How I Met Your Sweetheart: - PowerPoint PPT Presentation

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How I Met Your Sweetheart:

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  1. How I Met Your Girlfriend: The discovery and execution of entirely new classes of Web attacks in order to meet your girlfriend. Samy Kamkar samy@samy.pl http://samy.pl Twitter: @SamyKamkar

  2. Who is samy? • "Narcissistic Vulnerability Pimp" (aka Security Researcher for fun) • Author of The Samy Worm on MySpace • Co-Founder of Fonality, IP PBX company • Chick Magnet [citation needed] • Lady Gaga aficionado

  3. Cyber Warrior • Raided • Computer use lost • Tweens everywhere disappointed

  4. Why the web? • It’s new, it’s cool, it’s exploitable! • Gopher isn’t used as much anymore • The web is a code distribution channel • Browsers can communicate in ways they don’t know • And much more!

  5. My Homepage • It’s new, it’s cool, it’s exploitable! • Gopher isn’t used as much anymore • The web is a code distribution channel • Browsers can communicate in ways they don’t know • And much more!

  6. Attack Indirectly • Certified Information Security Specialist Professional • Chief Executive Officer of SecTheory • Co-Author of « XSS Exploits: Cross Site Scripting Attacks and Defense » • Author of « Detecting Malace » • Co-developer of Clickjacking with Jeremiah Grossman • Runs ha.ckers.org and sla.ckers.org • Certified ASS (Application Security Specialist)

  7. Attack Indirectly • Robert « Rsnake » Hansen • How do we attack someone who secures himself well? • Don’t.

  8. Attack Indirectly • XSS? Probably won’t fall for it. • CSRF? Same.

  9. PHP: Overview • PHP: extremely common web language • PHP sessions: extremely common default session management • PHP sessions: used by default in most PHP frameworks (e.g., CakePHP) • PHP sessions: either passed in URL or…

  10. PHP Sessions: Overview • session_start() – initialize PHP session

  11. PHP Sessions: Entropy • session_start()’s pseudo-random data: • IP address: 32 bits • Epoch: 32 bits • Microseconds: 32 bits • Random lcg_value() (PRNG): 64 bits • TOTAL: 160 bits • SHA1’d: 160 bits • 160 bits = a lot = 1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976

  12. How big is a bit? Some tricks • For every 10 bits, add ~3 zeros • 10 bits = 1,024 (thousand) • 20 bits = 1,048,576 (mil) • 30 bits = 1,073,741,824 • 25 bits = ~32,000,000

  13. It’s Just Math! • 160 bits = 2 ^ 160 = ~10 ^ 48 • 160 bits = 1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976 • At 100 trillion values per second, 160 bits would take… • (2 ^ 160) / (10 ^ 14) / (3600 * 24 * 365 * 500000000) = 926,878,258,073,885,666 = 900 quadrillion eons • 1 eon = 500 million years

  14. PHP Sessions: Entropy • session_start()’s pseudo-random data: • IP address: 32 bits • Epoch: 32 bits • Microseconds: 32 bits • Random lcg_value() (PRNG): 64 bits • TOTAL: 160 bits • SHA1’d: 160 bits • 160 bits = a lot = 1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976

  15. PHP Sessions: Entropy Redux • Not so pseudo-random data: • IP address: 32 bits • Epoch: 32 bits • Microseconds: 32 bits • only 0 – 999,999 … 20 bits = 1,048,576 • < 20 bits! (REDUCED) -12 bits • Random lcg_value() (PRNG): 64 bits • TOTAL: 148 bits (reduced by 12 bits) • SHA1’d: 160 bits

  16. An Example: Facebook

  17. PHP Sessions: Entropy Redux • Not so pseudo-random data: • IP address: 32 bits • Epoch: 32 bits (ACQUIRED) -32 bits • Microseconds: 32 bits • only 0 – 999,999 … 20 bits = 1,048,576 • < 20 bits! (REDUCED) -12 bits • Random lcg_value() (PRNG): 64 bits • TOTAL: 116 bits (reduced by 44 bits) • SHA1’d: 160 bits

  18. An Example: Facebook

  19. PHP Sessions: Entropy Redux • Not so pseudo-random data: • IP address: 32 bits (ACQUIRED) -32 bits • Epoch: 32 bits (ACQUIRED) -32 bits • Microseconds: 32 bits • only 0 – 999,999 … 20 bits = 1,048,576 • < 20 bits! (REDUCED) -12 bits • Random lcg_value() (PRNG): 64 bits • TOTAL: 84 bits (reduced by 76 bits) • SHA1’d: 160 bits

