cis-ubuntu1204-v110-12-11

name	cis-ubuntu1204-v110-12-11
description	Find SGID System Executables
category	cis-os-hardening
version	1.1.0
author	cyberstrike-official
tags	["cis","ubuntu",12.04,"linux","sgid","file-permissions","privilege-escalation"]
cis_id	12.11
cis_benchmark	CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

12.11 Find SGID System Executables (Not Scored)

Profile Applicability

• Level 1

Description

The owner of a file can set the file's permissions to run with the owner's or group's permissions, even if the user running the program is not the owner or a member of the group. The most common reason for a SGID program is to enable users to perform functions (such as changing their password) that require root privileges.

Rationale

There are valid reasons for SGID programs, but it is important to identify and review such programs to ensure they are legitimate. Review the files returned by the action in the audit section and check to see if system binaries have a different md5 checksum than what from the package. This is an indication that the binary may have been replaced.

Audit Procedure

Using Command Line

#!/bin/bash
df --local -P | awk {'if (NR!=1) print $6'} | xargs -I '{}' find '{}' -xdev -type f -perm -2000 -print

Expected Result

Review the list of SGID executables returned. All SGID files should be legitimate system binaries. Investigate any unexpected or unauthorized SGID files.

Remediation

Using Command Line

Ensure that no rogue set-GID programs have been introduced into the system. Review the files returned by the action in the Audit section and confirm the integrity of these binaries.

Default Value

Various system binaries have SGID set by default (e.g., /usr/bin/wall, /usr/bin/write).

References

• CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0

Profile

Level 1 - Not Scored