U.S. disrupts major hacking, extortion ring; Russian charged

(Adds FBI declining to comment on Zeus authorship)

By Joseph Menn, Jim Finkle and Aruna Viswanatha

June 2 (Reuters) - A U.S.-led international operation disrupted a crime ring that infected hundreds of thousands of PCs around the globe with malicious software used for stealing banking credentials and extorting computer owners, the Justice Department said on Monday.

Authorities in nearly a dozen countries worked with private security companies to wrest control of the network of infected machines, known by the name of its master software, Gameover Zeus.

Court documents released on Monday said that between 500,000 and 1 million machines worldwide were infected with the malicious software, which was derived from the original "Zeus" trojan for stealing financial passwords that emerged in 2006. Officials charged a Russian man with hacking, fraud and money-laundering, and court documents suggested they suspect he wrote Zeus, one of the most effective pieces of theft software ever found.

In addition to stealing from the online accounts of businesses and consumers, the Gameover Zeus crew installed other malicious programs, including one called Cryptolocker that encrypted files and demanded payments for their release. Cryptolocker alone infected more than 234,000 machines and won $27 million in ransom payments in just its first two months, the Justice Department said.

The two programs together brought the gang more than $100 million, prosecutors said in court documents, including $198,000 in an unauthorized wire transfer from an unnamed Pennsylvania materials company and $750 in ransom from a police department in Massachusetts that had its investigative files encrypted. Other victims included PNC Bank and Capital One Bank , according to court documents.

"These schemes were highly sophisticated and immensely lucrative, and the cyber criminals did not make them easy to reach or disrupt," Leslie Caldwell, who heads the Justice Department's criminal division, told a news conference.

The Gameover Zeus "botnet" - short for robot network - is the largest so far disrupted that relied on a peer-to-peer distribution method, where thousands of computers could reinfect and update each other, said Dell expert Brett Stone-Gross, who assisted the FBI.

"We took control of the bots, so they would only talk with our infrastructure," Stone-Gross said.

A civil suit in Pennsylvania helped authorities get court orders to seize parts of the infected network, and on May 7, Ukrainian authorities seized and copied Gameover Zeus command servers in Kiev and Donetsk, officials said. U.S. and other agents worked from early Friday through the weekend to seize servers around the world, freeing some 300,000 victim computers from the botnet so far.