Ubuntu 22.04 LTS default filesystem permissions must be defined in such a way that all authenticated users can read and modify only their own files.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-260555	UBTU-22-412035	SV-260555r991590_rule		Medium

Description
Setting the most restrictive default permissions ensures newly created accounts do not have unnecessary access.

STIG	Date
Canonical Ubuntu 22.04 LTS Security Technical Implementation Guide	2024-05-30

Details

Check Text ( C-64284r953476_chk )
Verify Ubuntu 22.04 LTS defines default permissions for all authenticated users in such a way that the user can read and modify only their own files by using the following command: $ grep -i '^\s*umask' /etc/login.defs UMASK 077 If the "UMASK" variable is set to "000", this is a finding with the severity raised to a CAT I. If "UMASK" is not set to "077", is commented out, or is missing, this is a finding.

Check Text ( C-64284r953476_chk )

Verify Ubuntu 22.04 LTS defines default permissions for all authenticated users in such a way that the user can read and modify only their own files by using the following command:

$ grep -i '^\s*umask' /etc/login.defs
UMASK 077

If the "UMASK" variable is set to "000", this is a finding with the severity raised to a CAT I.

If "UMASK" is not set to "077", is commented out, or is missing, this is a finding.

Fix Text (F-64192r953477_fix)
Configure Ubuntu 22.04 LTS to define the default permissions for all authenticated users in such a way that the user can read and modify only their own files. Add or modify the following line in the "/etc/login.defs" file: UMASK 077