The Mocbot worm attacks machines running Windows 2000 or XP that only have Service Pack 1 installed.

BBC: NEWS | Technology | Hackers target latest Windows fix

Why, that would be everyone using Windows XP and 2000 because only IE 8 and lower are supported on those operating systems.

FORBES: Another Reason to Get Rid of Internet Explorer

When the iPlayer first launched the BBC was criticised for producing versions that only worked with Microsoft's Windows XP and which used Microsoft's digital rights management (DRM) system to enforce viewing restrictions.

BBC: iPlayer now available on Mac