[danielki]

Piracy is hardly a "clean install". I wouldn't be surprised if a decent-sized number of the bootleg Windows installs out there are heavily-rootkitted.

I haven't seen any recent statistics, but at one point, 74% of rootkit infections were on pirated copies of Windows XP [0]

[0] http://www.zdnet.com/article/study-rootkits-target-pirated-c...

[knd775]

I think that this may actually be attributed to the lack of working Windows Update on a lot of pirated systems.

[danielki]

Yes and no. There is at least one case that I can remember[0] of pirated software being modified to download and install a virus.

According to Microsoft[1], 32% of pirated Windows 7 copies and activation cracks resulted in some sort of malware infection

Speaking anecdotally, most of the friends and family whose computers I've had to clean up have been running some sort of cracked/pirated software that they'd downloaded or had been given to them by a friend

[0] http://voices.washingtonpost.com/securityfix/2009/05/pirated...

[1] Admittedly, Microsoft has somewhat of a bias, but the number sounds reasonable to me: http://archive.news.softpedia.com/news/32-of-Pirated-Windows...