Hello there!
Welcome to my Blog!
I’m Biplav.
Just a place to share some of my writeups about ctf challenges and other topics that I find interesting.
Thank you!

Elf x64 - Right on Time - THCon CTF - Radare2 Write Mode

Greetings everyone! This writeup is going to be about one of the reversing challenges from THCon CTF 2021. Let’s start!!!! Here, Name of the binary is chall.bin. First, Trying to run the binary without any input prints that we need to provide an argument and exits the program.So, let’s try by passing an argument and here it prints Nope sorry, try again and exits the program. So, I loaded the binary in write mode using radare2 with command:
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Living QR - THCon CTF

This was a steganography challenge from THCon CTF where we were given a qr .gif image. When I tried to view it, multiple QR’s were being loaded in a few milliseconds gap. I solved this challenge using imagemagick and zbarimg. First, I used imagemagick to get all single QR’s from the given .gif, and then ran zbarimg to get characters from each file, and when I put all characters together I got the flag.
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You Can’t C Me - Hackthebox

Greetings everyone! This is one of the easy challenges from Hackthebox. I will explain how we can solve this challenge using radare2. Here, Name of the binary is auth. First, let’s load the binary in debug mode with radare2: $ r2 -d ./auth We can list all available strings using iz command. Also let’s see the information of binary using iI command. We can see that binary is stripped, but other protection mechanisms like canary is turned off.
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