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FORE SEC Academy Security Essentials (II ). Web Communications and Security. Agenda. Web communication Web security protocols Active content Cracking web applications Web application defenses. Everything You Always Wanted to Know About Web Communications. Servers and Clients
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FORESEC AcademySecurity Essentials (II) Web Communications and Security
Agenda • Web communication • Web security protocols • Active content • Cracking web applications • Web application defenses
Everything You Always Wanted to Know About Web Communications... • Servers and Clients • HTTP and HTML
Everything You Always Wanted to Know About Web Communications(2) • Stateless Communications • Retrieving Information . GET, HEAD • Sending Information . POST, PUT
HTML Security • Reading HTML Source
HTML Security (2) • Hidden Fields • Server Side Includes
Common Gateway Interface(CGI) • Allows web pages to dosomething 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
Common Gateway Interface(CGI) (2) • Common Mistakes - Misuse of command interpreters - Bad memory management - Passing unchecked parameters to system
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
What About Non-PersistentCookies? • 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)
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
Secure Electronic Transactions(SET) • Developed by Visa, MasterCard, Microsoft, Netscape • Specific-purpose protocol • Secures credit and debit card transactions
Secure Electronic Transactions(SET) (2) • Services provided - Authentication - Confidentiality - Message Integrity - Linkage
Active Content • Programs that interact in a network environment • Java/ActiveX
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