Information
Monitor privileged programs (those that have the setuid and/or setgid bit set on execution) to determine if unprivileged users are running these commands.
Notes:
Systems may have been customized to change the default UID_MIN. To confirm the UID_MIN for your system, run the following command:
# awk '/^s*UID_MIN/{print $2}' /etc/login.defs
If your systems' UID_MIN is not 500, replace audit>=500 with audit>=<UID_MIN for your system> in the Audit and Remediation procedures.
Reloading the auditd configuration to set active settings may require a system reboot.
Rationale:
Execution of privileged commands by non-privileged users could be an indication of someone trying to gain unauthorized access to the system.
NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.
Solution
To remediate this issue, the system administrator will have to execute a find command to locate all the privileged programs and then add an audit line for each one of them.
The audit parameters associated with this are as follows:
-F path=' $1 ' - will populate each file name found through the find command and processed by awk.
-F perm=x - will write an audit record if the file is executed.
-F audit>=500 - will write a record if the user executing the command is not a privileged user.
-F auid!= 4294967295 - will ignore Daemon events
All audit records should be tagged with the identifier 'privileged'.
Run the following command replacing with a list of partitions where programs can be executed from on your system:
# find <partition> -xdev ( -perm -4000 -o -perm -2000 ) -type f | awk '{print '-a always,exit -F path=' $1 ' -F perm=x -F auid>=''$(awk '/^s*UID_MIN/{print $2}' /etc/login.defs)'' -F auid!=4294967295 -k privileged' }'
Edit or create a file in the /etc/audit/rules.d/ directory ending in .rules and add all resulting lines to the file.
Example:
# find / -xdev ( -perm -4000 -o -perm -2000 ) -type f | awk '{print '-a always,exit -F path=' $1 ' -F perm=x -F auid>=''$(awk '/^s*UID_MIN/{print $2}' /etc/login.defs)'' -F auid!=4294967295 -k privileged' }' >> /etc/audit/rules.d/10-privileged.rules