Cis Ubuntu2004 V300 5 2 3

---
name: cis-ubuntu2004-v300-5-2-3
description: "Ensure sudo log file exists"
category: cis-iam
version: "3.0.0"
author: cyberstrike-official
tags: [cis, ubuntu, linux, ubuntu-20.04, sudo]
cis_id: "5.2.3"
cis_benchmark: "CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0"
tech_stack: [ubuntu, linux]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# Ensure sudo log file exists (Automated)

## Profile Applicability

- Level 1 - Server
- Level 1 - Workstation

## Description

sudo can use a custom log file.

## Rationale

A sudo log file simplifies auditing of sudo commands.

## Impact

WARNING: Editing the `sudo` configuration incorrectly can cause `sudo` to stop functioning. Always use `visudo` to modify `sudo` configuration files.

## Audit Procedure

### Command Line

Run the following command to verify that sudo has a custom log file configured:

```bash
# grep -rPsi "^\h*Defaults\h+([^#]+,\h*)?logfile\h*=\h*(\"|\')?\H+(\"|\')?(,\h*\H+\h*)*\h*(#.*)?$" /etc/sudoers*
```

Verify the output matches:

```
Defaults logfile="/var/log/sudo.log"
```

## Expected Result

```
Defaults logfile="/var/log/sudo.log"
```

## Remediation

### Command Line

Edit the file `/etc/sudoers` or a file in `/etc/sudoers.d/` with `visudo` or `visudo -f <PATH TO FILE>` and add the following line:
Example:

```
Defaults logfile="/var/log/sudo.log"
```

Note:

- sudo will read each file in `/etc/sudoers.d`, skipping file names that end in `~` or contain a `.` character to avoid causing problems with package manager or editor temporary/backup files.
- Files are parsed in sorted lexical order. That is, `/etc/sudoers.d/01_first` will be parsed before `/etc/sudoers.d/10_second`.
- Be aware that because the sorting is lexical, not numeric, `/etc/sudoers.d/1_whoops` would be loaded after `/etc/sudoers.d/10_second`.
- Using a consistent number of leading zeroes in the file names can be used to avoid such problems.

## References

1. SUDO(8)
2. VISUDO(8)
3. sudoers(5)
4. NIST SP 800-53 Rev. 5: AU-3, AU-12

Additional Information:

visudo edits the sudoers file in a safe fashion, analogous to vipw(8). visudo locks the sudoers file against multiple simultaneous edits, provides basic sanity checks, and checks for parse errors. If the sudoers file is currently being edited you will receive a message to try again later.

## CIS Controls

v8 - 8.5 Collect Detailed Audit Logs
Configure detailed audit logging for enterprise assets containing sensitive data. Include event source, date, username, timestamp, source addresses, destination addresses, and other useful elements that could assist in a forensic investigation.

v7 - 6.3 Enable Detailed Logging
Enable system logging to include detailed information such as an event source, date, user, timestamp, source addresses, destination addresses, and other useful elements.

MITRE ATT&CK Mappings: T1562, T1562.006 | TA0004 | M1026