If the Group Identifier (GID) of a local interactive user’s home directory is not the same as the primary GID of the user, this would allow unauthorized access to the user’s files. Users that share the same group may not be able to access files to which they legitimately should have access.
Check
Verify the assigned home directory of all local interactive users is group-owned by that user’s primary GID with the following command.
Note: This may miss local interactive users that have been assigned a privileged User Identifier (UID). Evidence of interactive use may be obtained from a number of log files containing system logon information. The returned directory "/home/smithj" is used as an example.
$ sudo ls -ld $(awk -F: '($3>=1000)&&($1!="nobody"){print $6}' /etc/passwd)
drwxr-x--- 2 smithj admin 4096 Jun 5 12:41 smithj
Check the user's primary group with the following command: