khast3x / flaskbomb

GZip HTTP Bombing in Python for everyone

Abstract

• Using the famous zip bomb concept (Silicon Valley S3E07), we can send a compressed web-page to the client.
• The browser will unzip the small compressed page into a very big file, potentially crashing it.
• This aims to disrupt or crash bots that scan websites to find vulnerabilities.

tldr - Python GZIP-Bomb HTTP Server

GZip HTTP Bombing in Python for everyone.

Uses Python Flask framework

Docker friendly

It even has it's own low effort logo.

Please keep in mind this is a counter-measure.

Based on this excellent piece by Christian Haschek

Flask Bomb

This repository contains the necessary files to:

• Host a quick & dirty Flask web server that responds to web requests with a GZip archive as a response page.

• The recommended way to use FlaskBomb is by deploying it with Docker. You can try it here:
  

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Features:

• Quick and easy
• Fast deployment using Docker
• Lightweight Alpine based Docker container
• Generic code
  • Implement your own rules or payloads !
• (next)User-Agent evasion based on original work
• Choose classic payload generation or faster append generation method

Usage:

docker run -it -p 80:5000 khanon/flaskbomb <normal|fast> <X> # X is the final payload's size in GB  
# Example:  
docker run -it -p 80:5000 khanon/flaskbomb fast 20

Default deployment sets options to normal 1

Demo - 20G Payloads

Standard docker build from git, demo with cURL

Standard deploy from docker hub, demo with Nikto

Details & Notes

• Gzip's algorithm enables the possibility to append archives
  • normal method generates the payload in one single dd command
  • fast method generates a 1GB payload and appends itself n times. The final payload is bigger but generates much faster.
• Python 3
• Since this uses Flask's built-in web server, internal port is 5000
• The payload is generated using gzip and dd on Docker entrypoint.
  • *NIX based for now
  • Full python payload is up for next release
• Flask development server is used. It is recommended to deploy the application on a WGSI + HTTPD
• For those not using docker, generate the payload using the bash commands in entrypoint.sh and save it as ./static/cake.gzip
  • The python GZip implementation should make this easier in the future

Roadmap

• Evasion
• Python gzip implementation
• Load evasion URIs from DirBuster
• Fingerprinting JS before payload delivery