4.1.3.17 Ensure successful and unsuccessful attempts to use the chacl command are recorded

Information

The operating system must generate audit records for successful/unsuccessful uses of the chacl command

Rationale:

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).

Solution

Create audit rules

Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension, with the relevant rules to monitor successful and unsuccessful attempts to use the chacl command.

64 Bit systems

Example:

# {
UID_MIN=$(awk '/^s*UID_MIN/{print $2}' /etc/login.defs)
[ -n '${UID_MIN}' ] && printf '
-a always,exit -F path=/usr/bin/chacl -F perm=x -F auid>=${UID_MIN} -F auid!=unset -k perm_chng
' >> /etc/audit/rules.d/50-perm_chng.rules
|| printf 'ERROR: Variable 'UID_MIN' is unset.
'
}

Load audit rules

Merge and load the rules into active configuration:

# augenrules --load

Check if reboot is required.

# if [[ $(auditctl -s | grep 'enabled') =~ '2' ]]; then printf 'Reboot required to load rules
'; fi

32 Bit systems

Follow the same procedures as for 64 bit systems and ignore any entries with b64.

Additional Information:

Potential reboot required

If the auditing configuration is locked (-e 2), then augenrules will not warn in any way that rules could not be loaded into the running configuration. A system reboot will be required to load the rules into the running configuration.

System call structure

For performance (man 7 audit.rules) reasons it is preferable to have all the system calls on one line. However, your configuration may have them on one line each or some other combination. This is important to understand for both the auditing and remediation sections as the examples given are optimized for performance as per the man page.

See Also

https://workbench.cisecurity.org/files/3807

Item Details

Category: AUDIT AND ACCOUNTABILITY

References: 800-53|AU-2, 800-53|AU-7, 800-53|AU-12, CSCv7|6.2

Plugin: Unix

Control ID: dde0efaeb90509043214dd68082c1b50cb7718f1b43dd68ac2036301a544f645