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V-270716

CAT II (Medium)

Ubuntu 24.04 LTS default filesystem permissions must be defined in such a way that all authenticated users can read and modify only their own files.

Rule ID

SV-270716r1066637_rule

STIG

Canonical Ubuntu 24.04 LTS Security Technical Implementation Guide

Version

V1R5

CCIs

CCI-000366

Discussion

Setting the most restrictive default permissions ensures that when new accounts are created, they do not have unnecessary access.

Check Content

Verify Ubuntu 24.04 LTS defines default permissions for all authenticated users in such a way that the user can read and modify only their own files with 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 the value of "UMASK" is not set to "077", is commented out, or is missing, this is a finding.

Fix Text

Configure the system to define the default permissions for all authenticated users in such a way that the user can read and modify only their own files. 
 
Edit the "UMASK" parameter in the "/etc/login.defs" file to match the example below: 
 
UMASK 077