4.1.11 Ensure use of privileged commands is collected

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:

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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
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If your systems' UID_MIN is not 1000, replace audit>=1000 with audit>=<UID_MIN for your system> in the Audit and Remediation procedures.

-

Reloading the auditd config to set active settings may require a system reboot.

Execution of privileged commands by non-privileged users could be an indication of someone trying to gain unauthorized access to the system.

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 auid>=1000 - 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 inrules 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/privileged.rules

See Also

https://workbench.cisecurity.org/benchmarks/8498