New Tests Show Rootkits Still Evade AV

Rootkits are still a security scanner’s worst nightmare: New rootkit detection tests recently conducted by AV-Test.org found that security suites and online Web scanners detected overall only a little more than half of rootkits.

AV-Test.org, an indie security test organization based in Germany, ran two rootkit tests last month, one on Microsoft’s XP Home Edition and another on Microsoft Vista Ultimate Edition, the results of which have been published in a paper now available on the group’s Website.

The XP test used 30 active rootkits and 30 pieces of malware using rootkit technologies. Not surprisingly, anti-rootkit tools did the best, detecting about 80 percent of the rootkits overall, while the security suites found over 66 percent, and online scanners, only 53 percent. Some tools crashed or hung up after completing the rootkit scans, and those were counted as “not detected.”

Security suites did better detecting inactive rootkits than active ones -- most found all (or nearly all) 30. But detecting and cleaning up active rootkits -- which is the task that AV-Test.org considers the “real rootkit test” -- was another story.

Avira AntiVir Premium Security Suite 7.06.00.168 and BitDefender’s Internet Security Suite 2008 11.0.13 led the pack in overall detection of both inactive and active rootkits: Avira’s tool found 28 inactive rootkits and 29 active ones, and all 30 pieces of the malware hidden by rootkits. BitDefender’s tool found all 30 inactive rootkits, 28 of the active ones, and 29 pieces of malware hidden by rootkits.

But Avira had its struggles in removing active rootkits and malware being hidden by rootkits -- it was only able to clean up seven in each case, while BitDefender got successful cleanups in 23 and 27, respectively. Kaspersky Internet Security Suite 7.0.0.119 fared better than most, detecting 24 active and 28 rootkit-hidden samples, and cleaned up 25 of 30 inactive rootkits, 22 active ones, and 25 rootkit-hidden malware samples.

Web-based security online scanners overall struggled to remove rootkits, with an overall 32 percent success rate. BitDefender’s Online Scanner 1.0 Build 2422, for instance, found all 30 inactive rootkits and cleaned up 27 of them, but didn’t do as well as its host-based cousin in detecting and cleaning up active rootkits: It found only five active rootkits and three pieces of malware hidden by rootkits, and could only clean up two of five active ones and none of the three rootkit-hidden malware samples it found.

F-Secure Online Virus Scanner 3.2 Beta (1.0.64) and Panda Security ActiveScan 5.54.01 fared better than other online scanners overall. F-Secure cleaned up 23 active rootkits and 23 samples of malware hidden by rootkits, and Panda, 15 and 26, respectively.

Specialized anti-rootkit tools for the most part performed well in the XP tests, with only a handful that struggled, including Microsoft’s Rootkit Revealer 1.71.0.0, which found only 15 active rootkits and 14 malware samples hidden by rootkits. Safe'n'Sec Pro 3.0.0.4104 and System Virginity Verifier 2.3 had trouble cleaning up rootkits.

The Vista test, meanwhile, used only antivirus tools that had been updated or frozen as of Oct. 2 of last year. And there were problems. “To our surprise, the detection rate of inactive samples reached just 90% on average, even though most of the rootkits used were released during 2005 and 2006,” AV-Test.org researchers wrote.

On average, four of the six rootkits in the test were detected by the AV tools, and only 54 percent could clean them out of the infected machines. AVG’s AntiMalware 7.5.488 couldn’t detect or clean any active rootkits running on Vista, although AVG’s Anti-Rootkit Free 1.1.0.42 tool detected and removed nearly all rootkits in the XP test.

Microsoft Windows Live OneCare 1.6.2111.32 found five of the six total inactive rootkits on the Vista platform, but only one of the six active ones, which it was able to remove successfully. McAfee VirusScan 2008 11.2.121 found six of the inactive ones, and only two of the active ones, which it was able to remove. Some lesser-known AV tools fared more poorly, including Dr Web Antivirus für Windows 4.44.0.09170 and ClamWin Free Antivirus 0.91.2.

Three AV tools had perfect scores, catching all active and inactive rootkits as well as removing all of them: Norton Antivirus 2008 15.0.0.58; Panda Security Antivirus 2008 3.00.00; and F-Secure Anti-Virus 2008 6.80.2610.0.

But with the exception of a few products, most security tools still fall short when it comes to detecting and removing active rootkit infections, according to AV-Test.org. “Without proper anti-rootkit features a protection program may give the user the wrong impression about the status of his PC,” the researchers wrote.

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