Googled: clientarea.php "Powered by WHMCompleteSolution"
Saw, "Page 1 of about 3,080,000 results"
Face palmed<p>Hopefully whoever found this gave them lead time to fix this, or there's going to be a lot of damage done.
For those interested, there is a patch from WHMCS <a href="http://blog.whmcs.com/?t=79427" rel="nofollow">http://blog.whmcs.com/?t=79427</a>