Mutillidae is a free, open source web application provided to allow security enthusiest to pen-test and hack a web application. Mutillidae can be installed on Linux, Windows XP, and Windows 7 using XAMMP making it easy for users who do not want to install or administrate their own webserver.

Features

Installs easily by dropping project files into the "htdocs" folder of XAMPP.
Switches between secure and insecure mode
Secure and insecure source code for each page stored in the same PHP file for easy comparison
Mutillidae can be installed on Linux, Windows XP, and Windows 7 using XAMMP making it easy for users who do not want to install or administrate their own webserver.
Has dozen of vulnerablities and challenges. Contains at least one vulnearbility for each of the OWASP Top Ten 2007 and 2010
System can be restored to default with single-click of "Setup" button
Used in graduate security courses, in corporate web sec training courses, and as an "assess the assessor" target for vulnerability software
Mutillidae has been tested/attacked with Cenzic Hailstorm ARC, W3AF, SQLMAP, Samurai WTF, Backtrack, HP Web Inspect, Burp-Suite, NetSparker Community Edition, and other tools.

Download
http://sourceforge.net/projects/mutillidae/files/latest/download