Is this a hoax, or some kind of Y2K scare tactic? Unfortunately, it's very real for about 65,000 U.S. citizens.
I'll give you the good new first: if you've been running antivirus software for the past couple of years, you're probably fine and won't be affected. All the major antivirus companies have been on top of DNS Changer since it came out a few years back and have either blocked or removed it from any infected computer.
So, what exactly is going on?
Over the past 5 years, some Estonian cybercriminals infected approximately 4 million computers with a virus called "DNS Changer." The FBI (and other International law enforcement agencies) finally caught up with these criminals, arrested them, and seized the infected server farm that was doing all the damage.
Then everything should be fine, right?
Not exactly. The problem is, the FBI had to keep those infected servers running since March. Why? Anyone who has a computer infected with DNS Changer would instantly lose Internet access if these servers were shut down (since the infected computers rely entirely on these malicious servers for Internet access).
The FBI decided to give people a chance to clean up their computers before they pull the plug on these malicious servers this coming Monday (7/9/2012). If for some reason you don't run antivirus software, or are just unsure if you're infected, you may lose Internet access on Monday for several hours.
What exactly does DNS Changer do?
In a nut shell, DNS Changer takes over your computer's DNS and points you towards fake search results populated with malicious websites. Any one of these fake sites will further infect you with trojans or other viruses designed to steal passwords, send you spam, or just steal your money flat out. Nasty business.
For instance, if you were infected with DNS Changer, and you did a search for "Netflix," then clicked one of the fake search results, you would be redirected to a bogus (and dangerous) site called "BudgetMatch" instead.
Or if you clicked a search result for ESPN, you might see fake ads on ESPN's site directing you to a fake timeshare business.
As I mentioned above, if you've been regularly running antivirus or Internet security software on your computer, you're almost certainly safe from losing Internet access this Monday, but we recommend that you at least do a simple test to make sure.
U.S. users can click this link to see if their DNS is working properly (which indicates DNS Changer isn't affecting you): http://www.dns-ok.us/
You should see this if your computer is safe:
For other countries, and more information, you can visit this site: http://www.dcwg.org/detect/
If you do find that you're infected, you should install some antivirus software to try to get rid of DNS Changer. In many cases, however, your computer may be so infected that it might be too late even for that. In that case, you should seek out a professional to diagnose and solve the issue.