Today, July 9, is the day when hundreds of thousands of computers worldwide could suddenly lose access to the internet.

It’s when the FBI will shut down some DNS servers it set up last year as a protective measure against a group of people who had created malware called DNSChanger that spread via an online advertising scam to take control of infected computers.

This malware modifies DNS settings to use malicious servers that point users to fake websites and other harmful locations. DNSChanger attempts to modify the settings on home routers as well, meaning other computers and mobile devices may also be affected.

The malicious DNS servers would give fake answers, altering user searches, and promoting fake and dangerous products. Because every web search starts with DNS, the malware shows users an altered version of the internet.

So if your computer is infected with this malware, you’ll likely be offline once the FBI pulls the switch today.

How will you know if your computer is affected? Well, the obvious way is if you suddenly can’t get online. Of course, that can be for many reasons: network down, power outage, etc.

You can find out whether your computer is infected by a simple check at this website run by The DNS Changer Working Group (DCWG):

http://www.dns-ok.us/

Check the DCWG list for websites offering this in languages other than English.

If the resulting page is green, you’re in the clear. If it’s red, your computer may be infected. DCWG offers advice on how can you fix, remove, and recover from a DNSChanger violation.

Stay safe – and connected.

Related reading:

• DNS Changer Malware (PDF) – explanatory document from the FBI.
• Notifying users affected by the DNSChanger malware – news from Google in May 2012.
• Facebook warns users of the end of the Internet via DNSChanger – CNET News report in June 2012.
• Thousands face internet loss as FBI shuts off servers.- BBC News report today.

Related post:

• How to protect your blog from viruses, backdoor Trojans and other nasty stuff