The FBI is worried that over 350,000 computers might lose access to the Internet on July 9th, all because a Trojan, named DNSChanger, tried to disrupt how Internet-connected computers find each other.
DNSChanger belongs to a category of Internet threats known as "DNS Malware," which by design try to reroute or otherwise manipulate Internet traffic for criminal purposes.
Domain Name System (DNS) is the global directory that allows the use of friendly names as Web addresses. DNSChanger, however, causes infected PCs to query servers that return bogus information, diverting hapless Web surfers to phoney Web sites to be victimized.
The criminals behind the scam were caught, but not before millions of computers were infected. In order to prevent a widespread loss of access to the Internet, the FBI evidently obtained a court order last November authorizing the Internet Systems Consortium (ISC) to deploy and maintain temporary clean DNS servers.
These servers were supposed to be decommissioned in March, 2012, but the deadline was extended because DNS query traffic indicates that many PC are still infected.
Stories like this have a tendency to be sensationalized, but there is no reason to panic. The best course of action is to check your PC to see if it has been affected. A site, called DNS-OK.us, makes the detection process especially easy.
If your PC is a victim of DNSChanger, free removal tools are listed on the DCWG's website, and if you want to help the FBI's investigation of DNS Malware, you can let the agency know you were affected by submitting a report on FBI.gov.
Most up-to-date anti-virus software is DNSChanger-aware, but it doesn't hurt to check on all your PCs. Again, to do so, simply visit DNS-OK.us.