Update: Ukranian police arrest 5, targeting brains behind Zeus botnet

IDG News Service -

Ukrainian police on Thursday arrested five people thought to be the brains behind a scam using the Zeus Trojan to siphon money from small businesses in the U.S.

The operation is part of an ongoing effort to take down a criminal empire that stole $70 million from victims' bank accounts over the past few years. Many of those hit were small businesses or local organizations that ended up having to absorb the costs of the fraud.

Ukraine's national police force, the SBU, made the arrests as part of a joint effort with the U.S. Federal Bureau of Investigation, police in the Netherlands and the U.K.'s Metropolitan Police Service. Those detained are "key subjects responsible for this overarching scheme," the FBI said in a statement.

Ukrainian SBU agents also executed eight search warrants in an operation that was manned by about 50 police officers.

Law enforcement officials believe they arrested a "top-tier group" of organizers of the wide-spread operation, FBI officials said at a press conference Friday. The operation used an estimated 3,500 money mules, people who transferred money back to the organizers, FBI officials said.

"We believe we've dismantled the operation" with the recent arrests, said Gordon Snow, assistant director with the FBI's Cyber Division.

The Ukraine arrests are "far more significant" than the earlier actions in the U.K. and the U.S., said Gary Warner, director of research in computer forensics with the University of Alabama at Birmingham. "These are five ringleaders," he said. "All roads lead back to these five guys. The people that were arrested in the UK and the people that were arrested in the U.S... all were piling their money back to these guys in Ukraine."

Zeus is considered to be the most lucrative piece of malware ever created, and it took a network of operatives to manage the operation. On Tuesday, the Metropolitan Police Service in London arrested 20 people, and that was followed up by more arrests in the U.S. on Thursday. Both operations dismantled the "money mule' system used to move funds overseas.

U.S. officials have charged 92 people with crimes related to the operation and arrested 39, the FBI said. The operation targeted small businesses and other organizations in the U.S., with the criminals often focusing on treasurers or chief financial officers of the organizations, the FBI said.

The operation -- named Trident Breach -- was launched in May 2009 after FBI agents in Omaha, Nebraska, began investigating a computer fraud case that involved 46 unauthorized payments made to different bank accounts across the country. This type of fraud is the trademark of the Zeus network. In a typical Zeus theft, the criminals hack into the victim's online bank account and then move money out using the banking system's automated clearing house (ACH) money transfer system.