A team of security researchers found that several modern Honda car models have a vulnerable rolling code mechanism that allows unlocking the cars or even starting the engine remotely.
Called Rolling-PWN, the weakness enables replay attacks where a threat actor intercepts the codes from the keyfob to the car and uses them to unlock or start the vehicle.
The researchers claim to have tested the attack on Honda models between 2021 and 2022, including the popular models below:
- Honda Civic 2012
- Honda X-RV 2018
- Honda C-RV 2020
- Honda Accord 2020
- Honda Odyssey 2020
- Honda Inspire 2021
- Honda Fit 2022
- Honda Civic 2022
- Honda VE-1 2022
- Honda Breeze 2022
Intrinsic weakness
The keyless entry system in modern cars rely on rolling codes produced by a pseudorandom number generator (PRNG) algorithm to ensure that unique strings are used each time the keyfob button is pressed.
The rolling code mechanism was introduced to prevent fixed code flaws that enabled man-in-the-middle replay attacks.
Vehicles have a counter that checks the chronology of the generated codes, increasing the count upon receiving a new code. Non-chronological codes are accepted, though, to cover situations of accidental presses of the keyfob, or when the vehicle is out of range.
An attacker equipped with software-defined radio (SDR) equipment could capture a consecutive sequence of codes and replay them at a later time to unlock the vehicle and starts its engine.
The researchers provided details about the Rolling-PWN issue along with several videos showing how it could be used to unlock various Honda models.
The vulnerability is tracked as CVE-2021-46145 (medium severity) and is described as an issue "related to a non-expiring rolling code and counter resynchronization" in the keyfob subsystem in Honda.
Honda denies there's a problem
The researchers tried to notify Honda of the vulnerability but could not find a contact for reporting security-related issues. In the end, they filed a report to Honda Customer Service but have not heard back.