CTF

CTF Write-Ups

picoCTF2019 Reverse Engineering Asm

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Hello, here’s my take on the picoCTF2019 reverse engineering asm challenges. If you don’t know assembly, please watch a few tutorials on it: http://opensecuritytraining.info/IntroX86.html http://opensecuritytraining.info/IntermediateX86.html asm1 – Points: 200 CMP: Compares the first source operand with the second source operand and sets the status flags in the EFLAGS register according to the results. The comparison is performed by subtracting the … Read more

PicoCTF 2019: whats-the-difference (Points 200)

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Can you spot the difference? kitters cattos. They are also available at /problems/whats-the-difference… on the shell server In order to easily solve this challenge, I’ve used xxd and cut to generate an ascii hexdump of the images: Since I wanted to do a per character diff I wrote the following Python script: And finally run the script:

X-MAS CTF 2019: Binary Exploiting & Reversing Write-Ups

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Hello, Here are my write-ups for the X-MAS CTF 2019 organized by https://htsp.ro/. Reversing: Santa’s crackme Santa’s crackme is easy to solve when using Ghidra, all you need to do is open up the binary, read the code and use the XOR Memory script from Ghidra. Reversing: X-MAS: Lapland Mission Since this is an Unity game we can easily patch … Read more

Hack The Box – Bitlab

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Hello, Here’s how I’ve solved the Bitlab machine on Hack The Box. Gitlab Access As usual we start of with a nmap scan: The scan shows an nginx web server and ssh. If we visit the web server we’ll find a Gitlab instance. Gitlab is used by developers to host their source code. I tried searching for exploits but nothing … Read more

Hack The Box – Travexec Write-up

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Hello, Here’s my write-up for the Traverxec machine. Initial Shell: google User Hint: Read the configuration carefully and `ls` dem directories, and don’t forget, you’re the web server! Root Hint: In linux you can configure commands to be executed without requiring a password. The password for the PDF is the root flag. Link: BananaPr1nc3-Traverxec.pdf

HackTheBox Reversing DSYM Write-Up

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Hello, Here’s my write-up for the Reversing DSYM challenge from HackTheBox. PDF: https://1drv.ms/b/s!ApWG8dlpzmQV-F7NJOZ2GJ0-f0ZJ The password for the Write-Up is the challenge’s flag. To solve it I’ve used: https://ghidra-sre.org/ https://gchq.github.io/CyberChef/ Write a comment if you need a hint or something is not clear. Thanks for reading!

Root-Me: GB – Basic GameBoy crackme walkthrough

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Hello, In this article I will describe how I solved the GB – Basic GameBoy crackme challenge from Root-Me. Before reading this article you should attempt to solve the challenge on your own. Start by reading/skimming through the GameBoy CPU manual then download an emulator such as mGba and play with the ROM. To disassemble the ROM I’ve used Ghidra and mgbdis. After reading through the GameBoy … Read more

Root Me – Xor Madness – Walkthrough

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Hello, In this article I will describe how I solved the PE x86 – Xor Madness challenge from Root-Me This challenge will ask you for a password and the password is also used to validate the flag. What makes this challenge interesting is that it only uses xor, sub, call and ret. Here’s how I approached the challenge: Since the binary had a few function and some strings … Read more