Cis Ubuntu1404 V210 4 1 10

---
name: "CIS Ubuntu 14.04 LTS - 4.1.10 Ensure discretionary access control permission modification events are collected"
description: "Collect audit events for file permission, ownership, and attribute changes"
category: "cis-os-hardening"
version: "2.1.0"
author: "cyberstrike-official"
tags:
  - cis
  - ubuntu
  - ubuntu-14.04
  - level-2
  - scored
  - auditd
  - permissions
  - logging
cis_id: "4.1.10"
cis_benchmark: "CIS Ubuntu Linux 14.04 LTS Benchmark v2.1.0"
tech_stack:
  - ubuntu
  - linux
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: "medium"
---

# 4.1.10 Ensure discretionary access control permission modification events are collected (Scored)

## Profile Applicability

- Level 2 - Server
- Level 2 - Workstation

## Description

Monitor changes to file permissions, attributes, ownership and group. The parameters in this section track changes for system calls that affect file permissions and attributes. The `chmod`, `fchmod` and `fchmodat` system calls affect the permissions associated with a file. The `chown`, `fchown`, `fchownat` and `lchown` system calls affect owner and group attributes on a file. The `setxattr`, `lsetxattr`, `fsetxattr` (set extended file attributes) and `removexattr`, `lremovexattr`, `fremovexattr` (remove extended file attributes) control extended file attributes. In all cases, an audit record will only be written for non-system user ids (auid >= 1000) and will ignore Daemon events (auid = 4294967295). All audit records will be tagged with the identifier "perm_mod."

## Rationale

Monitoring for changes in file attributes could alert a system administrator to activity that could indicate intruder activity or policy violation.

## Audit Procedure

On a 32 bit system run the following commands:

```bash
grep perm_mod /etc/audit/audit.rules
auditctl -l | grep perm_mod
```

Verify output of both matches:

```
-a always,exit -F arch=b32 -S chmod -S fchmod -S fchmodat -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S chown -S fchown -S fchownat -S lchown -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S setxattr -S lsetxattr -S fsetxattr -S removexattr -S lremovexattr -S fremovexattr -F auid>=1000 -F auid!=4294967295 -k perm_mod
```

On a 64 bit system run the following commands:

```bash
grep perm_mod /etc/audit/audit.rules
auditctl -l | grep perm_mod
```

Verify output of both matches:

```
-a always,exit -F arch=b64 -S chmod -S fchmod -S fchmodat -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S chmod -S fchmod -S fchmodat -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S chown -S fchown -S fchownat -S lchown -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S chown -S fchown -S fchownat -S lchown -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S setxattr -S lsetxattr -S fsetxattr -S removexattr -S lremovexattr -S fremovexattr -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S setxattr -S lsetxattr -S fsetxattr -S removexattr -S lremovexattr -S fremovexattr -F auid>=1000 -F auid!=4294967295 -k perm_mod
```

## Expected Result

The audit rules for perm_mod should be present and active.

## Remediation

For 32 bit systems add the following lines to the `/etc/audit/audit.rules` file:

```bash
-a always,exit -F arch=b32 -S chmod -S fchmod -S fchmodat -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S chown -S fchown -S fchownat -S lchown -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S setxattr -S lsetxattr -S fsetxattr -S removexattr -S lremovexattr -S fremovexattr -F auid>=1000 -F auid!=4294967295 -k perm_mod
```

For 64 bit systems add the following lines to the `/etc/audit/audit.rules` file:

```bash
-a always,exit -F arch=b64 -S chmod -S fchmod -S fchmodat -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S chmod -S fchmod -S fchmodat -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S chown -S fchown -S fchownat -S lchown -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S chown -S fchown -S fchownat -S lchown -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b64 -S setxattr -S lsetxattr -S fsetxattr -S removexattr -S lremovexattr -S fremovexattr -F auid>=1000 -F auid!=4294967295 -k perm_mod
-a always,exit -F arch=b32 -S setxattr -S lsetxattr -S fsetxattr -S removexattr -S lremovexattr -S fremovexattr -F auid>=1000 -F auid!=4294967295 -k perm_mod
```

**Notes:** Reloading the auditd config to set active settings may require a system reboot.

## Default Value

Not configured by default.

## References

1. CIS Controls v6.1 - 3.6 Implement Automated Configuration Monitoring System

## Profile

- Level 2 - Server
- Level 2 - Workstation