System executables are stored in the following directories by default:
/bin
/sbin
/usr/bin
/usr/sbin
/usr/local/bin
/usr/local/sbin
These directories should not be group-writable or world-writable.
If any directory DIR in these directories is found to be
group-writable or world-writable, correct its permission with the
following command:
$ sudo chmod go-w DIR