The US Department of Justice and US Federal Bureau of Investigation have obtained a temporary restraining order allowing them to disrupt a computer virus that created an international botnet controlling more than 2.3 million computers as of early 2010.
In an unprecedented move, the temporary restraining order will allow the FBI and the US Marshal for the District of Connecticut to set up servers at the Internet Systems Consortium or other ISPs that would stop infected computers from continuing to spread the Coreflood virus, according to court records.
The order allows the law enforcement agencies to send commands to infected computers that stops the Coreflood virus, the DOJ said.
"Allowing Coreflood to continue running on the infected computers will cause a continuing and substantial injury to the owners and users of the infected computers, exposing them to a loss of privacy and an increased risk of further computer intrusions," said Judge Vanessa Byrant of the US District Court for the District of Connecticut.
The DOJ and FBI have also filed a civil lawsuit and delivered criminal seizure warrants in an effort to stop Coreflood and the botnet it has created, the DOJ said.
This week, the DOJ and FBI seized five servers that controlled Coreflood-infected computers. The agencies also seized 29 domain names used by the Coreflood botnet to communicate with the servers.
In addition, the US Attorney's Office for the District of Connecticut filed a civil complaint against 13 unnamed defendants, alleging that the defendants engaged in wire fraud, bank fraud and illegal interception of electronic communications. The DOJ also obtained search warrants for computer servers across the country, it said.
"Botnets and the cyber criminals who deploy them jeopardise the economic security of the United States and the dependability of the nation's information infrastructure," Shawn Henry, executive assistant director of the FBI's Criminal, Cyber, Response and Services Branch, said.
"These actions to mitigate the threat posed by the Coreflood botnet are the first of their kind in the United States and reflect our commitment to being creative and proactive in making the Internet more secure."
Coreflood records computer keystrokes and other private communications, the DOJ said. Coreflood steals user names, passwords and other private personal and financial information allegedly used by the defendants for a variety of criminal purposes, including stealing funds from the compromised accounts.
In one case described in court documents, criminals used Coreflood to take over an online banking session and cause the transfer of funds to a foreign account.
Law enforcement officials believe that the Coreflood botnet has been operating for nearly a decade, the DOJ said.
The Connecticut criminal complaint said a Michigan real estate company lost more than $115,000 to fraudulent wire transfers because of the Coreflood virus. A South Carolina law firm lost more than $78,000, and a North Carolina investment company lost more than $151,000, the complaint said. A defence contractor in Tennessee lost more than $241,000 due to the botnet, the complaint said.
"The full extent of the financial loss caused by the Coreflood Botnet is not known, due in part to the large number of infected computers and the quantity of stolen data," the complaint said.
The DOJ urged computer users to update their security software and scan their computers for viruses.