CTF Writeups

Detailed solutions and approaches to various CTF challenges

Binary Exploitation
December 22, 2025

TSGCTF - global-writer

global writer
Summary

This challenge is a global out-of-bounds write.

  • The program lets you repeatedly set values[idx] = v.
  • There is *...
theg1239
cat writeup.md
Difficulty:
Web Exploitation
December 22, 2025

TSGCTF - image-compress-revenge

image-compress-revenge
TL;DR

The server runs ImageMagick through bash -c and tries to escape the uploaded filename. By uploading a file whose filename contains a backslash before $ (`$F

theg1239
cat writeup.md
Difficulty:
Web Exploitation
December 22, 2025

TSGCTF - Mission: Impossible

Mission: Impossible
Summary

The site is a Gradio “CIA Vault Terminal” that transcribes uploaded audio with Whisper. If the transcription contain...

theg1239
cat writeup.md
Difficulty:
Cryptography
December 22, 2025

0CTF - Nightfall Tempest

Nightfall Tempest Trials
Overview

The challenge provides:

  • pk: Kyber public key (K=12)
  • ct, iv: AES-256-CBC ciphertext and IV
  • leaks...
theg1239
cat writeup.md
Difficulty:
Reverse Engineering
December 22, 2025

0CTF - perspective

perspective

Category: reverse / misc
Prompt: “An artist’s perspective is always unique”

TL;DR

The binary is a Windows x64 OpenGL/GL...

theg1239
cat writeup.md
Difficulty:
AI
December 22, 2025

0CTF - ProAgent

ProAgent

TL;DR: The service lets anyone point it at an arbitrary MCP server (POST /config). The agent also exposes an internal read_file tool that can read /flag. By hosting a malicious M

theg1239
cat writeup.md
Difficulty:
Reverse Engineering
December 22, 2025

0CTF - JSHacker1

JSHacker1
Challenge Summary

We are given a bundled V8 d8 binary and an obfuscated JS file. The service asks for a token via `nc instance.pengu...

theg1239
cat writeup.md
Difficulty:
Miscellaneous
December 22, 2025

0CTF - GhostDB

GhostDB - OoCTF Writeup
Challenge Summary

GhostDB is a toy database service written in V. The flag is awarded if a single session performs more ...

theg1239
cat writeup.md
Difficulty:
Binary Exploitation
December 22, 2025

0CTF - chsys

chsys
TL;DR

The service runs a FreeBSD “base system environment manager” binary (env_manager) inside a jail. The binary builds shell commands ...

theg1239
cat writeup.md
Difficulty:
Cryptography
December 22, 2025

0CTF - baby discriminator

baby_discriminator
Challenge Overview

We need to distinguish between two types of random vectors 200 times in a row to get the flag.

  • Bit 1: The vector (length 140) is completely random. Ea
theg1239
cat writeup.md
Difficulty: