1. SSLstrip Stepan Shykerynets http://wisc.org.ua/ 23.03.2013

5. ! Attention http://wisc.org.ua/ 23.03.2013

10. Private / Public key Public key Private key SERVERCLIENT http://wisc.org.ua/ 23.03.2013

11. Private / Public key Public key Private key SERVERCLIENT Public keyCA http://wisc.org.ua/ 23.03.2013

12. Private / Public key Public key Private key SERVERCLIENT Public key CA http://wisc.org.ua/ 23.03.2013

13. Private / Public key MessagePublic key Encrypted message Private keyMessage http://wisc.org.ua/ 23.03.2013

14. SSL And Certificate Chaining http://wisc.org.ua/ 23.03.2013

15. Certificate X509 Certificate version serial number issuer validity subject public key Signature algorithm Signature http://wisc.org.ua/ 23.03.2013

16. Certificate Chaining CA Certificate Embedded in browser. All powerful. Certifies that a site certificate is authentic. Site Certificate Identifies a particular URL. Is known to be authentic based on CA Certificate's signature. http://wisc.org.ua/ 23.03.2013

17. Certificate Chaining CA Certificate Embedded in browser. All powerful. Certifies that a site certificate is authentic. Site Certificate Identifies a particular URL. Is known to be authentic based on CA Certificate's signature. Intermediate CA Not embedded in browser. Still sort of all-powerful. Certifies that a site certificate is authentic. http://wisc.org.ua/ 23.03.2013

18. Certificate Chaining VeriSign Facebook.com Intermediate CA http://wisc.org.ua/ 23.03.2013

19. Certificate Chains Can Be > 3 VeriSign Facebook.com Intermediate CA http://wisc.org.ua/ 23.03.2013

20. How do we validate these things? Verify that the leaf node has the name of the site you're connecting to. Verify that the leaf node hasn't expired. Check the signature. If the signing certificate is in our list of root CA's, stop. Otherwise, move one up the chain and repeat. http://wisc.org.ua/ 23.03.2013

21. Very tempting to use a simple recursive function. Everyone focuses on the signature validation. The result of a naive attempt at validation is a chain that is complete, but nothing more. http://wisc.org.ua/ 23.03.2013

22. What if … VeriSign hack.org Intermediate CA http://wisc.org.ua/ 23.03.2013

23. What if … VeriSign hack.org Intermediate CA Facebook.com http://wisc.org.ua/ 23.03.2013

24. What they say : Verify that the leaf node has the name of the site you're connecting to. Verify that the leaf node hasn't expired. Check the signature. If the signing certificate is in our list of root CA's, stop. Otherwise, move one up the chain and repeat. http://wisc.org.ua/ 23.03.2013

25. But … All the signatures are valid Nothing has expired The chain is in fact The root CA is embedded in the browser and trusted http://wisc.org.ua/ 23.03.2013

26. The missing piece http://wisc.org.ua/ 23.03.2013

27. The missing piece ! http://wisc.org.ua/ 23.03.2013

28. The missing piece http://wisc.org.ua/ 23.03.2013

29. Most CA's didn't explicitly set basic Constraints: CA=FALSE A lot of web browsers and other SSL implementations didn't bother to check it, whether the field was there or not Any one with a valid leaf node certificate could create and sign a leaf node certificate for any other domain. http://wisc.org.ua/ 23.03.2013

30. But we have one problem http://wisc.org.ua/ 23.03.2013

31. Smart browsers http://wisc.org.ua/ 23.03.2013

32. People are … http://wisc.org.ua/ 23.03.2013

33. People are … LAZY http://wisc.org.ua/ 23.03.2013

34. http://... https://... http://wisc.org.ua/ 23.03.2013

35. SSLsniff http://wisc.org.ua/ 23.03.2013

36. SSLsniff Intercept a connection from the client side. Generate a certificate for the site it is connecting to. Sign in with any random valid leaf node certificate. Pass that certificate chain to the client. Make normal SSL connection to the server. Pass data between client and server, decrypting and encrypting on each end. http://wisc.org.ua/ 23.03.2013

37. Web browsing SSL is almost never encountered directly. It is either encountered as a result of: A 302 redirect from HTTP URL to an HTTPS URL. An HTTPS link that a user click on from an HTTP page. http://wisc.org.ua/ 23.03.2013

38. SSLstrip Watch HTTP traffic go by. Switch to and keep a map of what you've changed. Switch Location: https:// to Location: http:// and keep a map of what you've changed. http://wisc.org.ua/ 23.03.2013

39. SSLstrip Watch HTTP traffic go by. When we seen an HTTP request for URL that we've stripped, proxy that out as HTTPS to the server. Watch the HTTPS traffic go by, log everything that we want, and keep a map of all relative, CSS and JS links that go by. http://wisc.org.ua/ 23.03.2013

40. SSLstrip The server never knows the difference. Everything looks secure on their end. The client doesn't display any of the disastrous warnings that we want to avoid. We see all the traffic. http://wisc.org.ua/ 23.03.2013

41. Let's simplify it…

42. Time to action http://wisc.org.ua/ 23.03.2013

43. BackTrack : Giving Machine Guns to Monkeys since 2006 http://wisc.org.ua/ 23.03.2013

44. Tools SSLstrip ARPspoof Ettercap http://wisc.org.ua/ 23.03.2013

45. Commands #bt echo "1" > /proc/sys/net/ipv4/ip_forward # bt iptables -t nat -A PREROUTING -p tcp -- destination-port 80 -j REDIRECT --to-port 10000 #bt sslstrip -a -l 10000 -w log.txt –f # arpspoof -i -t # ettercap -T –q –i http://wisc.org.ua/ 23.03.2013

46. Protection Google services High protection network equipment Checking site certificates http://wisc.org.ua/ 23.03.2013

47. Stepan Shykerynets SShykerynets@gmail.com