Kimmo Kasslin from F-Secure has released a paper on Kernel malware. In the paper, a brief overview of kernel malware is provided followed by detailed analysis of the kernel malware and case studies. If you ever wonder how kernel rootkit and other kernel level malware works, this is a good paper to read.

Follow this link to the paper. Together with the paper, Kimmo's slides for AVAR 2006 conference talk on the same topic is also released.