COSIC Ashur, Benedikt Gierlichs and Bart Preneel an imec research - - PowerPoint PPT Presentation

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COSIC Ashur, Benedikt Gierlichs and Bart Preneel an imec research - - PowerPoint PPT Presentation

Nov 19, 2023 405 likes •868 views

Fast, Furious and Insecure Lennert Wouters , Eduard Marin, Tomer COSIC Ashur, Benedikt Gierlichs and Bart Preneel an imec research group at KU Leuven Lennert Wouters , Eduard Marin, Tomer Ashur, Benedikt Gierlichs and Bart Preneel Passive

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SLIDE 1

Fast, Furious and Insecure

Lennert Wouters, Eduard Marin, Tomer Ashur, Benedikt Gierlichs and Bart Preneel Lennert Wouters, Eduard Marin, Tomer Ashur, Benedikt Gierlichs and Bart Preneel

COSIC

an imec research group at KU Leuven

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COSIC

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Passive Keyless Entry and Start

Response Challenge

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The Tesla Model S key fob

TI TMS37F128 (X-Ray) MSP430 (MCU) TMS37126 (transponder) SPI PCB front PCB back UHF antenna 3D LF antenna MicRF112 transmitter IC

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TMS37F128

Source: http://www.ti.com/lit/ds/symlink/tms37f128.pdf

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  • Cannot order the IC’s from Farnell/Digikey
  • Uncommon package (30 pin TSSOP – 0.5mm pitch)
  • Almost no public information on these chips (NDA)
  • The information that is available is inconsistent

5

Getting started

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Slave Master

SPI

6

Connecting to the TMS37126

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The Serial Peripheral Interface (SPI)

Source: http://www.ti.com/lit/an/spna147/spna147.pdf

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  • SPI BUSY line indicates when the slave is ready for the next byte
  • The transponder indicates an error by pulling busy high or low for a long

period

  • Observation 1:
  • Error if CMD value is incorrect
  • Observation 2:
  • If LEN is 0xFF and the CMD value is correct we get an error after the

correct number of bytes (LEN) has been sent

8

Uncovering undocumented SPI commands

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COSIC

Action LEN CMD WA DST40(C, K1) 0x06 0x84 NA DST_UNK(C, K1) 0x06 0x85 NA DST40(C, K2) 0x06 0x86 NA DST_UNK(C, K2) 0x06 0x87 NA Change K1 0x07 0x01 0x11 Change K2 0x07 0x01 0x12

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Uncovering undocumented SPI commands

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COSIC

  • Olimex MSP430-JTAG-TINY-V2 programmer
  • JTAG fuse wasn’t blown

10

Obtaining MSP430 firmware

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COSIC

  • Interrupt Vector Table (IVT)
  • References to Special Function Registers (SFR)
  • SPI transmit and receive buffers

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MSP430 Static firmware analysis

More info: POC||GTFO 0x11: A TOURIST'S GUIDE TO MSP430

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COSIC

  • MSPDebug + Olimex MSP430-JTAG-TINY-V2
  • MSP430F1232 supports up to two breakpoints
  • Caveat: some debug pins are shared with IO and can trigger interrupts
  • Inspect interesting routines + dump RAM and register values
  • Retrieve bytes exchanged over SPI
  • The firmware is only using CMD 0x86 (DST40) during normal operation

12

MSP430 Dynamic firmware analysis

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COSIC

  • DST40
  • Introduced in 2000
  • 40-bit key
  • Security Analysis of a Cryptographically-Enabled RFID Device (2005)
  • S Bono, M Green, A Stubblefield, A Juels, AD Rubin
  • Used for immobilizer by Ford, Lincoln, Mercury, Nissan and Toyota
  • Exxon-Mobil’s Speedpass payment system

13

Texas Instruments Digital Signature Transponder (DST)

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DST40 Cipher

Key schedule is executed every 3rd round starting in the 2nd Challenge register Key register

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RF reverse engineering

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  • Two separate systems:
  • Remote Keyless Entry (RKE)
  • Actions are performed by pressing a button
  • One way communication
  • Passive Keyless Entry and Start (PKES)
  • The car is unlocked automatically if the key fob is in proximity of the vehicle
  • Two way communication

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Key fob RF operation

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COSIC

  • One way communication from key fob to the vehicle
  • Physical layer information:
  • Operating frequency: 433.92 MHz
  • Modulation: ASK
  • Symbol rate: 2600 symbols/S

