Posted by Calico UK - 15:55 on 17 May 2012
If you wake up on the morning of July 9th and find that your PC can't surf the Internet, it could be because it's been infected with the DNSChanger Trojan.
PCs use DNS services to convert from computer and website names (eg www.bbc.co.uk) into the numerical address of the host computer (eg 220.127.116.11). Without this service you can't surf the Internet. Your PC will normally be configured to get this DNS service from your broadband provider. But if your PC was infected with the DNSChanger Trojan, your PCs settings will have been changed and it will instead be getting its DNS services from rogue servers run by cyber-crooks. By changing your settings in this way, they can steer you towards websites and servers of their choice rather than the website you wanted, and possible steal your personal details and secrets on the way.
In November the FBI broke the command and control infrastructure driving this virus. But since around 300,000 computers had the infection, temporary legitimate DNS servers were installed in place of the rogue DNS servers to prevent users losing access to the Internet. These replacement servers are due to be switched off on July 9th. After that date, if your PC is infected, it won't be able to find its way around the Internet.
Security company Avira has a tool that allows you to check your DNS settings of your PC to see if its infected. See http://techblog.avira.com/2012/01/23/avira-dns-repair-tool-released/en
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