Mike Segar/Reuters

The online activist group known as Anonymous, which has targeted opponents of the Occupy Wall Street movement and businesses that stopped providing services to WikiLeaks, has set its sights on a new adversary: media executives.

In protest of antipiracy legislation currently being considered by Congress, the group has posted online documents that reveal personal information about Jeffrey L. Bewkes, chairman and chief executive of Time Warner, and Sumner M. Redstone, who controls Viacom and the CBS Corporation. Those companies, like almost every major company in the media and entertainment industry, have championed the Stop Online Piracy Act, the House of Representatives bill, known as SOPA, and its related Senate bill, called Protect I.P.

The documents, culled from various databases, included Mr. Bewkes’s home addresses and phone numbers, and encouraged users to bombard the company and its executives with e-mails, faxes and phone calls. Mr. Bewkes has received intimidating phone calls and a barrage of e-mails, according to supporters of the legislation who have knowledge about the matter but are not authorized to discuss the matter publicly.

The documents also included the corporate contact information for a range of companies including NBCUniversal, Sony Pictures Entertainment and the Walt Disney Company.



A Disney spokeswoman said neither the company nor its chief executive, Robert A. Iger, had received threats. Time Warner declined to comment. The file that was posted regarding Mr. Redstone has details about his family, home and career but does not include private contact information. A Viacom spokeswoman declined to comment.

Anonymous, a loosely organized collective of so-called hacktivists, has called its effort “Operation Hiroshima.” It began on Jan. 1, when the group dropped a trove of documents on Web sites that facilitate anonymous publishing, like Pastebin.com and Scribd.com. The documents included information about media executives and government figures like Mayor Michael R. Bloomberg and New York City Police Commissioner Raymond W. Kelly, and data on corporations and government entities that the group opposes.

“They should feel threatened,” said Barrett Brown, a Dallas-based online activist who has worked with Anonymous, referring to backers of the antipiracy legislation. “The idea is to put pressure on the politicians and companies supporting it.”

The online effort underscores how heated the arguments have become over legislation that may seem like arcane government regulation. Media companies say the legislation, which has bipartisan support, will crack down on illicit downloads of movies, music and television, especially from overseas Web sites. SOPA would expand the ability of the government and private companies to hold Web sites responsible for content the companies believe infringes on their copyrights, allowing greater use of court orders and lawsuits that could ultimately shut down the sites.

The technology industry, including giants like Google and Yahoo, and advocates for Internet freedom say the bills would censor the Internet, stifle free speech and give the government too much power to regulate and shut down Web sites in the United States. Both sides have spent millions on lobbying in Washington. But at the grass-roots level, the issue has galvanized Internet activists, who lack lobbying power but have promoted the cause among the online community.

“You take our speech, you take our Internet, you take our Bill of Rights, you take our Constitution, we fight back,” said a monotone voice on a YouTube video posted by Anonymous before the Operation Hiroshima document drop.

Lawmakers and their aides have also been targets. A photograph of a 25-year-old aide for the House Judiciary Committee was superimposed into pornography by a group related to Anonymous, according to another aide who was briefed on security threats to lawmakers and their staffs. “Why can’t they just hire a lobbyist like everyone else?” this aide said.

The vast majority of SOPA opponents convey their views through legitimate means. Hundreds of Web sites have encouraged blackouts and boycotts to protest the legislation. According to BlackoutSOPA.org, nearly 12,000 users have changed their Twitter profile pictures to a “Stop SOPA” badge.

“The more outrage expressed on the Internet in the coming days, the better,” said Fred Wilson, a managing partner at Union Square Ventures, a venture capital firm and an early investor in Twitter. He said he did not condone threats or “any kind of intimidation” by hackers.

Last month Scribd.com introduced a function that made the words on documents gradually fade away. As they did, a pop-up prompted users to contact their representatives. “Don’t let the Internet vanish before your eyes,” it read.

The tactics have succeeded in some cases. Initially a supporter, the Web hosting company Go Daddy reversed its position on SOPA after Wikipedia and thousands of other Web sites said they would withdraw their domains from the service. “Go Daddy will support it when and if the Internet community supports it,” Warren Adelman, Go Daddy’s chief executive, said in a statement.

Companies like Time Warner, which owns HBO, CNN and the Warner Brothers studio, and Viacom, which owns MTV and the Paramount studio, have experienced security teams, but they are not necessarily trained to handle anonymous online threats, said Josh Shaul, chief technology officer at Application Security Inc., a New York-based provider of database security software.

“It’s easy to get something taken off a Web site, but it’s impossible to erase things off the Internet,” he said.

Less than a week after the Operation Hiroshima documents were posted, a Twitter message linking to Mr. Bewkes’s home phone numbers and addresses, his annual income and his wife’s name and age had spread across the Internet. The message included #OpHiroshima, the shortened Twitter code for the effort.

The global activists in the nebulous collection known as Anonymous often use computer skills to support political causes. For example, Anonymous demanded a full Christmas dinner for Pfc. Bradley Manning, the former Army intelligence analyst who is in prison facing charges of leaking classified documents to WikiLeaks.

Last month, hackers associated with Anonymous published a trove of e-mail addresses and the personal information of subscribers of Stratfor, a security group based in Austin, Tex. Last year, a splinter group affiliated with Anonymous attacked the Sony Corporation, shutting down its PlayStation online network. The attack cost the company around $171 million, according to industry estimates. Movements like Anonymous often squabble among themselves, but SOPA is a uniquely unifying cause, said Gabriella Coleman, a professor at McGill University and an expert on hacking. To these activists, she said, “Internet freedom is not controversial.”