The main page or website is not affected by this breach. Hacker managed to upload a html file "b0x.html" in the image directory of WHMCS documentation website(docs.whmcs.com).
Hacker didn't leave any message other than "b0x" in the defacement page. Whenever main page of a website is not defaced, it will take time to admin to notice it. So, we are still able to see the defacement at "http://docs.whmcs.com/images/b0x.html".
Hacker also provided mirror of the defacement " http://zone-h.org/mirror/id/21518159".
This is not the first time WHMCS being victim of hackers attack. In 2012, the infamous UGNazi hacker group break into WHMCS using Social Engineering attack.
Update:
"Our system admin team just evaluated the server and b0x.html had a timestamp dating back to 2012. At the current time it is our belief that this was the result of a previous vulnerability related to mediawiki and no defacement has taken place." WHMCS representatives told Softpedia.
