| name | CIS Ubuntu 14.04 LTS - 6.2.17 Ensure no duplicate GIDs exist |
| description | Verify no duplicate Group IDs exist in /etc/group |
| category | cis-os-hardening |
| version | 2.1.0 |
| author | cyberstrike-official |
| tags | ["cis","ubuntu","ubuntu-14.04","level-1","scored","user-accounts"] |
| cis_id | 6.2.17 |
| cis_benchmark | CIS Ubuntu Linux 14.04 LTS Benchmark v2.1.0 |
| tech_stack | ["ubuntu","linux"] |
| cwe_ids | [] |
| chains_with | [] |
| prerequisites | [] |
| severity_boost | medium |
6.2.17 Ensure no duplicate GIDs exist (Scored)
Profile Applicability
- Level 1 - Server
- Level 1 - Workstation
Description
Although the groupadd program will not let you create a duplicate Group ID (GID), it is possible for an administrator to manually edit the /etc/group file and change the GID field.
Rationale
User groups must be assigned unique GIDs for accountability and to ensure appropriate access protections.
Audit Procedure
Run the following script and verify no results are returned:
#!/bin/bash
cat /etc/group | cut -f3 -d":" | sort -n | uniq -c | while read x ; do
[ -z "${x}" ] && break
set - $x
if [ $1 -gt 1 ]; then
groups=`awk -F: '($3 == n) { print $1 }' n=$2 /etc/group | xargs`
echo "Duplicate GID ($2): ${groups}"
fi
done
Expected Result
No output should be returned.
Remediation
Based on the results of the audit script, establish unique GIDs and review all files owned by the shared GID to determine which group they are supposed to belong to.
Default Value
Not applicable.
Notes
You can also use the grpck command to check for other inconsistencies in the /etc/group file.
References
None
CIS Controls
16 Account Monitoring and Control - Account Monitoring and Control
Profile
