What's in your pocket? (BSides Manchester)

Although we’re starting to see computers built into lightbulbs and refrigerators, we’ve been quietly surrounded by smaller computers all along. SIM cards, modern passports, student cards, transit cards, and access cards contain microprocessors featuring limited storage and cryptographic abilities. This talk explores what data smartcards store and how they protect the stored data.

Transcript

1. what’s in your pocket? Henri Watson
2. $ whoami • Software Engineering Intern at Judo Payments • Second year student at Abertay University (HackSoc Secretary + Securi-Tay 2017 Organiser) • Lived in the Dominican Republic for 13 years • I dig • Payments technologies • Security UX • Embedded devices • Public transportation
3. Smartcards are often used as replacements for magnetic stripe cards
4. They rapidly grew in popularity as a result of their trusted and secure nature
5. Take a look at your wallet • GPG card • Bank card • Laundry card • Transit card • Identity documents • Hotel/office key • Student card • Single Sign On card
6. Take a look at your appliances • Satellite decoder cards • SIM cards • Gas/electricity top-up card
7. We are surrounded by smartcards
8. …but perhaps we haven’t stopped to consider their security implications
9. …or the data held on them
10. We directly interact with the data held on magnetic stripe cards http://samy.pl/magspoof/iron-oxide-short-low.gif
11. Directly interacting with a smartcard’s EEPROM is impractical
12. http://people.cs.uchicago.edu/~dinoj/smartcard/security.html
13. Realistically, there is no “data” on the smartcard that can be cloned
14. We’re not interested in a smartcard’s data, instead we care about its responses to commands.
15. We have to speak with the smartcard to inspect its contents
16. or
17. Contact cards are defined by ISO/IEC 7816
18. Contactless cards are defined by ISO/IEC 14443
19. Contactless cards are defined by ISO/IEC 14443 (Uses ISO/IEC 7816’s T=1 protocol)
20. Contactless cards are defined by ISO/IEC 14443 (Uses ISO/IEC 7816’s T=1 protocol) (so it’s sorta the same, but more interference)
21. https://commons.wikimedia.org/wiki/File:Australia_Bank_Paypass_Card.png
22. Smartcards are varyingly clever ASICs
23. Many run JavaCard, a stripped down Java Virtual Machine
25. Others are more purpose-built ASICs
26. Let’s ask a smartcard to do something
27. Card Reader
28. Card Reader
29. Card Reader 3B 88 80 01 E1 F3 5E 11 77 83 B7 00 17
30. 3B 88 80 01 E1 F3 5E 11 77 83 B7 00 17 https://smartcard-atr.appspot.com/
31. 3B 88 80 01 E1 F3 5E 11 77 83 B7 00 17 (UK Biometric Residence Permit)
32. 3B 88 80 01 00 00 00 00 80 81 71 00 79 Apple Pay 3B 81 80 01 80 Oyster Card / MIFARE DESFire 3B 8F 80 01 80 4F 0C A0 00 00 03 06 03 00 02 00 00 00 00 69 Scottish National Entitlement Card / MIFARE Classic 4k 3B 89 80 01 66 52 57 45 32 50 52 4F 4D 1C Glasgow Subway Card / ITSO
33. Card Reader
34. Card Reader
35. except not really
36. Card Reader
37. Card Reader
38. ¯\_(ツ)_/¯
39. but let’s assume you have a handshake
40. …then it’s up to the application
41. Applications usually implement a handful of standard commands • READ BINARY • WRITE BINARY • UPDATE BINARY • ERASE BINARY • READ RECORD • WRITE RECORD • APPEND RECORD • UPDATE RECORD • GET DATA • PUT DATA • SELECT FILE • VERIFY
42. These commands are specified by Global Platform
43. …but it’s cool to ignore them
44. Talking with a random card is a headache
45. but let’s assume you also know what commands the card supports
46. As a simple example, let’s look at basic GSM authentication
47. Phone Cell tower Ki: ABCDEFGHIJKLMNO
48. SIM Card Phone Remaining PINs: 3 Ki: ABCDEFGHIJKLMNO
49. SIM Card Phone Remaining PINs: 2 Ki: ABCDEFGHIJKLMNO
50. SIM Card Phone Remaining PINs: 2 Ki: ABCDEFGHIJKLMNO
51. SIM Card Phone Remaining PINs: 3 Ki: ABCDEFGHIJKLMNO
52. SIM Card Phone Remaining PINs: 3 Ki: ABCDEFGHIJKLMNO
53. SIM Card Phone Remaining PINs: 3 Ki: ABCDEFGHIJKLMNO
54. Phone Cell tower Ki: ABCDEFGHIJKLMNO
55. In this example, the SIM card demonstrates two access control methods
56. The SIM card protects the PIN and the Ki
57. As the SIM card performs cryptographic operations on-board, the Ki isn’t exposed
58. …unless you brute-force it
59. SIM Card Reader Remaining PINs: 3 Ki: ABCDEFGHIJKLMNO http://www.isaac.cs.berkeley.edu/isaac/gsm-faq.html
60. We also have smartcards in our bank cards
61. EMV attempts to provide a secure payments environment in an assumed hostile environment.
62. Multiple applications per card are used in the United States to allow debit cards to be run in stores over the credit network or the debit network. * Supporting this is legally required as a result of the Durbin Amendment
63. Smartcards are also used for more generic data storage
64. Some of these are MIFARE Ultralight cards
65. Mostly publicly readable, basic access control settings
68. Many of these are MIFARE Classic cards
69. Card Reader
71. Some people store data on these cards
72. …but this is all safe because you need encryption keys to read and write
73. https://eprint.iacr.org/2009/137
75. Not everyone uses MIFARE Classic though
76. NXP touts MIFARE DESFire as being safer
77. DESFire cleanly supports multiple applications and has a stronger ACS
78. https://codebutler.github.io/farebot/
79. http://www.proxmark.org/files/Documents/13.56%20MHz%20- %20MIFARE%20DESFire/Cloning_Cryptographic_RFID_Cards_for_25USD-WISSEC_2010.pdf
81. https://www.itso.org.uk/wp-content/uploads/2012/07/ISAM_small.jpg
82. https://www.itso.org.uk/wp-content/uploads/2014/11/ITSO-Application-layers.jpg
84. …but there are other applications
85. …but there are other applications …like passports
86. Passports have sensitive data that must be protected
88. Passport Reader
89. This is all numeric data
90. This is all numeric data …that we can bruteforce
91. http://hgi.ruhr-uni-bochum.de/media/crypto/veroeffentlichungen/2011/01/29/ epasscrack_otm07.pdf
92. so basically
93. It’s impractical to attack the smartcard itself
94. Instead, attacks rely on broken crypto or side channel leaks
95. Cards run very small and heavily optimised applications
96. There’s a lot of software that allows you to interact with known smartcards
97. You can build your own smartcards too
98. https://simhacks.github.io/defcon-21/
99. There are tiny computers in all of our pockets
100. Say hello to them
101. Say hello to them maybe they’ll say hi back
102. Thanks! @henriwatson henri@henriwatson.com https://henriwatson.com/talks/yourpocket