lecture2-tcp-ip-insecurity

lecture2-tcp-ip-insecurity - 1/15/09 Lecture 2 TCP/IP...

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1/15/09 1 1 Lecture 2 TCP/IP (In)Security Adrian Perrig 18-731: Network Security Spring 2009 2 Overview ± Administrative issues 630/730 prerequisite Syllabus page ± In this lecture TCP/IP vulnerabilities TCP SYN flooding TCP Daytona ± Upcoming lectures SSL/TLS BGP
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1/15/09 2 3 “Security Problems in the TCP/IP Protocol Suite” ± Paper by Steven Bellovin ± Interesting historical perspective ± Wakeup call for networking researchers, listing many security vulnerabilities ± Attacks studied in this lecture IP level attacks TCP level attacks Routing attacks ICMP attacks Application-level attacks 4 Security Issues in Broadcast Networks ± Security issues for communication between A, B, C, and Server? 2.0.0.0 1.0.0.0 1.1.1.1 1.1.1.2 Internet 2.1.1.1 1.1.1.3 A B C Server
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1/15/09 3 5 Basic Security Issues ± A ± S: P (using the IP protocol) ± How can S know that the packet originated from A? ± Can B overhear P? ± Can B impersonate A to S? ± Can C impersonate A to S? ± Note: eavesdropping or injection of arbitrary packets easy on most networks 6 Flaw: Use IP Address for Authentication ± IP source address can be easily spoofed! ± Easy to mount attack for another machine on the same network ± Example: r-utilities (rlogin, rsh, rcp) Consider Server trusts admin’s machine A If B spoofs A’s address, user on B can log in to Server Caveat? 1.1.1.1 1.1.1.2 1.1.1.3 A B Server
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1/15/09 4 7 Flaw: Use IP Address for Authentication ± Problem: A receives S’s responses to B’s spoofed packets, as the destination address is A! A will respond with a TCP Reset (RST) packet which closes the connection ± Solution: by overflowing A’s queues with connection requests, it is likely that A drops S’s replies ± Note: DoS attack used to enable another attack ± Other approaches to solve problem? 8 Flaw: Use IP Address for Authentication ± How can C impersonate A to S here? 2.0.0.0 1.0.0.0 1.1.1.1 1.1.1.2 Internet 2.1.1.1 1.1.1.3 A B C Server
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1/15/09 5 9 Other IP Level Attacks ± IP fragment attack Host stores fragments until entire packet arrived Attack: send individual fragments only, host wastes memory to store them Countermeasure? ± Smurf attack
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lecture2-tcp-ip-insecurity - 1/15/09 Lecture 2 TCP/IP...

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