There may be no emails or lolcats later for more than 300 000 people as the FBI shuts off servers used by cyber criminals. The FBI seized the servers in November 2011 during raids to break up a gang of criminals who used viruses to infect more than four million victims.

Victims’ web searches were routed through the servers so they saw adverts that led to the gang being paid. The gang racked up more than $14 million (R115 million) by hijacking web searches and forcing victims to see certain adverts. They managed to do this because their servers were taking over a key web function known as domain name look-up. The BBC explains:

Domain names are the words humans use, such as bbc.co.uk, for websites. These are converted into the numerical values that computers use by consulting domain name servers (DNS). When a person types a name into a browser address bar, often their computer will consult a DNS server to find out where that website resides online. The gang infected computers with malware called DNS Changer because it altered where a PC went to convert domain names to numbers.

Machines from all over the world still have the gang’s malicious code running. The FBI is said to be shutting off the servers at around 18h00 South African time. Since the FBI raids, the gang’s servers have been run by Californian company ISC. The original population of four million infected machines has been worked  down to just over 300 000, according to statistics gathered by the DNS Changer Working Group.

The largest group of machines still harbouring the infection are in the US but many other nations, including Italy, India, the UK and Germany, have substantial numbers still checking in with the ISC servers. Click HERE to check if you are infected.