Another government safety net is going away July 9. But this one has nothing to do with food stamps, welfare or Medicaid. These are safety net servers put in place last Nov. 8 after the FBI's "Operation Ghost Click" shut down a hacker group operating under the company name "Rove Digital," which had been running an Internet ad scam since 2007 using DNSChanger servers that hijacked about four million computers worldwide and at least 568,000 in the U.S. The hackers made at least $14 million from the scam, and made the infected computers reliant on the rogue servers for their Internet browsing. According to the FBI, if the agency had simply taken down the criminal infrastructure and confiscated the rogue servers, the victims would have been unable to get Internet service. So on the night of the raid, which led to the arrest of six Estonians, Paul Vixie, founder and chairman of Internet Systems Consortium, was hired to install two "clean" servers that took the place of the impounded ones. Those servers were scheduled to shut down March 8, but a federal judge extended the deadline to July 9. FBI spokeswoman Jenny Shearer says the agency has been making efforts to reach those still infected by the scam, to point them to the website of the DNS Changer Working Group (DCWG), which offers detection, a fix and protection. But security experts say it is well worth it for users to have their computers checked by someone with technical expertise. "It may even be necessary to have it restored to its original settings," Shearer says. "Once you have one thing, you often have many more," says Dan Philpott, a federal information security architect from the Washington, D.C. area. Indeed, according to the FBI, the hackers took advantage of vulnerabilities in the Microsoft Windows operating system to install malware on victim computers that turned off antivirus updates and reprogrammed them to use rogue DNS servers in data centers in Estonia, New York and Chicago, owned by the attackers. The computers could then be directed to fraudulent versions of any website, since users would be looking at an altered version of the Internet. And as security engineer Eric Cissorsky noted in a post in February on Infosec Island, "The nature of DNSChanger was to redirect infected systems to malicious destinations. Many of these sites in turn installed additional malware & Trojan horse malware such as Zlob, TDSS, Alureon, TidServ, and TLD4 will most likely be present on DNSChanger infected systems." In an interview this week, Cissorsky says users infected with DNSChanger should use some type of offline anti-virus scanner, such as MS Windows Defender Offline, to detect\/remove any other malware present on the machine." And for those who are not sure if they are infected, he says, "every major vendor offers some type of free online scanner. Several even provide offline scanners free as well. When in doubt scan, scan and scan some more. It's usually a good idea to use more than one vendor as well. The FBI says while the number of infected users has declined, there are still an estimated 85,000 in the U.S. Another extension of the deadline beyond July 9 is not expected. "This was never intended to be a permanent solution," Shearer says.