The antivirus model in use today is broken, largely because it's set up to block known malware and has no way of anticipating the nature of the next attack. The weakness of this blacklisting approach showed up in the last year as attackers developed faster, automated ways of launching malware variations that eluded unsuspecting defenses. Now being used is a "whitelisting" approach that acts like a nightclub bouncer working from a guest list. If you're not on the list, you're not getting in.

Successive, low-volume attacks last year struck targeted networks in waves. Each contained a slightly different version of a particular malware. The variants had to be individually identified and blocked, allowing malware writers to stay ahead of signature-based antivirus programs, according to a report by e-mail security vendors Proofpoint and Commtouch Software.

"No heuristic can block all of the variants, and by the time a signature is released, that particular outbreak has ended and several new variants have been released," the report says. "In 2006, the massive-variant viruses turned every hour of an attack into a zero hour."

Whitelisting defines up front the programs allowed to execute inside a corporate network and excludes everything else. It "puts the onus on the admins to know what things should be running in the enterprise," says Dennis Szerszen, marketing and product development VP at SecureWave, a maker of endpoint security software that uses whitelisting. "With whitelisting, there's no such thing as a zero-day attack."

MICROSOFT'S NOD

Microsoft has listed SecureWave's Sanctuary 4 software in the Windows Embedded for Point of Service catalog. This should give SecureWave traction in the retail and hospitality industries, where Windows Embedded for Point of Service is used to build and run software on a variety of devices, including smartphones and ATMs.

Conventional antivirus systems are knowledge-based, so if the system doesn't recognize a piece of code as malware, it won't block it, says William Bell, director of security at CWIE Holding, an Internet service provider. "If you let in a virus or a piece of malware, it can run amok."

CWIE runs Sanctuary 4, which includes application and device control capabilities. This lets Bell control which apps run on the company's PCs and servers, as well as whether users can plug iPods or memory sticks into their computers.

While CWIE still runs antivirus software, the company doesn't use anti-spyware software. Because it's not whitelisted, "spyware can't run on our machines," Bell says.

First National Bank of Bosque County in Texas was able to drop antivirus protection from its desktops once it started using SecureWave's Sanctuary Application Control software; it still uses antivirus at the network gateway. "I don't like the existing antivirus model because it's like sitting around and waiting for the bad guys to shoot you," VP Brent Rickels says.

Whitelisting has its own challenges. A company has to identify all approved apps to ensure that legitimate software isn't blocked. The main argument against whitelisting is that it creates administrative overhead by forcing IT managers to inventory their systems so all approved devices and apps can be added to the lists. The whitelist also must take into account upgrades and patches.

Sanctuary works with automated patching systems like PatchLink and includes a utility tool that automatically updates the list with patches and upgrades once the user creates a baseline list of apps. "There's going to be some administrative overhead in terms of adding clients, applications, and patches," Bell says, "but the benefits are that rogue applications and devices can't run on your network." Maybe that's not such a bad trade-off.