Cis Ubuntu1604 V200 5 3 6

---
name: cis-ubuntu1604-v200-5-3-6
description: "Ensure SSH LogLevel is appropriate"
category: cis-networking
version: "2.0.0"
author: cyberstrike-official
tags: [cis, ubuntu, linux, ubuntu-16.04, ssh, remote-access]
cis_id: "5.3.6"
cis_benchmark: "CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0"
tech_stack: [ubuntu, linux]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 5.3.6

## Description

`INFO` level is the basic level that only records login activity of SSH users. In many situations, such as Incident Response, it is important to determine when a particular user was active on a system. The logout record can eliminate those users who disconnected, which helps narrow the field.

`VERBOSE` level specifies that login and logout activity as well as the key fingerprint for any SSH key used for login will be logged. This information is important for SSH key management, especially in legacy environments.

## Rationale

SSH provides several logging levels with varying amounts of verbosity. `DEBUG` is specifically not recommended other than strictly for debugging SSH communications since it provides so much data that it is difficult to identify important security information.

## Audit Procedure

### Command Line

Run the following command and verify that output matches `loglevel VERBOSE` or `loglevel INFO`:

```bash
sshd -T -C user=root -C host="$(hostname)" -C addr="$(grep $(hostname) /etc/hosts | awk '{print $1}')" | grep loglevel
```

### Expected Result

```
loglevel VERBOSE or loglevel INFO
```

Run the following command and verify the output matches:

```bash
grep -i 'loglevel' /etc/ssh/sshd_config | grep -Evi '(VERBOSE|INFO)'
```

Nothing should be returned.

## Remediation

### Command Line

Edit the `/etc/ssh/sshd_config` file to set the parameter as follows:

```
LogLevel VERBOSE
```

OR

```
LogLevel INFO
```

## Default Value

LogLevel INFO

## References

1. https://www.ssh.com/ssh/sshd_config/

## CIS Controls

Version 7

6.2 Activate audit logging - Ensure that local logging has been enabled on all systems and networking devices.

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.

## Profile Applicability

- Level 1 - Server
- Level 1 - Workstation

## Assessment Status

Automated