Tuesday, April 3, 2012

Introducing Foundstone Hash Calculator, A Fiddler Extension

By Neelay S Shah.

Over the last few months on web application penetration tests, I've come across scenarios where I would need to create a hash for whatever reason. Unfortunately, Fiddler does not have a built-in hash calculator and I couldn't find an already existing Fiddler extension that would do this. I'm a big fan of Fiddler, but I would have to use another proxy like Paros, Web Scarab or Burp just to calculating a hash. So, I wrote this extension that adds the capability to create hashes (MD5, SHA-1, SHA 256, SHA 384 and SHA 512) from within Fiddler itself.

Downloading the Extension

You can download the extension installer from here:

Installation Notes / Pre-Requisites

The extension has the following pre-requisites:
  • .NET framework version 2 or higher - If you already have a working installation of Fiddler on your machine then you already have .NET framework version 2 or higher installed.
  • Fiddler version or later
The installation does NOT need administrative privileges. The extension installs the appropriate assemblies to the following path -
  • C:\Users\\Documents\Fiddler2\Scripts – Windows 7
  • C:\Documents and Settings\\My Documents\Fiddler2\Scripts – Windows XP, 2003 Server

Once installed, the extension can be un-installed from the standard Windows “Add/Remove Programs” snap-in.

Usage Notes

Once installed, the extension can be invoked by launching Fiddler. The tool menu item “Tools -> Hash Calculator” launches the extension. The following screenshots indicate the same:

Invoking Hash Calculator

Hash Calculator in action


  1. Awesome! This is a much needed extension to Fiddler.

  2. Awesome work Neelay. I am already using your hash calculator. :) Keep up the good work sir.