  20. PHP LCG (PRNG): Randomness • php_combined_lcg() / PHP func lcg_value()

  21. PHP LCG (PRNG): Randomness • S1 WAS 32 bits, NOW 20 bits • SEED (s1+s2): 64 bits – 12 bits = 52 bits

  22. PHP LCG (PRNG): Randomness • LCG(s2) = (long) getpid(); • S2 = 32 bits • Linux only uses 15 bits for PIDs • S2 = 32 bits – 17 bits = 15 bits • SEED (s1+s2) = 15 bits + 20 bits = 35 bits • PHP function: getmypid() • Linux command: ps • Learn PID, reduce the other 15 bits! • SEED (s1+s2) = 0 bits + 20 bits = 20 bits

  23. PHP Sessions: Entropy Redux • Not so pseudo-random data: • IP address: 32 bits (ACQUIRED) -32 bits • Epoch: 32 bits (ACQUIRED) -32 bits • Microseconds: 32 bits • only 0 – 999,999 … 20 bits = 1,048,576 • < 20 bits!(REDUCED) -12 bits • Random lcg_value (REDUCED) -44 bits • TOTAL: 40 bits (reduced by 120 bits) • SHA1’d: 160 bits

  24. PHP Sessions: Entropy Redux • Microseconds: 32 bits down to 20 bits • Random lcg_value down to 20 bits • 40 bits? No! We can calc lcg_value() first! • With a time-memory trade-off (4 MB), we can learn the lcg_value original seed in a few seconds, REDUCING to 20 bits! • 40 bits – 20 bits = 20 bits 20 bits = 1,048,576 cookies

  25. GREAT SUCCESS! • 500,000 requests on average! • Can be completed in a day

  26. You down with entropy?Yeah you know me! • PHP 5.3.2: a bit more entropy • Create your own session values! • Attack is difficult to execute! • PS, Facebook is NOT vulnerable! • <3 Facebook • Please help my farmville * Thanks to Arshan Dabirsiaghi and Amit Klein for pointing me in the right direction

  27. GREAT SUCCESS! • Using victim’s cookie, message our new victim with a malicious link!

  28. This is your network.

  29. This is your network on drugs.

  30. A NAT

  31. Cross-Protocol Scripting (XPS) • HTTP servers can run on any port • A hidden form can auto-submit data to any port via JS form.submit() • HTTP is a newline-based protocol • So are other protocols….hmmmm

  32. Cross-Protocol Scripting:Examples in the real world • Let’s write an IRC client  in HTTP! • This uses the CLIENT’s computer to connect, thus using their IP address!

  33. XPS IRC Example

  34. NAT Pinning: cont.

  35. HTTP POST w/IRC content

  36. NAT Pinning: XPS times OVER 9,000 • Sweet! So what is NAT Pinning? • NAT Pinning confuses not only the browser, but also the ROUTER on the application layer • E.g., when communicating with port 6667, browser thinks HTTP, router thinks IRC • We can exploit this fact and use router conveniences to attack client

  37. Cross-Protocol Scripting (XPS) and NAT Pinning: Introduction

  38. NAT Pinning: IRC DCC • linux/net/netfilter/nf_conntrack_irc.c • DCC chats/file sends occur on a separate port than chat • Client sends: PRIVMSG samy :DCC CHAT samy IP port • Router sees IP (determined from HTTP_REMOTE_ADDR) and port, then FORWARDS port to client! • ANY PORT!

  39. NAT Pinning: cont.

  40. NAT Pinning: blocked ports • If browser doesn’t allow outbound connections on specific ports? • TCP / UDP ports = 16 bits = 65536 • So overflow the port! 65536 + 6667

  41. NAT Pinning: blocked ports • 6667 + 65536 = 72203 • 6667 = 00001101000001011 • 72203 = 10001101000001011 • Some browsers check: if port == 6667 … but 72203 != 6667 • Correct check: port % 2^16 * Webkit integer overflow discovered by Goatse Security

  42. NAT Pinning: prevention • Strict firewall – don’t allow unknown outbound connections • Client side – run up to date browser • Client side – use NoScript if using Firefox • Client side – run local firewall or tool like LittleSnitch to know if an application is accessing unknown ports

  43. Penetration 2.0

  44. TRIPLE X

  45. TRIPLE X SS

  46. Geolocation via XXXSS

  47. Geolocation via XXXSS • Anna visits malicious site