Security in Online Banking

1. Joel Fendrick Security in Online Banking

2. Overview • Encryption Methods • AES (Advanced Encryption Standard) • SSL (Secure Socket Layer) • TLS (Transport Layer Security) • TLS Advantage Over SSL • Security Example • Attacks • Countermeasure

3. Encryption Methods • Asymmetric • Symmetric • Hashing

4. Asymmetric • Each user has two keys • Private • Public • Public key stored in public database • Messages encrypted with public key can only be decrypted with private key. • Encrypted with private -> decrypted with public

5. Symmetric • No private/public • Only means of decryption is if you have the right key • Security issue in exchanging the key

6. Hashing • Unique fixed length string of characters from selected text • One way process • Cannot recreate document from hash • If anything changes in text, hash would change • Can be used to determine integrity of file

7. Suppose hash of a document was: 9c5292056062f70a2f14330cf4d30c7f If anything at all changes in document a new hash is formed 91857f37a636882c78de9961e791c81a Making it easy to tell if the message has been altered in any way

8. AES (Advanced Encryption Standard) • Cryptographic algorithm used to protect electronic data • Block cipher that can encrypt and decrypt information • Capable of using keys of 128, 192, and 256 bits • Encrypts data into blocks of 128 bits

9. Pseudo code http://www.garykessler.net/library/crypto.html#fig17

10. in[] and out[] • 16-byte arrays with the plaintext and cipher text, respectively. (According to the specification, both of these arrays are actually 4*Nb bytes in length but Nb=4 in AES.) • w[] • array containing the key material and is 4*(Nr+1) words in length. (Again, according to the specification, the multiplier is actually Nb.) • state[] • a 2-dimensional array containing bytes in 4 rows and 4 columns. (According to the specification, this arrays is 4 rows by Nb columns.)

11. SubBytes •  takes the value of a word within a State and substitutes it with another value by a predefined S-box • ShiftRows • circularly shifts each row in the State by some number of predefined bytes • MixColumns • takes the value of a 4-word column within the State and changes the four values using a predefined mathematical function • AddRoundKey • XORs a key that is the same length as the block, using an Expanded Key derived from the original Cipher Key

12. Walkthrough • This walkthrough is of Rijndael encryption • Rijndael allows for both key and block sizes to be chosen independently from the set of { 128, 160, 192, 224,  256 } bits.  (And the key size does not in fact have to match the block size).  • However, the block size must always be 128 bits in AES, and the key size may be either 128, 192, or 256 bits. • http://www.formaestudio.com/rijndaelinspector/

13. AES Flaw • 2009 weakness identified • Interesting in mathematical P.O.V. • Not really relevant in application • Finding the key of AES is four times easier than previously believed • Steps to find = 8 followed by 37 zeroes

14. 1 trillion machines each test 1 billion keys per second • Would take more than 2 billion years to recover AES-128 key • AndreyBogdanov (K.U.Leuven), • Dmitry Khovratovich (Microsoft Research), • Christian Rechberger (ENS Paris)

15. SSL (Secure Socket Layer) • 3 basic properties • Connection is private • Peer’s identity can be authenticated using asymmetric cryptography • Connection is reliable • message check using keyed Message Authentication Code (MAC)

16. Two layers: can include length description and content • Lowest Layer = SSL Record Protocol • Second Layer = Handshake Protocol

17. TLS (Transport Layer Security) • Two layers • TLS Record Protocol • TLS Handshake Protocol • Encapsulates higher level protocols

18. TLS Record Protocol • Two basic properties • The connection is private • Symmetric Data encryption • The connection is reliable • Keyed MAC included in each message

19. TLS Handshake Protocol • Three basic properties • Peer’s identity can be authenticated using asymmetric or public key cryptography • The negotiation of a shared secret is secure • The negotiation is reliable

20. Advantage over SSL • Application protocol independent • Higher level protocols can layer on top of it transparently • Decisions on how to initiate TLS handshaking and how to interpret authentication certificates are left up to the designers of the higher level protocols

21. Security Example • Either SSL or TLS protocol • We’ll focus on SSL since it is the basis for TLS

22. Browser sends message via SSL to bank server • Bank responds by sending a certificate • Includes banks public key • Browser authenticates certificate and generate random session key • Uses this key to encrypt the data

23. Bank’s server receives session key and decrypts • Key was sent encrypted by bank’s public key • Bank uses private key to decrypt • Session key that now both bank and client know is used for rest of communication

