CTFs-writeups

Writeups for various CTFs competitions

Tools for CTF

Here is a list to various useful tools for CTF competitions.

Network

• Wireshark to analyze network connections

Web

• Postman to make HTTP requests
• OWASP ZAP for analysing website security. Features include requests analysis and forgery, fuzzing, etc...
• sqlmap for automatic SQL injection

Reverse engineering

• Ghidra to decompile c code.
• Java decompiler
• gdb a C debugger
• OllyDbg a debugger for Windows programs
• Android studio to edit and analyse APK files and emulate APK
• Apktool for reversing APK files
• angr for symbolic execution. See writeup.

PWN

• pwntools a Python library for PWN
• ROPGadget search for gadget and ROP chain generation
• lib search database for ret2lib. See also writeup 32 bits and writeup 64 bits.

Steganography

• file to determine file type
• strings to print all ASCII strings in file
• binwalk to find embedded files
• StegSolve an image solver
• Steg online for images
• Morse decoder
• MMSSTV for HAM transmissions
• Digital Invisible Ink Toolkit for images
• DeepSound for sound files
• Raw Pixels an online RAW image viewer
• Hexed.it to edit the bytes of a file

Forensics

• Autopsy for device analysis

Cryptography

• https://www.dcode.fr/en It knows a lot of common cypher methods and does automatic uncyphering
• hlextend a Python library for length extension attacks on Merkle-Damgård hash functions
• Factorize big integers with http://factordb.com/

Password cracking

• JohntheRipper

OSINT

• Sherlock to scrap information on social media

Misc

• If you know the format of the flag, you can use flag_converter.py to quickly have the most common encoding of the flag, so you know what to look for during the competition ;)
• https://www.asciitohex.com/ For quick conversion between ASCII, decimal, base64, binary, hexadecimal and URL
• https://gchq.github.io/CyberChef/ Same as asciitohex but more complete, with magic wand.
• https://upload.wikimedia.org/wikipedia/commons/d/dd/ASCII-Table.svg: An Ascci to decimal, hexadecimal, binary and octal table
• Deal with images in Python using PIL. See example writeup

Writeups from other people

This file holds some links to tasks I have failed in the past and whose writeup may be helpful later.

Pwn

• Some task with Python bytecode: Puffer Overflow

Crypto

• Ciphertexts with unknown but classical cipher: Video
• Hill cipher solver: Embrace the Climb

Misc

• Some task with an Arduino compiled binary: A Flash of Inspiration
• Blockchain: Bitcoin transaction vulnerability