Hackers targeted Stratfor, a global intelligence company, but it was unclear Sunday evening whether the breach and apparent release of credit card information was the work of the group Anonymous.
In a posting on the website Pastebin, hackers said they released Stratfor subscriber data, including information on 4,000 credit cards as well as the company's "private client" list. The posting cited AntiSec, a web-based collaboration with the activist hacking groups Anonymous and LulzSec.
U.S.-based Stratfor, which provides independent analysis of international affairs and security threats, sent an e-mail to subscribers on Sunday:
"On December 24th an unauthorized party disclosed personally identifiable information and related credit card data of some of our members. We have reason to believe that your personal and credit card data could have been included in the information that was illegally obtained and disclosed."
But Stratfor also said the "private clients" disclosure was "merely a list of some of the members that have purchased our publications and does not comprise a list of individuals or entities that have a relationship with Stratfor beyond their purchase of our subscription-based publications."
The security think tank provides intelligence reports to subscribers. A recent e-mail discussed political prospects for Iraq.
A press release on the information-sharing website Pastebin, which said it was by Anonymous, said the group had nothing to do with the cyberattack on Stratfor.
"Stratfor is an open source intelligence agency, publishing daily reports on data collected from the open internet," the purported posting by Anonymous said. "Hackers claiming to be Anonymous have distorted this truth in order to further their hidden agenda, and some Anons have taken the bait."
"The leaked client list represents subscribers to a daily publication which is the primary service of Stratfor," according to the writer. "Stratfor analysts are widely considered to be extremely unbiased. Anonymous does not attack media sources."
Stratfor CEO George Friedman said the company is working closely with law enforcement.
"Stratfor's relationship with its members and, in particular, the confidentiality of their subscriber information, are very important to Stratfor and me," he wrote on the firm's Facebook page.
"We have reason to believe that the names of our corporate subscribers have been posted on other web sites," the Austin, Texas, company said. "We are diligently investigating the extent to which subscriber information may have been obtained."
Asked about the hacking, Pentagon spokesman George Little on Sunday said, "Initial indications suggest that there has been no impact to the DoD (Department of Defense) grid."
Stratfor's website was not functioning Sunday evening. A banner read, "Site is currently undergoing maintenance. Please check back soon."
Hackers in weekend online postings regarding the Stratfor situation mentioned Army Pfc. Bradley Manning, who served as an intelligence analyst in Iraq. He faces 22 charges in connection to the leak of nearly 750,000 U.S. military and State Department documents. Most of them ended up on the WikiLeaks website.
"While the rich and powerful are enjoying themselves with all their bourgeois gifts and lavish meals, our comrade Bradley Manning is not having that great of a time in federal custody," the hackers wrote in a Pastebin posting. "Instead of being heralded as a fighter for free information and government transparency, he is criminalized, marginalized, and incarcerated, threatened with life imprisonment."