17

Remote Keyless Entry (RKE)

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COSIC

  • Both key fob and car store a 40-bit counter
  • Key fob increments counter and calculates new response

18

Remote Keyless Entry

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19

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COSIC

  • Low Frequency (134.2 kHz)
  • From car to key fob
  • Ultra High Frequency (433.92 MHz)
  • From key fob to car

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Passive Keyless Entry and Start

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COSIC

  • Proxmark3
  • Added DST transponder code for the AT91SAM microcontroller
  • Hardware modification to boost receiver range
  • Custom peak detect code for the FPGA

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Low Frequency

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Receiving LF signals

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PKES Protocol analyzer

Yard Stick One (UHF) Proxmark 3 (LF)

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PKES protocol

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  • Receive the 40-bit challenge
  • ~216 keys produce the correct response
  • Guess a key and transmit the response
  • After on average 223 guesses you will have a valid

challenge response pair

  • Assuming 1 guess per second → 97 days
  • Can be automated

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A car only attack

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Proof of Concept

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  • 40-bit challenge is combined with a 40-bit key resulting in a 24-bit response
  • For each 40-bit challenge multiple keys produce the same response
  • Need two challenge response pairs to recover the key
  • Brute force using 16 FPGAs took 1 hour in 2005

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DST40 key recovery

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COSIC

  • The key fob cannot verify the sender of a challenge
  • The key fob replies to any challenge it receives

as long as the car ID is correct

  • Time-Memory Trade-Off Table
  • Simplified pseudocode:
  • 224 files each containing ~216 40-bit keys

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DST40 key recovery

challenge = 0x636f736963 for key in range (0, 240): response = DST40(challenge, key) responseFile.append(key)

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COSIC

  • Retrieve the 2-byte car ID (sniff or brute force)
  • Send challenge 0x636f736963 to the key fob
  • Use the response to select the correct TMTO file
  • Send a different challenge and record the response
  • Test the remaining ~216 keys

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Cloning a key fob

for key in TMTO_File: resp = DST40(challenge2, key) if resp == response2: return key

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Proof of Concept attack

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Responsible disclosure

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  • First notified Tesla on 31/08/2017
  • Tesla vehicles produced from June 2018 onwards use a new key fob
  • OTA update includes a Pin to Drive feature and the ability to disable PKE

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Responsible disclosure

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38 Source: https://cars.mclaren.com/ownership/recalls-1

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“We have been alerted to a potential new security risk that may affect McLaren as well as the products of several other luxury automotive brands. The “relay attack” that has previously been reported in the media suggested that a car key could be scanned if left within range of the vehicle and the car driven

  • away. The car, however, cannot be restarted as the key was still with its owner.”

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McLaren Automotive (1)

Source: https://cars.mclaren.com/ownership/recalls-1

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COSIC

“A second potential method involves the vehicle being scanned by custom equipment left in close-proximity and decoded in ~100 days. A cloned key can be produced as above.” To reassure you, the method is currently considered as a low-risk by experts because the custom equipment required for such a breach, while feasible, requires skilled assembly and use.”

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McLaren Automotive (2)

Source: https://cars.mclaren.com/ownership/recalls-1

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COSIC

“The equipment also needs to be in very close proximity to a key. To further reassure you, the vulnerability has not been proven to affect our vehicles and we know of no McLaren that has been compromised in such a way.”

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McLaren Automotive (3)

Source: https://cars.mclaren.com/ownership/recalls-1

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COSIC

“Nevertheless, we take the security of all McLaren vehicles extremely seriously.” – McLaren, 2018

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McLaren Automotive (4)

Source: https://cars.mclaren.com/ownership/recalls-1

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COSIC

  • Don’t blindly rely on:
  • proprietary cryptography
  • secrecy of datasheets or parts that require an NDA
  • your suppliers, work with them
  • the secrecy of firmware (but do disable debug interfaces)
  • Don’t reuse keys
  • Lock It and Still Lose It - Flavio D. Garcia, David Oswald, Timo Kasper, Pierre Pavlidès
  • Breaking KeeLoq in a Flash - Markus Kasper, Timo Kasper, Amir Moradi, Christof Paar
  • If you design a product: familiarize yourself with existing security issues

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Conclusions

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Conclusions

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Conclusions: stock price

?

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an imec research group at

Questions?

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@LennertWo @CosicBe lennert.wouters@esat.kuleuven.be