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.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-219328	UBTU-18-010448	SV-219328r610963_rule		Medium

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

STIG	Date
Canonical Ubuntu 18.04 LTS Security Technical Implementation Guide	2022-12-06

Details

Check Text ( C-21053r305312_chk )
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.

Check Text ( C-21053r305312_chk )

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 (F-21052r305313_fix)
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