The suspected mastermind behind software which wiped out millions of pounds from its victims around the world may never be arrested due to Russian extradition laws.
Between 500,000 and 1 million machines worldwide were infected with the malicious software, which derived from the original "Zeus" trojan for stealing financial passwords that emerged in 2006.
Russia does not extradite accused criminals to other countries, so hacker Evgeniy Bogachev may never be charged in a US court.
Top FBI official James Cole said: "We are in contact with (Russia) and we've been having discussions with them about moving forward and about trying to get custody of Mr. Bogachev," but he declined to provide further details.
A small business owner from Birkenhead lost £100,000 "in three minutes" after one his employees unwittingly opened an email infected with the Zeus virus.
Jonathan Kemp, who runs varnish producer AEV Ltd, told Good Morning Britain their accounts manager opened an email claiming to be from HMRC on the same day cooperation tax was due before entering in confidential banking information.
The US has revealed more details about the attack by a band of hackers who implanted viruses on hundreds of thousands of computers around the world, seized customers' bank information and stole more than 100 million dollars (£60m) from businesses and consumers.
In one scheme, the criminals infected computers with malicious software that captured bank account numbers and passwords, then used that information to secretly divert millions from victims' bank accounts to themselves.
In another, they locked hacking victims out of their own computers, secretly encrypted personal files on the machines and returned control to the users only when ransom payments of several hundred dollars were made.
A Russian man charged by the US authorities with running a hacking gang behind the new powerful malware GameOver Zeus has admitted to writing the software in online forums, FBI documents revealed.
Evgeniy Bogachev told his associates that he had written the credential-stealing software Zeus while chatting to them online, FBI said.
Around 1 million computers globally have already been infected by the new malware, FBI said.
Roughly 25% of the computers are located in the US, with around 15,500 hit in the UK.
The FBI said the malware, known as GameOver Zeus, has helped hackers wipe out hundreds of millions of dollars from accounts around the world.
More than a million computers around the world have been hit by a powerful malware designed to infect computers and mine them for valuable information.
The FBI said users should check for the following symptoms if they fear their computers could have been attacked by the GameOver Zeus malware:
- Computer system operates very slowly
- Cursor moves erratically with no input
- Unauthorized logins to bank accounts or unauthorized money transfers
- Text-based chat windows appear on a computer’s desktop unexpectedly
- Computer files lock up and a ransom demand is made to unlock files
Around 15,500 computers in the UK have been hit, the National Crime Agency said.
The FBI has pressed charges against a Russian man who they believe is behind the malicious software which wiped out millions of dollars from its victims around the world.
The alleged administrator is Evgeniy Bogachev, 30, from Anapa in Russia, who the FBI suspects is leading a tightly knit gang of cyber criminals based in Russia and Ukraine that is responsible for the development and operation of both the GameOver Zeus and Cryptolocker schemes.
The FBI in the US was successful in disrupting a hacking network, making security updates by users around the world more effective, National Crime Agency officials said.
The NCA is working closely with the FBI in order to minimise the impact of the attack.
“Those committing cyber crime impacting the UK are often highly-skilled and operating from abroad,” Andy Archibald from the NCA's National Cyber Crime Unit said.
The design of a new powerful malware makes it "nearly impossible" to completely wipe out, but a coordinated response by the authorities can control it, computer security expert said.
Lamar Bailey, director of security research and development at software company Tripwire, said countries are rolling out a programme to clean up infected computers, asking users to update their security systems.