cis-ubuntu2004-v300-6-3-3-2

name	cis-ubuntu2004-v300-6-3-3-2
description	Ensure actions as another user are always logged
category	cis-logging
version	3.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-20.04","auditing","auditd"]
cis_id	6.3.3.2
cis_benchmark	CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

6.3.3.2 Ensure actions as another user are always logged (Automated)

Profile

• Level 2 - Server
• Level 2 - Workstation

Description

sudo provides users with temporary elevated privileges to perform operations, either as the superuser or another user.

Rationale

Creating an audit log of users with temporary elevated privileges and the operation(s) they performed is essential to reporting. Administrators will want to correlate the events written to the audit trail with the records written to sudo's logfile to verify if unauthorized commands have been executed.

Audit Procedure

Command Line

On disk configuration - Run the following command to check the on disk rules:

# awk '/^ *-a *always,exit/ \
&&/ -F *arch=b(32|64)/ \
&&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
&&(/ -C *euid!=uid/||/ -C *uid!=euid/) \
&&/ -S *execve/ \
&&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules

Verify the output matches:

-a always,exit -F arch=b64 -C euid!=uid -F auid!=unset -S execve -k user_emulation
-a always,exit -F arch=b32 -C euid!=uid -F auid!=unset -S execve -k user_emulation

Running configuration - Run the following command to check loaded rules:

# auditctl -l | awk '/^ *-a *always,exit/ \
&&/ -F *arch=b(32|64)/ \
&&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
&&(/ -C *euid!=uid/||/ -C *uid!=euid/) \
&&/ -S *execve/ \
&&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'

Verify the output matches:

-a always,exit -F arch=b64 -S execve -C uid!=euid -F auid!=-1 -F key=user_emulation
-a always,exit -F arch=b32 -S execve -C uid!=euid -F auid!=-1 -F key=user_emulation

Expected Result

Both on disk and running configuration should show execve rules tracking user emulation.

Remediation

Command Line

Create audit rules - Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension, with the relevant rules to monitor elevated privileges.

Example:

# printf "
-a always, -F =b64 -C euid!=uid -F auid!= -S execve -k user_emulation
-a always, -F =b32 -C euid!=uid -F auid!= -S execve -k user_emulation