Avast, me hearties! Here there be malware.

Source: http://www.microsoft.com/security/portal/

The Article below is about the Keygen.

One of our most often reported detections in our telemetry each month is the rather innocuously named HackTool:Win32/Keygen. Last month, for example, we received reports of this detection from over 2 million computers. Win32/Keygen is the name we give to programs that purport to activate software without an appropriate license. These programs claim to be able to do things like:

• Generate serial numbers or license keys
• Patch programs in order to bypass activation checks

Basically, these programs exist to enable software piracy. Software piracy is of itself a serious issue, and you can read more about it hereand here. However, according to our telemetry, it seems that using pirated software might have undesired consequences, and of the 2 million computers that reported a Win32/Keygen detection last month, just under 50 percent of these computers also reported at least one other malware infection. It is also worth noting that some of the most dangerous and difficult to recover from malware is commonly distributed masquerading as a keygen.

There are a number of reasons as to why we might see this kind of pattern, but the key takeaway here is that there may be a serious hidden cost to getting software for free. Arrrr...