Vulnerability Discussion

If a local interactive user's files are group-owned by a group of which the user is not a member, unintended users may be able to access them.

Check

Verify all files and directories in a local interactive user home directory are group-owned by a group that the user is a member.

Check the group owner of all files and directories in a local interactive user's home directory with the following command:

Note: The example will be for the user "smithj", who has a home directory of "/home/smithj".

$ sudo ls -lLR ///
-rw-r--r-- 1 smithj smithj 18 Mar 5 17:06 file1
-rw-r--r-- 1 smithj smithj 193 Mar 5 17:06 file2
-rw-r--r-- 1 smithj sa 231 Mar 5 17:06 file3

If any files found with a group-owner different from the home directory user private group, determine if the user is a member of that group with the following command:

$ sudo grep smithj /etc/group
sa:x:100:juan,shelley,bob,smithj
smithj:x:521:smithj

If any files or directories are group owned by a group that the directory owner is not a member of, this is a finding.

Fix

Change the group of a local interactive user's files and directories to a group that the interactive user is a member. To change the group owner of a local interactive user's files and directories, use the following command:

Note: The example will be for the user smithj, who has a home directory of "/home/smithj" and is a member of the users group.

$ sudo chgrp smithj /home/smithj/