The time synchronization configuration file (such as /etc/ntp.conf) must not have an extended ACL.

From Oracle Linux 5 Security Technical Implementation Guide

Associated with: CCI-000225

SV-63177r1_rule The time synchronization configuration file (such as /etc/ntp.conf) must not have an extended ACL.

Vulnerability discussion

A synchronized system clock is critical for the enforcement of time-based policies and the correlation of logs and audit records with other systems. If an illicit time source is used for synchronization, the integrity of system logs and the security of the system could be compromised. If the configuration files controlling time synchronization are not protected, unauthorized modifications could result in the failure of time synchronization.

Check content

Check the NTP configuration file has no extended ACL. # ls -l /etc/ntp.conf If the permissions include a '+', the file has an extended ACL. If the file has an extended ACL and it has not been documented with the IAO, this is a finding.

Fix text

Remove the extended ACL from the NTP configuration file. # setfacl --remove-all /etc/ntp.conf

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