-server
Rule High Severity -
Remove User Host-Based Authentication Files
The <code>~/.shosts</code> (in each user's home directory) files list remote hosts and users that are trusted by the local system. To remove these files, run the following command to delete them fr...Rule High Severity -
Uninstall telnet-server Package
Thetelnet-serverpackage can be removed with the following command:$ sudo yum erase telnet-server
Rule High Severity -
Uninstall squid Package
Thesquidpackage can be removed with the following command:$ sudo yum erase squid
Rule Unknown Severity -
Disable Quagga Service
Thezebraservice can be disabled with the following command:$ sudo systemctl mask --now zebra.service
Rule Medium Severity -
Uninstall net-snmp Package
Thenet-snmppackage provides the snmpd service. Thenet-snmppackage can be removed with the following command:$ sudo yum erase net-snmp
Rule Unknown Severity -
Disable snmpd Service
Thesnmpdservice 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. The multiple security models implemented by SNMP...Group -
Enable the OpenSSH Service
The SSH server service, sshd, is commonly needed. Thesshdservice can be enabled with the following command:$ sudo systemctl enable sshd.service
Rule Medium Severity -
Verify Group Who Owns SSH Server config file
To properly set the group owner of/etc/ssh/sshd_config, run the command:$ sudo chgrp root /etc/ssh/sshd_config
Rule Medium Severity -
Verify Owner on SSH Server config file
To properly set the owner of/etc/ssh/sshd_config, run the command:$ sudo chown root /etc/ssh/sshd_config
Rule Medium Severity -
Verify Permissions on SSH Server config file
To properly set the permissions of/etc/ssh/sshd_config, run the command:$ sudo chmod 0600 /etc/ssh/sshd_config
Rule Medium Severity -
Remove SSH Server iptables Firewall exception (Unusual)
By default, inbound connections to SSH's port are allowed. If the SSH server is not being used, this exception should be removed from the firewall configuration. <br> <br> Edit the files <co...Rule Unknown Severity -
Configure session renegotiation for SSH client
The <code>RekeyLimit</code> parameter specifies how often the session key is renegotiated, both in terms of amount of data that may be transmitted and the time elapsed. To decrease the default limi...Rule Medium Severity -
Verify the SSH Private Key Files Have a Passcode
When creating SSH key pairs, always use a passcode. <br> You can create such keys with the following command: <pre>$ sudo ssh-keygen -n [passphrase]</pre> Oracle Linux 8, for certificate-based auth...Rule Medium Severity -
Set SSH Client Alive Interval
SSH allows administrators to set a network responsiveness timeout interval. After this interval has passed, the unresponsive client will be automatically logged out. <br> <br> To set this t...Rule Medium Severity -
Disable GSSAPI Authentication
Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms like GSSAPI. <br> The default SSH configuration disallows authentications based on GSSAPI. The appropriate c...Rule Medium Severity -
Disable Kerberos Authentication
Unless needed, SSH should not permit extraneous or unnecessary authentication mechanisms like Kerberos. <br> The default SSH configuration disallows authentication validation through Kerberos. The ...Rule Medium Severity -
Do Not Allow SSH Environment Options
Ensure that users are not able to override environment variables of the SSH daemon. <br> The default SSH configuration disables environment processing. The appropriate configuration is used if no v...Rule Medium Severity -
Enable SSH Print Last Log
Ensure that SSH will display the date and time of the last successful account logon. <br> The default SSH configuration enables print of the date and time of the last login. The appropriate configu...Rule Medium Severity -
Force frequent session key renegotiation
The <code>RekeyLimit</code> parameter specifies how often the session key of the is renegotiated, both in terms of amount of data that may be transmitted and the time elapsed.<br> To decrease the d...Rule Medium Severity -
Use Only FIPS 140-2 Validated Key Exchange Algorithms
Limit the key exchange algorithms to those which are FIPS-approved. Add or modify the following line in <code>/etc/crypto-policies/back-ends/opensshserver.config</code> <pre>CRYPTO_POLICY=...Rule Medium Severity -
Use Only Strong Key Exchange algorithms
Limit the Key Exchange to strong algorithms. The following line in <code>/etc/ssh/sshd_config</code> demonstrates use of those: <pre>KexAlgorithms <xccdf-1.2:sub idref="xccdf_org.ssgproject.content...Rule Medium Severity -
Install sssd-ipa Package
Thesssd-ipapackage can be installed with the following command:$ sudo yum install sssd-ipa
Rule Medium Severity -
Certificate status checking in SSSD
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...Rule Medium Severity -
Enable Smartcards in SSSD
SSSD should be configured to authenticate access to the system using smart cards. To enable smart cards in SSSD, set <code>pam_cert_auth</code> to <code>True</code> under the <code>[pam]</code> sec...Rule Medium Severity -
