Microsoft said last week that a skew toward more exploits on Windows Vista can be attributed to the demise of support for the operating system's first service pack.
Data from the company's newest security intelligence report showed that in the second half of 2011, Vista Service Pack 1 (SP1) was 17% more likely to be infected by malware than Windows XP SP3, the final upgrade to the nearly-11-year-old operating system.
That's counter to the usual trend, which holds that newer editions of Windows are more secure, and thus exploited at a lower rate, than older versions like XP. Some editions of Windows 7, for example, boast an infection rate half that of XP.