US antivirus vendor Webroot has bought UK-based Prevx in an acquisition that looks like the latest symptom of the growing dissatisfaction among security companies with the current signature-based scanning model for detecting malware.

On the face of it a 20-person software security company based in Derby is an unlikely bride for an ambitious US outfit looking to grow. But since its founding as long ago as 2001, Prevx has been a pioneer of the application fingerprinting technology that in the cloud services era has suddenly become ultra-fashionable.

Webroot will now spend the next six months integrating Prevx’s cloud-oriented application profiling into its own development program. The Derby employees will be retained and the technical effort spread to engineers based in the US and Austria.

Further down the track, it looks as if the Prevx approach will be used to supplement the company’s signature-based scanning antivirus products with a possible view to replacing it entirely when the market is deemed ready.

Application fingerprinting is a very different approach than signature-based detection, and is based on separating the thousands of known good apps from unknown and suspect ones. Any unknown programs encountered are compared to fingerprints in a cloud database to determine whether they are harmful and if they can't be identified at all they are blocked as a precaution.

The advantage is that the PC does not need to keep updating itself with signatures of every piece of malware, a chore for most users. The hard work is done remotely.

“They are a minimum of two to three years ahead of anyone else,” said Webroot CEO, Dick Williams as a rationale for buying Prevx rather than matching its development inhouse.

“Over time signature-based solutions will become inadequate,” he agreed.

Webroot has been on a modest spending spree recently, acquiring California-based BrightCloud and Email Systems Scandinavia (ESS) of Sweden during 2010.

As it builds a service-based presence, including cloud security, Webroot itself could become a takeover target at some point.

After re-developing its software over the years, Prevx has achieved some success in niche markets such as online bank security with products such as SafeOnline.