Google Spreads Word On DNSChanger Malware

"Your computer appears to be infected."

Google began displaying that message Tuesday to anyone using one of its search engine sites with a PC that appears to be infected with the DNSChanger malware.

"After successfully alerting a million users last summer to a different type of malware, we've replicated this method and have started showing warnings via a special message that will appear at the top of the Google search results page for users with affected devices," said Google security engineer Damian Menscher in a blog post. The previous effort targeted a fake antivirus software campaign.

[ Read about some real-world examples of mobile malware and the challenges of thwarting them. See 6 Findings That Prove Mobile Malware's Mettle. ]

"Our goal with this notification is to raise awareness of DNSChanger among affected users," Menscher said. Furthermore, since about half of infected PCs appear to be located in non-English-speaking countries, "we believe directly messaging affected users on a trusted site and in their preferred language will produce the best possible results."

Why the proactivity with respect to this particular piece of malware? Because any PC infected by DNSChanger stands to lose Internet access on July 9, 2012. That's the court-ordered date for the FBI and the Internet Systems Consortium to disconnect the domain name system (DNS) servers they're currently using to resolve Internet addresses for PCs infected by DNSChanger. The FBI commissioned the servers after "Operation Ghost Click," in which the bureau and Estonian police worked together to bust six Estonians for using the malware to conduct a four-year click fraud campaign that raked in an estimated $14 million.

To perpetrate the click fraud--forcing a Web browser to "click" on certain advertisements, thus generating revenue from pay-per-impression advertising networks or referral fees--the criminals used their malware to alter the DNS settings on infected PCs to their own rogue DNS servers. Even after the botnet operators were arrested, however, the infected PCs were still relying on the rogue DNS servers to resolve domain names into IP addresses.

For anyone left with a PC infected by DNSChanger come July 9, when the temporary DNS server gets disconnected, the resulting loss of connectivity may not be easy to diagnose. "In the simplest terms, connectivity will not be severed for DNSChanger-infected systems, but Internet communications will not function for infected systems that have not been cleaned up," explained Kurt Baumgartner, senior security researcher for the global research and analysis team at Kaspersky Lab, via Threatpost. "In the U.S., government agencies, home users, and other organizations still infected with the malware will have systems that effectively can't get online, can't send email, etc. It will look like they are connected to their network, but they just won't communicate with anything."

Google's outreach effort alone, of course, won't solve this malware-infection problem. "While we expect to notify over 500,000 users within a week, we realize we won't reach every affected user," said Menscher. Still, reducing the number of infections by any amount will help. "If more devices are cleaned and steps are taken to better secure the machines against further abuse, the notification effort will be well worth it," he said.

Since the botnet takedown, numerous service providers--including AT&T, Bell Canada, CenturyLink, Comcast, COX, Time Warner, and Verizon--have also begun notifying customers whose PCs that appear to be infected. Meanwhile, for anyone else who suspects their PC may have been infected, the DNSChanger Working Group (DCWG) also maintains a list of websites that will identify if your PC is carrying the malware.

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