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 | CCI-000366 | 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 | 2025-05-16 | |||
Details
Check Text (C-260555r991590_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