The hacktivist collective Anonymous celebrated Guy Fawkes Day on Monday by claiming it had stolen data from Symantec and ImageShack servers and had found a zero-day flaw in ZPanel.
Fawkes was arrested over an alleged Nov. 5, 1605 botched attempt to blow up the Houses of Parliament in England as part of a plot to restore the Catholic monarchy.
Anonymous has taken as a symbol of its hacktivism the Fawkes mask designed by David Lloyd, illustrator of the "V for Vendetta" comic book series.
Antivirus vendor Symantec denied finding any evidence that customer data was stolen, as claimed by Anonymous.
"Symantec is investigating the recent claims made online regarding the security of our networks," the company said in an emailed statement. "We have found no evidence that customer information was exposed or impacted."
However, Imperva, which specializes in database and application security, said the information leaked by Anonymous "shows with a high degree of confidence that the attackers were able to penetrate an internal database of Symantec."
"Most likely, the Symantec support content management system database," Tal Beery, security researcher for Imperva, said in an email. "[Anonymous] had published the contents of one database, which includes names, email addresses, hashed passwords and some phone numbers of Symantec employees."
Whether Anonymous hacked the servers of ImageShack, an online photo and video sharing service, could not be confirmed independently. The hactivist group claimed to have stolen file permission listings, source codes and other information, but ImageShack did not answer a request for comment.
Meanwhile, initial reports said Anonymous had hacked the online payments site PayPal. Those statements were later corrected, saying they found a vulnerability in ZPanel's password reset functionality. ZPanel makes an open source Web hosting control panel for Microsoft Windows, Linux, Unix and Mac OS X.
Anonymous claimed to find a vulnerability in the open source software's password reset functionality.
In denying it had been hacked, PayPal released a statement via email that said: "It appears that the exploit was not directed at PayPal after all, it was directed at a company called ZPanel. The original story that started this and was re-tweeted by some of the Anonymous Twitter handles has now been updated."
ZPanel could not be reached for comment.
Over the weekend, reports said Anonymous claimed that it would hack Zynga on Nov. 5 and release its games for free download. The group also threatened to takedown Facebook. On Monday, there was no indication either site had been hacked.
Anonymous' claims have sometimes been inflated, while others have been fabrications. In September, AntiSec, an offshoot of Anonymous, claimed it stole information on millions of Apple iPhone and iPad users from an FBI agent's laptop. The boast was later proven false.