A three-fold increase in Microsoft Windows computers infected with malicious software in late 2013 came from an application that was for some time classified as harmless by security companies.



From Computerworld:

The finding comes as part of Microsoft's latest biannual Security Intelligence Report (SIR), released on Wednesday, which studies security issues encountered by more than 800 million computers using its security tools.

In the third quarter of 2013, an average of 5.8 Windows computers out of every 1,000 were infected with malware, said Tim Rains, director of Microsoft's Trustworthy Computing division, which tracks security trends targeting the company's widely used products. That jumped to about 17 computers per 1,000 for the last quarter of the year.

  Malware infections tripled in late 2013, Microsoft finds