At this point, some might suggest that Microsoft products are the primary target for attacks and overall market share has nothing to do with it. The fact is, in every instance where the non-Microsoft product is more popular than the Microsoft product, the non-Microsoft product is attacked more. QuickTime and iTunes is exploited more often than Windows Media Player. Macromedia Flash is attacked more often than Silverlight. Adobe Acrobat's PDF files are attacked more than Microsoft's XPS or DOCX files. Apache Web Server is successfully exploited more than IIS. PHP is exploited more than ASP and ASP.Net. Java is exploited more than .Net. SSH is attacked more than RDP. This all lends further credence to my corollary.
Readers, I invite you to prove me wrong. Send your exceptions to Roger's Hacking Popularity Corollary to firstname.lastname@example.org. Although I'm not sure one or two rare exceptions with very small populations would invalidate all the examples I've shown above, I'm open-minded. Given enough examples, I'm willing to forget my corollary.