Configure SSSD to Expire Offline Credentials
SSSD should be configured to expire offline credentials after 1 day. Check if SSSD allows cached authentications with the following command: <pre> $ sudo grep cache_credentials /etc/sssd/sssd.conf...Rule Medium Severity -
Configure SSSD LDAP Backend to Use TLS For All Transactions
The LDAP client should be configured to implement TLS for the integrity of all remote LDAP authentication sessions. If the <code>id_provider</code> is set to <code>ldap</code> or <code>ipa</code> i...Rule High Severity -
Remove the X Windows Package Group
By removing the xorg-x11-server-common package, the system no longer has X Windows installed. If X Windows is not installed then the system cannot boot into graphical user mode. This prevents the s...Rule Medium Severity -
Disable X Windows Startup By Setting Default Target
Systems that do not require a graphical user interface should only boot by default into <code>multi-user.target</code> mode. This prevents accidental booting of the system into a <code>graphical.ta...Rule Medium Severity -
Enable Auditing for Processes Which Start Prior to the Audit Daemon
To ensure all processes can be audited, even those which start prior to the audit daemon, add the argument <code>audit=1</code> to the default GRUB 2 command line for the Linux operating system. To...Rule Low Severity -
Configure auditd Data Retention
The audit system writes data to <code>/var/log/audit/audit.log</code>. By default, <code>auditd</code> rotates 5 logs by size (6MB), retaining a maximum of 30MB of data in total, and refuses to wri...Group -
Audit failure mode
This variable is the setting for the -f option in Audit configuration which sets the failure mode of audit. This option lets you determine how you want the kernel to handle critical errors. Possibl...Value -
Record Events that Modify User/Group Information via open syscall - /etc/group
The audit system should collect write events to /etc/group file for all users and root. If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rule...Rule Medium Severity -
Record Events that Modify User/Group Information via open_by_handle_at syscall - /etc/group
The audit system should collect write events to /etc/group file for all group and root. If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rule...Rule Medium Severity -
Make the auditd Configuration Immutable
If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default), add the following line to a file with suffix <cod...Rule Medium Severity -
Record Events that Modify User/Group Information via open syscall - /etc/gshadow
The audit system should collect write events to /etc/gshadow file for all users and root. If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit ru...Rule Medium Severity -
Record Events that Modify User/Group Information via openat syscall - /etc/gshadow
The audit system should collect write events to /etc/gshadow file for all users and root. If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit ru...Rule Medium Severity -
Record Events that Modify User/Group Information via open syscall - /etc/passwd
The audit system should collect write events to /etc/passwd file for all users and root. If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rul...Rule Medium Severity -
System Audit Logs Must Be Group Owned By Root
All audit logs must be group owned by root user. The path for audit log can be configured via <code>log_file</code> parameter in <pre>/etc/audit/auditd.conf</pre> or, by default, the path for audit...Rule Medium Severity -
Record Events that Modify User/Group Information via openat syscall - /etc/passwd
The audit system should collect write events to /etc/passwd file for all users and root. If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rul...Rule Medium Severity -
Record Events that Modify User/Group Information via open syscall - /etc/shadow
The audit system should collect write events to /etc/shadow file for all users and root. If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rul...Rule Medium Severity -
Record Events that Modify User/Group Information via open_by_handle_at syscall - /etc/shadow
The audit system should collect write events to /etc/shadow file for all users and root. If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rul...Rule Medium Severity -
Record Events that Modify User/Group Information via openat syscall - /etc/shadow
The audit system should collect write events to /etc/shadow file for all users and root. If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rul...Rule Medium Severity -
Record Events that Modify the System's Mandatory Access Controls in usr/share
If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default), add the following line to a file with suffix <cod...Rule Medium Severity -
Record Events that Modify the System's Network Environment
If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default), add the following lines to a file with suffix <co...Rule Medium Severity
Node 2
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