Avoid Net Shutdown Related To DNSChanger: SMB Tips

The actual threat behind the DNSChanger malware lost its teeth late last year, but confusion could still reign for plenty of computer users come July 9.

More than 300,000 PCs remain infected, long after the FBI caught the bad guys and took control of the servers behind DNSChanger. That's in spite of public pleas for businesses and other computer users to take steps to ensure they won't suffer an Internet outage when the FBI shuts down the DNSChanger servers July 9. (Since nabbing the bad guys, the agency has been running "clean" servers that have allowed affected machines to connect to the Internet without issues.) Even Google starting pitching in last month, notifying users that appeared to be infected. The efforts haven't been for naught; the number of unique IP addresses communicating with the FBI servers peaked at more than 800,000 last November.

Small and midsize businesses (SMBs) that take a see-no-evil, hear-no-evil approach are vulnerable here because compromised machines require a modicum of manual effort to resolve. Antimalware programs might show the end user an (easily ignored) alert if it finds DNSChanger, but are unlikely to automatically restore the correct DNS settings. Symantec, for example, notes that its "products do not restore the DNS settings on a compromised computer because we have no way of knowing what the original settings were." Restoring DNS settings incorrectly could cause further issues.

[ Take a refresher course in SMB security. Read 5 Flame Security Lessons For SMBs. ]

The downside for SMB users that get knocked offline July 9 isn't particularly ominous, but it's potentially a giant pain in the you-know-what. That's because anyone who gets that far without knowing they're affected is also likely to not understand why they can suddenly no longer connect to the Internet.

"The business won't end, it won't implode, but there will be a significant cost as they try to figure this out," said Kevin Haley, director of Symantec Security Response, in an interview. "They'll go through a lot of different troubleshooting steps not realizing what the real issue is. There will be a lot of time wasted." Money might go down the drain, too, particularly at any SMB that calls in an outside IT consultant to help figure out why they suddenly can't get online.

There's plenty of good news, though. For starters, it's very easy to find out if your PC is among the machines that will lose Internet access July 9--just click here. If you're unaffected, you're done. That's it. If you are among the infected machines, the fix is relatively simple. You just need to restore your original DNS settings. (If that sounds like Greek, contact your Internet service provider or IT administrator to learn how to do so.) The DNSChanger Working Group has posted general instructions for fixing affected machines, too.

Don't expect an extension on the FBI's July 9 shutdown. Haley said the agency has done all it can to get the word out and that continuing to keep the servers up and running--which costs money, among other considerations--no longer make sense. It's time to pull the plug.

"They can't just keep doing it forever," Haley said. "At this point, I think if people don't become aware of it, they're never going to become aware of it. [Shutting down the servers] is probably the only thing that can be done at this point."

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