1. Cross-Site Request Forgery(CSRF) Attack Lab Zutao Zhu 11/10/2009

2. Outline • Basic idea

3. Basic Idea • 1. The victim user logs into the trusted site using his username and password, and thus creates a newsession. • 2. The trusted site stores the session identifier for the session in a cookie in the victim user’s web browser. • 3. The victim user visits a malicious site. • 4. The malicious site’s web page sends a request to the trusted site from the victim user’s browser. • 5. The web browser automatically attaches the session cookie to the malicious request because it istargeted for the trusted site. • 6. The trusted site processes the malicious request forged by the attacker web site.

4. Task 1 • Use GET method • form data is to be encoded into a URL (key-value pairs) • Put everything into the URL • Use LiveHttpHeader to observer how img tags sends a request

5. Task 2 • Use POST method • Build the form by your code • Submit the form by your code • Use LiveHttpHeader to observer how img tags sends a request

6. Task 3 • Use your Task 2 code to attack originalphpbb.com • How phpBB protects? • Use LiveHttpHeader to observe • POST message includes the sid (cookie)

7. Questions?