cis-ubuntu1604-v200-6-1-11

name	cis-ubuntu1604-v200-6-1-11
description	Ensure no unowned files or directories exist
category	cis-storage
version	2.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-16.04","file-permissions","maintenance"]
cis_id	6.1.11
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 - 6.1.11

Profile Applicability

• Level 1 - Server
• Level 1 - Workstation

Description

Sometimes when administrators delete users from the password file they neglect to remove all files owned by those users from the system.

Rationale

A new user who is assigned the deleted user's user ID or group ID may then end up "owning" these files, and thus have more access on the system than was intended.

Audit Procedure

Command Line

Run the following command and verify no files are returned:

df --local -P | awk '{if (NR!=1) print $6}' | xargs -I '{}' find '{}' -xdev -nouser

The command above only searches local filesystems, there may still be compromised items on network mounted partitions. Additionally the --local option to df is not universal to all versions, it can be omitted to search all filesystems on a system including network mounted filesystems or the following command can be run manually for each partition:

find <partition> -xdev -nouser

Expected Result

No output should be returned.

Remediation

Command Line

Locate files that are owned by users or groups not listed in the system configuration files, and reset the ownership of these files to some active user on the system as appropriate.

Default Value

Not applicable.

References

1. CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0

CIS Controls

Controls Version	Control
v7	13.2 Remove Sensitive Data or Systems Not Regularly Accessed by Organization Remove sensitive data or systems not regularly accessed by the organization from the network. These systems shall only be used as stand alone systems (disconnected from the network) by the business unit needing to occasionally use the system or completely virtualized and powered off until needed.

Assessment Status

Automated