Information
The groupmod command can be used to specify which group the root group belongs to. This affects permissions of files that are group owned by the root group.
Using GID 0 for the root group helps prevent root group owned files from accidentally becoming accessible to non-privileged users.
Solution
Run the following command to set the root group's GID to 0 :
# groupmod -g 0 root
Remove any groups other than the root group with GID 0 or assign them a new GID if appropriate.