The UK’s National Crime Agency (NCA) has urged individuals in the country to be vigilant when going online, as a “particularly virulent” type of malware poses a credible threat.

The Dridex malware, which also goes by the name of Bugat and Cridex, has so far allowed cybercriminals to steal millions from bank accounts in the UK (losses estimated at £20 million).

Many victims are unaware that they have been affected by the virus, with the NCA advising online bankers to check their accounts for any unusual behaviour.

Additionally, the agency also recommends that internet users update their operating system, as well as invest in a security solution if they have not already.

It is thought that the Dridex malware, believed to have been developed by attackers based in Eastern Europe, is spread through emails that users reason to be authentic.

Once opened, the virus then infects a computer. From this point, cybercriminals are able to “harvest” online banking details.

It is estimated that thousands of computers in the UK, predominantly Windows-based, have been infected with the malware.

The NSA said that it is working closely with the FBI to tackle this virus. Presently, their strategy is to “sinkhole” Dridex, which will hopefully prevent botnet computers from communicating with cybercriminals.

Their efforts are being supported by Europol, the Metropolitan Police Service, GCHQ, CERT-UK, Germany’s BKA and the Moldovan authorities.

“Cybercriminals often reach across international borders, but this operation demonstrates our determination to shut them down no matter where they are.”

“We urge all internet users to take action and update your operating system,” said Robert Anderson, executive assistant director of the FBI.

“Ensure you have up-to-date security software and think twice before clicking on links or attachments in unsolicited emails.

“Cybercriminals often reach across international borders, but this operation demonstrates our determination to shut them down no matter where they are.”

Last month, the NCA announced that it was pursuing a more global approach in its battle against cybercrime.