Category: Forensics

In BSidesSF CTF, calc.exe exploits you! (Author writeup of launchcode)

Hey everybody,

In addition to genius, whose writeup I already posted, my other favourite challenge I wrote for BSidesSF CTF was called launchcode. This will be my third and final writeup for BSidesSF CTF for 2019, but you can see all the challenges and solutions on our Github releases page.

This post will be more about how I developed this, since the solution is fairly straight forward once you know how it’s implemented.

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Determine Windows version from offline image

I am not a forensics expert, nor do I play one on TV. I do, however, play one at work from time to time and I own some of the key tools: a magnifying glass and a 10baseT hub. Oh, and a Sherlock Holmes hat – that’s the key. Unfortunately, these weren’t much help when I was handed a pile of drives and was asked to find out which version of Windows they had been running. I wasn’t allowed to boot them, and I couldn’t really find the full answer of how to get the version after a lot of googling, so I figured it out the hard way. Hopefully I can save you guys some time by explaining it in detail.

And if there’s a better way, which I’m sure there is, please let me know. I don’t doubt that I did this the hard way – that’s kinda my thing.

The order of events is, basically:

  • Step 1: Copy the system's registry hive to your analysis system
  • Step 2: Mount the registry hive in regedit.exe
  • Step 3: Navigate to the OS version in regedit.exe
  • Step 4: Unmount the registry hive.

If you know how to do all that, then thanks for reading! Check back Tuesday for a brand new blog posting! I have an interesting blog that combines DNS and cross-site scripting lined up.

Otherwise, keep reading. Or just look at the pictures.

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