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V-219328

CAT II (Medium)

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

Rule ID

SV-219328r991590_rule

STIG

Canonical Ubuntu 18.04 LTS Security Technical Implementation Guide

Version

V2R15

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 only read and modify their own files.

Check that 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", "UMASK" is commented out or "UMASK" 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 only read and modify their own files.

Edit the "UMASK" parameter in the "/etc/login.defs" file to match the example below:

UMASK 077