Researchers with Microsoft have spotted a spike in Crowti, a ransomware similar to Cryptolocker that encrypts files on victims' machines and then asks for payment to unlock them.
The malware has existed for several months but it wasn't until mid-October that Microsoft's Malware Protection Center noticed its biggest swell to date. The campaign infected 4000 different systems at its peak, with the bulk of those, 71 percent, confined to machines in the United States. [Screenshot]
Similar to CryptoWall, a fairly recent Cryptolocker variant, Crowti uses a valid digital signature to appear legitimate and then, once installed, demands users pay in Bitcoin to purportedly decrypt their files.
Continued : http://threatpost.com/microsoft-warns-of-crowti-ransomware/109075

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