This is Part 3 of the rootkits primer created by
Corey from WatchGuard. Begin by
watching Part 1, if you have not done so already. In this video Corey talks about kernel mode rootkits. He begins the discussion with the basics of user mode and kernel mode, and talks about Ring 0 to Ring 3. Ring 0 has the highest privilege and is generally the kernel code of the system. Ring 3 has the least privilege and this is where all the userland programs operate. The operating system ensures that a lower privilege process, cannot read or write to the memory of a higher privilege process. As an example, a userland program such as a word processor cannot read / write to the windows kernel memory. This mechanism ensures that the system remains uncorrupted even if userland programs malfunction. Most Anti-Virus and Firewalls work in kernel mode, so that they can continuously monitor userland programs for malicious activity. Thus all userland rootkits can easily be detected by kernel mode AV tools. But what if the rootkit itself was in kernel mode? Enter the world of kernel mode rootkits! A kernel mode rootkit runs in Ring 0 and thus has the highest privilege . Such a rootkit is very tough to detect as it can easily subvert AV mechanisms and is even tougher to remove from an infected system.
In this video Corey explains how kernel mode rootkits work at a very high level and talks about rootkit detection software such as
Rootkit Revealer,
BlackLight and
IceSword. Note that we also covered the
Helios Lite Rootkit Remover from
Miel E-Security a couple of videos back. Enjoy!