DerbyCon 9 – DomainTools CTF – Reversing

Part three of the DerbyCon DomainTools CTF write-ups.  You can find coverage of all the Crypto challenges here and coverage of all the Forensics challenges here.  This finishes up the solutions for every challenge in the CTF, broken up by the same section names that they used.  When possible, I’ll also be creating CyberChef recipes to directly solve each challenge, and linking to them following the solution description.  Let’s get started!

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DerbyCon 9 – DomainTools CTF – Forensics

Part two of the DerbyCon DomainTools CTF write-ups.  You can find yesterday’s coverage of all the Crypto challenges here.  I’ll be contributing solutions for every challenge in the CTF, broken up by the same section names that they used.  When possible, I’ll also be creating CyberChef recipes to directly solve each challenge, and linking to them following the solution description.  Today: the forensics challenges!

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DerbyCon 9 – DomainTools CTF – Crypto

Continuing with write-ups for events from DerbyCon is the DomainTools CTF.  I’ll be contributing solutions for every challenge in the CTF, broken up by the same section names that they used.  When possible, I’ll also be creating CyberChef recipes to directly solve each challenge, and linking to them following the solution description.  First up: the crypto challenges!

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DerbyCon 9 – TrustedSec Challenge Coin Solution

This last weekend was the final DerbyCon.  We’ll #TrevorForget.  It was also an event filled with several quick and fun CTFs… and since I’ve been deficient in posting things lately, I figured I’d catch up by showing how to solve a whole pile of them.  First up: the TrustedSec Challenge Coin!  Attendees could get one of these by just showing up and asking for one, and there was a prize pack being awarded to anyone who could solve it.  I was the fifth to do so, and figured others might want to know how to get to the final message.

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Fixing Firmware File Systems

Here’s the scenario: you’ve downloaded the firmware for a device that you want to explore in more depth, and extracted out the updates.  You dig through them and see that they’re EXT4 systems, and say “jackpot!” while rubbing your hands together in glee.  “A quick mount and I can browse to my heart’s content” you say to yourself… and then you see “wrong fs type, bad option, bad superblock on {DEVICE}, missing codepage or helper program, or other error.”  Let’s get past that. 🙂

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Quick Hit: Base64 PowerShell Exfiltration

Okay, so you’ve landed in a constrained language PowerShell on a remote box, and the local application security policy is stopping you from using all the regular stuff (e.g. netcat, opening network connections, etc)… but you need to exfil a medium amount of binary data.  How would you do that?

The following isn’t perfect, but it’s the solution I used recently… feel free to share better solutions! 🙂

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