Micca KE700 Acceptance of previously used rolling codes
The Micca KE700 system contains flawed resynchronization logic and is vulnerable to replay attacks. This attack requires sending two previously captured codes in a specific sequence. As a result, the system can be forced to accept previously used (stale) rolling codes and execute a command. Successful exploitation allows an attacker to clone the alarm key. This grants the attacker unauthorized access to the vehicle to unlock or lock the doors.
Description: CAPEC-395: Bypassing Electronic Locks and Access Controls
Solutions
* Enforce strict anti-replay: The receiver must maintain a persistent state (e.g., the counter value of the last valid code). It must never accept a code with a counter value less than or equal to the last known valid counter.
* Secure resynchronization logic: The logic triggered by an old code is the flaw and must be removed. Secure resynchronization should only be triggered by codes that are ahead of the current counter to allow a "drifted" key fob to re-sync.