Indie antivirus testing organization AV-Test.org has released its quarterly comparison test of 28 antivirus products, and the results show that one thing's for sure: Few are good at sniffing out rootkits.

There were no big surprises when it came to how the products performed in standard signature detection, generating false positives, proactive detection, and their response time to malware attacks. "Products which performed well last time did perform well this time, too -- the changes are usually plus or minus three percent or so at the maximum," says Andreas Marx, CEO and managing director for the Germany-based AV-Test.org.

But many of the products didn't perform as well when it came to detecting active rootkits on systems. "Many products still have quite some problems here," Marx says. "Active rootkits are very tricky to detect. Without special detection routines, a scanner might report that a system is clean even if it's indeed infected and might be part of a botnet already."

F-Secure, Panda, Symantec, and Trend Micro were the only AV packages that detected all 12 active rootkits in the test, and AntiVir, Avast, AVG, BitDefender, Dr Web, eTrust-VET, Kaspersky, McAfee, Nod32, and Sophos caught all but one rootkit. Microsoft missed two rootkits.

The worst performers: ClamAV, Command, and K7 Computing, which missed three or more of the 12 rootkits.

Symantec performed well in most categories, with 98 percent or more in successful signature detection and zero false positives, but earned only a "satisfactory" rating for its four- to six-hour response time for widespread malware outbreaks. McAfee had a 90 percent or more success rate in signature detection, zero false positives, and a six- to eight-hour response time for widespread malware outbreaks. Both McAfee and Symantec scored in the "good" range for proactive detection.

Microsoft fared the same as McAfee in signature detection (90 percent or more) and generated no false positives. But Microsoft received a "poor" grade in proactive detection, and a "very poor" in its over eight-hour response time in widespread malware outbreaks.

Meanwhile, the number of MD5-unique malware samples received by AV-Test.org has increased dramatically -- from 972,000 in 2006 to 5,490,000 in 2007. Marx says the good news is that AV vendors are now more frequently updating signatures to keep up with the barrage of new malware.

Those numbers have a lot to do with the increasing number of variants for Trojans and other malware samples, notes Alex Eckelberry, president and CEO of Sunbelt Software. "There are many [samples] that are variants of the same piece of malware," he says.

— Kelly Jackson Higgins, Senior Editor, Dark Reading