Writeups – CTF Challenge Solutions

Misc 2026-10-09

OverTheWire Bandit Level 4 Writeup — Spot the Real Text File Among Junk

Ten near-identical files, only one holds the password. Using file to spot the real text file among decoys.

Misc 2026-10-08

PicoCTF First Grep Writeup — Find a Flag with grep

Find a flag hidden in a haystack of text with grep.

Misc 2026-10-06

OverTheWire Bandit Level 3 Writeup — Find a Hidden Dotfile

ls shows an empty folder — until you remember dotfiles don't show by default. Uncovering a hidden password file.

Misc 2026-10-05

PicoCTF Wave a Flag Writeup — Read a Remote Binary's Help Output

Learn to read a remote program's help output to get the flag directly.

Misc 2026-10-02

OverTheWire Bandit Level 2 Writeup — Read a Filename With Spaces

A password file with spaces in its name trips up anyone who doesn't quote or escape it properly in the shell.

Pwn 2026-10-01

PicoCTF Buffer Overflow 1 Writeup — Overwrite a Return Address to Call win()

Redirect execution to a win() function by overwriting the return address.

Misc 2026-09-29

OverTheWire Bandit Level 1 Writeup — Read a File Named -

A file literally named - breaks a naive cat command. How to reference it directly and read the password inside.

Pwn 2026-09-28

PicoCTF Buffer Overflow 0 Writeup — Overwrite a Variable to Unlock the Flag

Overwrite a control variable via buffer overflow to unlock the flag.

Misc 2026-09-25

OverTheWire Bandit Level 0 Writeup — Find Your First Password

Connect to OverTheWire's Bandit wargame over SSH and read a plaintext readme file to get your first password. The very first step into the game.

Rev Eng 2026-09-24

PicoCTF Keygenme-py Writeup — Reverse a Python License Key Generator

Analyze a Python key-generation script to produce a valid license.

Rev Eng 2026-09-21

PicoCTF Vault Door 1 Writeup — Reverse a Character-by-Character Password Check

Reconstruct a password from a character-by-character check in Java.

Rev Eng 2026-09-17

PicoCTF Vault Door Training Writeup — Read a Password from Java Source

Read a vault door's Java source code to find the plaintext password.

Forensics 2026-09-14

PicoCTF TFTP Writeup — Recover a File from a Wireshark Capture

Export a file transferred over TFTP from a network capture with Wireshark.

Forensics 2026-09-10

PicoCTF Wireshark Doo Dooo Writeup — Extract a Flag from an HTTP Capture

Extract a flag sent in the clear over an HTTP stream captured with Wireshark.

Crypto 2026-09-07

PicoCTF Easy1 Writeup — Recover an XOR Key with Crib Dragging

Recover an XOR key via crib dragging from the flag's known prefix.

Crypto 2026-09-03

PicoCTF Substitution0 Writeup — Break a Substitution Cipher with Frequency Analysis

Solve a monoalphabetic substitution cipher using frequency analysis.

Crypto 2026-08-31

PicoCTF Mod 26 Writeup — Brute-Force a Caesar Cipher

Brute-force a Caesar cipher across the 26 possible shifts.

Web 2026-08-27

PicoCTF Web Gauntlet Writeup — Bypass a Login SQL Injection Filter

Bypass an overly naive SQL injection filter to get past a login form.

Web 2026-08-24

PicoCTF Insp3ct0r Writeup — Find a Flag Hidden in HTML, JS & CSS

Find a flag hidden in three pieces across the HTML source, a JS file, and a CSS file.

Forensics 2025-05-15 · PicoCTF 2023

PicoCTF Hideme Writeup — Extract a Hidden ZIP with Binwalk

Detect and extract a ZIP file hidden inside a PNG image with binwalk. An introduction to steganography.

Web 2025-05-15 · PicoCTF 2019

PicoCTF Cookies Writeup — Full Walkthrough & Flag

Manipulating HTTP cookies to enumerate hidden values and capture the flag. Technique: IDOR via a sequential cookie.

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