CIS Level 2 - Linux Guidelines

Instruction steps

Install the UA client

sudo apt update

sudo apt install ubuntu-advantage-tools

Set up the Ubuntu Security Guide

sudo ua enable usg

sudo apt install usg

Check SCAP Content Overview (Security Content Automation Protocol)

sudo oscap info /usr/share/ubuntu-scap-security-guides/1/benchmarks/ssg-ubuntu2204-ds.xml

Auditing an Ubuntu System for DISA-STIG Compliance

sudo usg audit cis_level2_server

The report is generated in /var/lib/usg/

Applying the CIS rules to a set of systems

There are 2 ways to apply CIS rules.

Method 1: directly using usg command - recommend

sudo usg fix cis_level2_server

Method 2: using usg to generate a script and then run the script

sudo usg generate-fix cis_level2_server --output fix.sh

#And then run

./fix.sh

Notes:

• A reboot is required to take effect after applying the fix.
• CIS Level 2 requires /tmp folder to be mounted in a separate partition. Please ensure that the new partition has enough disk space for MetaDefender Core to run.

Running fix for Ubuntu 24.04

When generating the fix script in Ubuntu 24.04, there will be 2 rules (in the generated script - fix.sh) that change the permission and owner of the folder /var/log:

#240: xccdf_org.ssgproject.content_rule_file_groupownerships_var_log

#255: xccdf_org.ssgproject.content_rule_file_ownerships_var_log

These 2 rules will change the permission and owner of the product log also var/log/ometascan .

To prevent this, before running the fix script, the user needs to add metascan group, for example, with rule #240.

group="root"

find -L /var/log/ -type f -regextype posix-extended \

    ! -group root ! -group adm ! -group metascan  \

    ! -name 'gdm' ! -name 'gdm3' \

    ! -name 'sssd' ! -name 'SSSD' \

    ! -name 'auth.log' \

    ! -name 'messages' \

    ! -name 'syslog' \

    ! -path '/var/log/apt/*' \

    ! -path '/var/log/gdm/*' \

    ! -path '/var/log/gdm3/*' \

    ! -path '/var/log/sssd/*' \

    ! -path '/var/log/[bw]tmp*' \

    ! -path '/var/log/cloud-init.log*' \

    ! -regex '.*\.journal[~]?' \

    ! -regex '.*/lastlog(\.[^\/]+)?$' \

    ! -regex '.*/localmessages(.*)' \

    ! -regex '.*/secure(.*)' \

    ! -regex '.*/waagent.log(.*)' \

    -regex '.*' -exec chgrp $group {} \;

Also do the same with rule #255 to prevent update permission and the owner of var/log/ometascan