Creating suspended processes

One technique malware uses on Windows to disguise itself is called process replacement or process hollowing. This allows malware to start a well known piece of software like svchost.exe in a suspended state, write malicious code into the processes memory and then start the process running. Anyone looking through running processes will simply see a normal svchost.exe process running. This has the additional benefit of allowing the malicious code to run with the same privileges as the process it is replacing. You can find a lot of examples of how to create a suspended process on Windows but there doesn’t seem to be as many good examples for other platforms. This post will look at Windows, Linux and macOS and how you can create a suspended process on all three operating systems.

5 min read

Building XNU 4903.221.2

Apple finally releassed the XNU source code for macOS Mojave. Oddly enough though it’s the source for 10.14.1 with the source for 10.14 still listed as coming soon. Overall the process remains almost identical to building High Sierra. The one signifigant change I noticed was when executing xcodebuild commands, I needed to pass the -UseModernBuildSystem=NO flag in to get things working properly.

~1 min read

Game Boy boot sequence

The Nintendo Game Boy was first released in North America on April 21, 1989. It wasn’t the most powerful handheld of the time but certainly was the most popular. Over the years I’ve done some reverse engineering on Game Boy Advance and Nintendo DS handhelds but have never looked at the Game Boy. I thought it might be interesting to take a closer look into the boot ROM of the Game Boy and what it does at start up.

2 min read

Virus scanning on macOS

Inspired by a recent post on the MDSec blog, I wanted to take a deeper look at virus scanning on macOS. When I ran into issues getting McAfee kexts approved and loaded correctly it gave me a good excuse to dig deeper. In this post I will provide a brief overview of the different Kernel APIs available to virus scanning tools on macOS and specifically how McAffee’s implementation works. Finally I will cover some things that I think could be improved in the McAfee implementation.

21 min read