1. FORESEC Academy FORESEC Academy Security Essentials (II)

2. FORESEC Academy Agenda  Web communication  Web security protocols  Active content  Cracking web applications  Web application defenses

3. FORESEC Academy Everything You Always Wanted to Know About Web Communications...  Servers and Clients  HTTP and HTML

4. FORESEC Academy Everything You Always Wanted to Know About Web Communications(2)  Stateless Communications  Retrieving Information. GET, HEAD  Sending Information. POST, PUT

5. FORESEC Academy HTML Security  Reading HTML Source

6. FORESEC Academy HTML Security (2)  Hidden Fields  Server Side Includes

7. FORESEC Academy Common Gateway Interface (CGI)  Allows web pages to do something instead of just returning pages  Extends the capabilities of a web server  Creates many exposures on server - Leaking information - Performing unauthorized transactions - Executing unintended programs

8. FORESEC Academy Common Gateway Interface (CGI) (2)  Common Mistakes - Misuse of command interpreters - Bad memory management - Passing unchecked parameters to system

9. FORESEC Academy Cookies  HTTP is “stateless” - no context information  Cookies provide “state” and context  Can only hold information given to the browser by the server  Can only be exchanged with originating server or domain  Beware of cross-site sharing (e.g., DoubleClick)  Can block cookies if desired

10. FORESEC Academy What About Non-Persistent Cookies?  Non-persistent cookies = per-session cookies  Non-persistent cookies are not written to the browser file system - So they can't be edited and are therefore safe from session ID attacks. Right? -Wrongo!!!  Several possible methods - 1) Raw read/write from/to the client-side memory - 2) Adapt Mozilla browser source to edit cookies - 3) Write a Javascript app that lets you view page and edit - 4) Write a proxy that allows for editing of entire session passed back and forth from browser (Achilles)

11. FORESEC Academy SSL  Protocol for encrypting network traffic  Operates at Transport Layer  Operates on port 443  How it works - Client connects to server - Server indicates need for SSL - Client and server exchange crypto keys - Secure session begins  Not a guarantee of security

12. FORESEC Academy Secure Electronic Transactions (SET)  Developed by Visa, MasterCard, Microsoft, Netscape  Specific-purpose protocol  Secures credit and debit card transactions

13. FORESEC Academy Secure Electronic Transactions (SET) (2)  Services provided - Authentication - Confidentiality - Message Integrity - Linkage

14. FORESEC Academy Active Content  Programs that interact in a network environment  Java/ActiveX

15. FORESEC Academy Java and JavaScript  Java - executable code  JavaScript - instructions embedded in HTML  Security Model - Execution in a controlled environment (the “sandbox”) - Local apps have more access than network apps - Byte Code Verifier, Class Loader & Security Manager enforce security