Ubuntu 24.04 LTS must prevent all software from executing at higher privilege levels than users executing the software and the audit system must be configured to audit the execution of privileged functions.

STIG ID: UBTU-24-200580  |  SRG: SRG-OS-000326-GPOS-00126 |  Severity: medium |  CCI: CCI-002233,CCI-002234,CCI-004188 |  Vulnerability Id: V-270689

Vulnerability Discussion

In certain situations, software applications/programs need to execute with elevated privileges to perform required functions. However, if the privileges required for execution are at a higher level than the privileges assigned to organizational users invoking such applications/programs, those users are indirectly provided with greater privileges than assigned by the organizations.

Some programs and processes are required to operate at a higher privilege level and therefore, must be excluded from the organization-defined software list after review.

Satisfies: SRG-OS-000326-GPOS-00126, SRG-OS-000327-GPOS-00127, SRG-OS-000755-GPOS-00220

Check

Verify Ubuntu 24.04 LTS audits the execution of privilege functions by auditing the "execve" system call with the following command:

$ sudo auditctl -l | grep execve
-a always,exit -F arch=b64 -S execve -C uid!=euid -F euid=0 -F key=execpriv
-a always,exit -F arch=b64 -S execve -C gid!=egid -F egid=0 -F key=execpriv
-a always,exit -F arch=b32 -S execve -C uid!=euid -F euid=0 -F key=execpriv
-a always,exit -F arch=b32 -S execve -C gid!=egid -F egid=0 -F key=execpriv

If the command does not return lines that match the example or the lines are commented out, this is a finding.

Notes:
- For 32-bit architectures, only the 32-bit specific output lines from the commands are required.
- The "-k" allows for specifying an arbitrary identifier, and the string after it does not need to match the example output above.

Fix

Configure Ubuntu 24.04 LTS to audit the execution of all privileged functions.

Add or update the following rules in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F arch=b64 -S execve -C uid!=euid -F euid=0 -F key=execpriv
-a always,exit -F arch=b64 -S execve -C gid!=egid -F egid=0 -F key=execpriv
-a always,exit -F arch=b32 -S execve -C uid!=euid -F euid=0 -F key=execpriv
-a always,exit -F arch=b32 -S execve -C gid!=egid -F egid=0 -F key=execpriv

Notes: For 32-bit architectures, only the 32-bit specific entries are required.

To reload the rules file, issue the following command:

$ sudo augenrules --load
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