It is important to learn the layout of the Linux kernel image if you want to be a true master of kernel forensics in Linux. Attackers can modify the kernel memory to create very sophisticated kernel rootkits. There are quite a number of techniques out there for infecting a kernel at runtime. To list a few, we have the following:
A
sys_call_tableinfectionInterrupt handler patching
Function trampolines
Debug register rootkits
Exception table infection
Kprobe instrumentation
The techniques listed here are the primary methods that are most commonly used by a kernel rootkit, which usually infects the kernel in the form of an LKM (short for Loadable Kernel Module). Getting an understanding of each technique and knowing where each infection resides within the Linux kernel and where to look in the memory are paramount to being able to detect this insidious class of Linux malware. Firstly, however, let's take a step back and see what we have to work with. Currently...