25. Banks Didn’t Use SSL? • Bank of America • Wachovia • US Bank • Chase • American Express • Etc. • SSL login form listed as optional • Outside the US at this time HSBC was the only known bank not to use SSL authentication • British multinational banking and financial services company As of 2006 a number of big banks were not requiring the use of SSL authentication

26. Attacks • Man-in-the-middle • Man-in-the-browser

27. Man-in-the-middle • Someone intercepts the communication between two systems

28. Specific MITM Attack • Victim visits site that uses TLS 1.0 and receives a cookie, this cookie injects the client-side BEAST (Browser Exploit Against SSL/TLS) • Attacker can now use a network sniffer to look for active TLS connections • Grabs and decrypts the HTTPS cookie • Allows attacker to hijack victim’s session with that site.

29. Solution • Difficult • Attacks confidentiality VS authenticity like most attacks • Requires major change in the protocol itself • There are some fixes, but they cause compatibility issue with some existing SSL applications

30. Man-in-the-browser • Malware already infecting user computer • Kicks in after user has logged onto site • Hijack money and siphon it into criminal accounts

31. Solution • Use a trusted browser • Can be stored on a flash drive • Since stored in own secure environment it is not susceptible to malware in the same way as a traditional browser

32. Countermeasure • Historically piecemeal approach • Generally recommends several defenses that support each other • Often creates gaps within the layer architecture leaving some elements exposed to threats

33. Some banks implement a secure USB token • “provides secure online banking session even if computer is riddled with malware” • Read-only portable USB device • When plugged in encrypts the customers keystrokes • Launches virtualized OS • Launches secure browser • Launches a secure network between client and bank server

34. This is an attempt to create a virtual machine that is walled off from the rest of the PC • Protection from clients system • Makes sense that banks would want to protect their customers, as they are often the weakest link and biggest threat vector

35. Conclusion • Be careful and aware • Pay attention and confirm site is legitimate • Security is evolving , but so are the attacks

36. References • [1] HIPAA Collaborative of Wisconsin. (2010). The Basics of Encryption. Retrieved on March 22, 2012, from • http://www.hipaacow.org/docs/encryption%20whitepaper%207.7.10.doc • [2] NIST. (2001). Retrieved on March 22, 2012, from FIPS Publications website: http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf • [3] KatholiekeUniversiteit Leuven (2011, August 17). First flaws in the Advanced Encryption Standard used for internet banking identified. ScienceDaily. Retrieved on March 22, 2012, from http://www.sciencedaily.com­/releases/2011/08/110817075424.htm • [4] Dierks, T., & Rescorla, E. (2008, August). The Transport Layer Security (TLS) Protocol Version 1.2. Retrieved on March 22, 2012, from • http://tools.ietf.org/html/rfc5246 • [5] Freier, A., & Karlton, P. (2011, August). The Secure Sockets Layer (SSL) Protocol Version 3.0. Retrieved on March 22, 2012, from • http://tools.ietf.org/html/rfc6101 • [6] Onyszko, T. (2002, July 19). WindowsSecurity.com. Retrieved on March 23, 2012, from http://www.windowsecurity.com/articles/secure_socket_layer.html • [7] Online banking security and technical frequently asked questions. (2012). Retrieved on March 23, 2012, from http://www.bankofamerica.com/onlinebanking/index.cfm?adlink=&context=en&locale=&statecheck=WI&template=faq_security&cm_mmc=&cm_sp= • [8] Ou, G. (2006, April 27). Many banks failing to use ssl authentication. Retrieved on March 23, 2012, from • http://www.zdnet.com/blog/ou/many-banks-failing-to-use-ssl-authentication/201 • [9] OWASP. (2009, April 23). The open web application security project. Retrieved on March 23, 2012, from • https://www.owasp.org/index.php/Man-in-the-middle_attack • [10] Fisher, D. (2011, September 19). threatpost. Retrieved on March 23, 2012, from http://threatpost.com/en_us/blogs/new-attack-breaks-confidentiality-model-ssl-allows-theft-encrypted-cookies-091911 • [11] Bethlehem, D. (2012, February 12). Strong authentication by itself is not enough to prevent man-in-the-browser attacks. Retrieved on March 24, 2012, from http://data-protection.safenet-inc.com/2012/02/strong- • [12] Ramirez, D. (2007). Case study: Itu-t recommendation x.805 applied to an enterprise environment— banking. Bell Labs Technical Journal, 12(3), 55-64. • [13] (2011). Securing the weakest link. Bank Technology News,24(6), 1 & 35.