The data leak contains 500,000 records including customer credit card details, username, passwords and IP addresses.
According to report, The hackers tricked WHMCS's own hosting firm into handing over admin credentials to its servers.
UGNazi also gained access to WHMCS's Twitter account, which it used to publicise a series of posts on Pastebin that contained links to locations from which the billing firm's customer records and other sensitive data might be downloaded.
"Following an initial investigation I can report that what occurred today was the result of a social engineering attack. The person was able to impersonate myself with our web hosting company, and provide correct answers to their verification questions," Matt Pugh, WHMCS founder and lead developer explained.
“And thereby gain access to our client account with the host, and ultimately change the email and then request a mailing of the access details. This means that there was no actual hacking of our server. They were ultimately given the access details.”
Hacktivists justified the attack by making unsubstantiated accusations that WHMCS offered services to shady characters, via an update to WHMCS's compromised Twitter feed:
Many websites use WHMCS for scams. You ignored our warnings. We spoke louder. We are watching; and will continue to be watching. #UGNazi
After the incident, WHMCS reported the breach on its systems to the FBI.
