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V-238209

CAT II (Medium)

The Ubuntu operating system 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-238209r991590_rule

STIG

Canonical Ubuntu 20.04 LTS Security Technical Implementation Guide

Version

V2R4

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 the Ubuntu operating system defines default permissions for all authenticated users in such a way that the user can read and modify only their own files. 
 
Verify the Ubuntu operating system defines default permissions for all authenticated users with the following command:  
 
$ grep -i "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 completely, 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