Cis Ubuntu1804 V220 6 1 9

---
name: cis-ubuntu1804-v220-6-1-9
description: "Ensure permissions on /etc/security/opasswd are configured"
category: cis-iam
version: "2.2.0"
author: cyberstrike-official
tags: [cis, ubuntu, linux, ubuntu-18.04, file-permissions]
cis_id: "6.1.9"
cis_benchmark: "CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0"
tech_stack: [ubuntu, linux]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# 6.1.9 Ensure permissions on /etc/security/opasswd are configured (Automated)

## Profile

- Level 1 - Server
- Level 1 - Workstation

## Description

`/etc/security/opasswd` and its backup `/etc/security/opasswd.old` hold user's previous passwords if `pam_unix` or `pam_pwhistory` is in use on the system.

## Rationale

It is critical to ensure that `/etc/security/opasswd` is protected from unauthorized access. Although it is protected by default, the file permissions could be changed either inadvertently or through malicious actions.

## Audit Procedure

### Command Line

Run the following commands to verify `/etc/security/opasswd` and `/etc/security/opasswd.old` are mode 600 or more restrictive, `Uid` is `0/root` and `Gid` is `0/root` if they exist:

```bash
# [ -e "/etc/security/opasswd" ] && stat -Lc '%n Access: (%#a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/security/opasswd
```

```bash
# [ -e "/etc/security/opasswd.old" ] && stat -Lc '%n Access: (%#a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/security/opasswd.old
```

## Expected Result

```
/etc/security/opasswd Access: (0600/-rw-------) Gid: ( 0/ root) Gid: ( 0/ root)
  -OR-
Nothing is returned
```

```
/etc/security/opasswd.old Access: (0600/-rw-------) Gid: ( 0/ root) Gid: ( 0/ root)
  -OR-
Nothing is returned
```

## Remediation

### Command Line

Run the following commands to remove excess permissions, set owner, and set group on `/etc/security/opasswd` and `/etc/security/opasswd.old` if they exist:

```bash
# [ -e "/etc/security/opasswd" ] && chmod u-x,go-rwx /etc/security/opasswd
# [ -e "/etc/security/opasswd" ] && chown root:root /etc/security/opasswd
# [ -e "/etc/security/opasswd.old" ] && chmod u-x,go-rwx /etc/security/opasswd.old
# [ -e "/etc/security/opasswd.old" ] && chown root:root /etc/security/opasswd.old
```

## Default Value

/etc/security/opasswd Access: (0600/-rw-------) Uid: ( 0/ root) Gid: ( 0/ root)

## References

1. NIST SP 800-53 Rev. 5: AC-3, MP-2

## CIS Controls

- v8: **3.3** Configure Data Access Control Lists
- v7: **14.6** Protect Information through Access Control Lists