# Ensure No Duplicate User Names Exist on the System

- Source: https://support.icompaas.com/support/solutions/articles/62000235393-ensure-no-duplicate-user-names-exist-on-the-system
- Section: [Solutions](https://support.icompaas.com/support/solutions) › [CIS Amazon Linux 2 Benchmark v3.0.0](https://support.icompaas.com/support/solutions/62000112696) › [CIS Amazon Linux 2 Benchmarks](https://support.icompaas.com/support/solutions/folders/62000169265)
- Last updated: 2026-05-29
- Publisher: iCompaas, Inc. (https://www.icompaas.com)

Profile Applicability:  
Level 1

  

Description:  
 Duplicate user names can cause conflicts in authentication, permissions, and auditing. Ensuring unique user names maintains system integrity and prevents unauthorized access or privilege escalation.

Rationale:  
 Preventing duplicate user names avoids confusion in user management and reduces risks related to identity and access control.

**Impact:  
** **Pros:**

-   Maintains clear and consistent user identity management.
    
-   Simplifies auditing and access control.
    

**Cons:**

-   Renaming or removing duplicate user accounts may disrupt workflows if not carefully handled.
    

Default Value:  
 Duplicate user names may exist due to misconfiguration or manual errors.

Pre-requisites:

-   Root or sudo privileges to review and modify user accounts.  
    

Remediation:

### Test Plan:

Using Linux command line:

1.  List all user names and identify duplicates:
    
    cut -d: -f1 /etc/passwd | sort | uniq -d
    
2.  Verify that the output is empty, indicating no duplicates.  
    

Implementation Plan:

Using Linux command line:

1.  For each duplicate user name found, rename or remove duplicates carefully:
    
    usermod -l <new\_username> <old\_username>  
    userdel <duplicate\_username>  
    
2.  Ensure user files and permissions are updated accordingly.  
    

Backout Plan:

Using Linux command line:

1.  Restore original user names from backups if needed.
    
2.  Reassign ownership of files and permissions if necessary.  
    

References:

-   CIS Amazon Linux 2 Benchmark v3.0.0
    
-   [NIST SP 800-53 Revision 5 - AC-6  
      
    ](https://csrc.nist.gov/publications/detail/sp/800-53/rev-5/final#ac-6)

## Related compliance guidance

- [SOC 2 compliance: a practical implementation guide for cloud-native SaaS teams](https://support.icompaas.com/compliance/soc-2-trust-services-criteria): Configuration checks like this one are the technical half of a SOC 2 / ISO 27001 programme — the guide shows where they fit, what else an auditor expects, and how to evidence them.
- [ISO/IEC 27001:2022 compliance: a practical implementation guide](https://support.icompaas.com/compliance/iso-27001-2022): ISO 27001 Annex A.8 (technological controls) is where cloud hardening evidence lands; the guide shows how to run the ISMS around it.