Members of Anonymous faction LulzSec hacked into Panda Security last night for allegedly assisting the FBI in arrests of LulzSec hackers exposed by their former ringleader, Sabu.

Members of Anonymous faction LulzSec attacked Panda Security last night, apparently in retaliation for the arrests of LulzSec hackers exposed by their former ringleader, Sabu.

Over 25 websites belonging to Panda Security went offline overnight and were defaced with messages from Anonymous. The emails, usernames, and passwords of more than a hundred employees were also posted online. The Hacker News has a list of all the defaced sites, mostly marketing-related.

"Pandasecurity.com, better known for its shitty ANTIVIRUS WE HAVE BACKDOORED, has [been] earning money working with Law Enforcement to lurk and snitch on anonymous activists. they helped to jail 25 anonymous in different countries...yep we know about you. How does it feel to be the spied one?" read one of the messages.

In an official statement released Wednesday Panda Security said the hacktivists had only breached an external server storing Panda's marketing campaigns and blogs.

"The attack did not breach Panda Security’s internal network and neither source code, update servers nor customer data was accessed," wrote Pedro Bustamante, senior research advisor for Panda Security. "The only information accessed was related to marketing campaigns such as landing pages and some obsolete credentials, including supposed credentials for employees that have not been working at Panda for over five years."

Panda Security has long publically condemned LulzSec. In fact, Sophos Security's Graham Cluley said last night's perpetrators singled out Luis Corrons, a technical director at PandaLabs, for expressing glee over the arrests. Corrons had published a since-removed blog post asking, "Where is the lulz now?" and had also tweeted, "Lads defending freedom of speech until they don't like what you say #sadlulz."

Last July, Panda published a research paper describing anonymous hacking activities as 'stupidism' rather than 'hacktivism.' The author even singled out LulzSec:

"In my opinion, if you took the most irresponsible and brainless members of Anonymous and put them all together, they would be considered the most refined gentlemen compared to LulzSec," read part of the report, which is now offline due to last night's DDoS attack.

On Tuesday, the FBI charged six members of Anonymous/LulzSec who were based in the U.K., New York, Chicago, and Ireland. In a shocking revelation, it was disclosed that former LulzSec ringleader Sabu (real name: Hector Xavier Monsegur), a 28-year-old single father living in the Lower East Side of Manhattan, New York City, had served as an informant for several months. For a rundown of all the charges, see 'FBI Takes Down LulzSec Hackers, With Help From Inside.'