format-string-exploitation

Identify and exploit printf-style format string vulnerabilities in C programs.

1.6k|204|Updated Apr 7, 2026

Search Tags:#security #exploitation #ctf #payload #format-string #memory-leak #binary

Ready to run

npx skills add https://github.com/yaklang/hack-skills --skill format-string-exploitation

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: format-string-exploitation
Source: https://github.com/yaklang/hack-skills/tree/main/skills/format-string-exploitation
Command: npx skills add https://github.com/yaklang/hack-skills --skill format-string-exploitation

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Format string vulnerabilities allow attackers to read memory, leak addresses, and potentially execute code; this Skill provides a playbook to identify, exploit, and safely reproduce these issues in controlled environments.

Core Features & Use Cases

Address leakage via %p, %s, and positional specifiers to determine PIE/libc/base addresses.
Arbitrary writes using %n/%hn/%hhn to modify memory and redirect control flow.
GOT/relocation table manipulation to pivot to code execution in practice, including 32-bit and 64-bit scenarios.
Guidance on bypassing mitigation like Fortify, RELRO, and ASLR in lab settings.
Real-world use cases: CTF challenges, secure assessment training, and vulnerability research.

Quick Start

Analyze a vulnerable program and generate a working fmtstr payload to leak a libc address.

Frequently Asked Questions about format-string-exploitation

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I exploit a format string vulnerability to leak memory addresses?▼

To exploit format string vulnerabilities for memory leaks, use printf specifiers like %p, %s, and positional arguments to read stack data and determine PIE or libc base addresses in vulnerable C programs.

What is the best way to write memory using format string exploits?▼

The best way to write memory using format string exploits is utilizing %n, %hn, or %hhn specifiers to perform arbitrary writes, which can modify GOT entries and redirect control flow.

Can I use format string exploitation to bypass ASLR and RELRO mitigations?▼

Yes, format string exploitation can bypass ASLR, RELRO, and Fortify mitigations by first leaking runtime addresses to defeat ASLR, then using arbitrary write primitives to overwrite GOT entries despite RELRO protections.

How does format string exploitation differ between 32-bit and 64-bit binaries?▼

Format string exploitation differs between 32-bit and 64-bit architectures primarily in stack layout and address handling, requiring specific techniques to align and pass 64-bit addresses through format specifiers.

Why does my format string payload fail to overwrite the GOT table?▼

A format string payload may fail to overwrite the GOT table due to full RELRO mitigation, misaligned stack offsets, or incorrect 64-bit address handling when attempting the arbitrary write.

Do I need to understand stack layout to solve CTF format string challenges?▼

Yes, solving CTF format string challenges requires a deep understanding of stack layout to correctly position arguments, calculate offsets for positional specifiers, and execute reliable memory reads and writes.