The malware numbers game: how many viruses are out there?

By Ed Bott
April 15, 2012, 6:00pm PDT

Summary: How many distinct strains of malware are in circulation today? If you said hundreds of thousands or millions, you’re way off. A close look at numbers from one leading security company helps explain why some big numbers don’t tell the whole story.

How many strains of malware are in circulation right now, for Windows PCs, Android devices, and Macs?

That seems like a straightforward question, but the answer is far from simple. And the number might be a lot lower than you think.

If you check with the leading security companies, you might be tempted to pick an answer in the millions. After all, that’s how many listings you’ll find in the definition files for common antivirus programs. At day’s end on April 12, for example, Symantec published the summary shown below, noting that its latest Virus Definitions file contained 17,702,868 separate signatures.

Oh my. 17.7 million? That certainly sounds like a very big number. But before you get swept away, it’s worth taking a closer look at what it really represents.

Eight days earlier, on April 4, that same Norton/Symantec definition file contained 17,595,922 separate detections. With 106,946 additional definitions in a mere eight days, you’d probably conclude that malware is out of control.

Because the Norton brand name is primarily associated with Windows PCs, you’d probably also assume that all of that activity was aimed at the Windows platform.

And you’d be wrong in both cases.