Example--Finding Files With setuid Permissions (System Administration Guide, Volume 2)

System Administration Guide, Volume 2

Example--Finding Files With `setuid` Permissions

# find / -user root -perm -4000 -exec ls -ldb {} \; > /tmp/ckprm
# cat /tmp/ckprm
-r-sr-xr-x 1 root bin 38836 Aug 10 16:16 /usr/bin/at
-r-sr-xr-x 1 root bin 19812 Aug 10 16:16 /usr/bin/crontab
---s--x--x 1 root sys 46040 Aug 10 15:18 /usr/bin/ct
-r-sr-xr-x 1 root sys 12092 Aug 11 01:29 /usr/lib/mv_dir
-r-sr-sr-x 1 root bin 33208 Aug 10 15:55 /usr/lib/lpadmin
-r-sr-sr-x 1 root bin 38696 Aug 10 15:55 /usr/lib/lpsched
---s--x--- 1 root rar 45376 Aug 18 15:11 /usr/rar/bin/sh
-r-sr-xr-x 1 root bin 12524 Aug 11 01:27 /usr/bin/df
-rwsr-xr-x 1 root sys 21780 Aug 11 01:27 /usr/bin/newgrp
-r-sr-sr-x 1 root sys 23000 Aug 11 01:27 /usr/bin/passwd
-r-sr-xr-x 1 root sys 23824 Aug 11 01:27 /usr/bin/su
	#

An unauthorized user (rar) has made a personal copy of /usr/bin/sh, and has set the permissions as setuid to root. This means that rar can execute /usr/rar/bin/sh and become the privileged user. If you want to save this output for future reference, move the file out of the /tmp directory.