Description

If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following line to a file with suffix .rules in the directory /etc/audit/rules.d for both 32 bit and 64 bit systems:

-a always,exit -F arch=b32 -S stime -F key=audit_time_rules

Since the 64 bit version of the “stime” system call is not defined in the audit lookup table, the corresponding “-F arch=b64” form of this rule is not expected to be defined on 64 bit systems (the aforementioned “-F arch=b32” stime rule form itself is sufficient for both 32 bit and 64 bit systems). If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following line to /etc/audit/audit.rules file for both 32 bit and 64 bit systems:

-a always,exit -F arch=b32 -S stime -F key=audit_time_rules

Since the 64 bit version of the “stime” system call is not defined in the audit lookup table, the corresponding “-F arch=b64” form of this rule is not expected to be defined on 64 bit systems (the aforementioned “-F arch=b32” stime rule form itself is sufficient for both 32 bit and 64 bit systems). The -k option allows for the specification of a key in string form that can be used for better reporting capability through ausearch and aureport. Multiple system calls can be defined on the same line to save space if desired, but is not required. See an example of multiple combined system calls:

-a always,exit -F arch=b64 -S adjtimex,settimeofday -F key=audit_time_rules

Rationale

Arbitrary changes to the system time can be used to obfuscate nefarious activities in log files, as well as to confuse network services that are highly dependent upon an accurate system time (such as sshd). All changes to the system time should be audited.

Remediation

Shell script

The following script can be run on the host to remediate the issue.

#!/bin/bash

<ns10:sub idref="xccdf_org.ssgproject.content_value_function_rhel7_fedora_perform_audit_adjtimex_settimeofday_stime_remediation" use="legacy"/>
rhel7_fedora_perform_audit_adjtimex_settimeofday_stime_remediation