You need to experiment with using the find command and the perm
parameter from the root account, i.e. not user, but including group
and other, e.g. from the '/' directory execute:
# find . -perm 077 -print

I don't know if that will work, but you should read the man page for
the find command, and experiment in a new test directory and simply
touch new files into existence with different permissions between,
root, group, and other by using the chmod and chgrp commands to
permutate the different permissions of file combinations that can
exist - there aren't that many.

If you do that, I know you will be able to sort things out for yourself!