Bluetooth unlock signal of the parcel box can be recorded and replayed
Admin & Söhne smart parcel box · firmware, Bluetooth unlock
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Description
Admin & Söhne sells a smart parcel box that customers unlock with the app over Bluetooth. The unlock message is the same every time: it contains no counter or changing code. Someone standing nearby while the owner opens the box can record this message and send it again later to open the box without the app.
Steps to reproduce
- Pair test box A with a test account and unlock it once from the app.
- Record the Bluetooth unlock message from a few metres away.
- Later, with the app closed, send the recorded message again: box A unlocks.
Unlock message, 1st use: 0x5A 0x01 … 0x7C (redacted)
Unlock message, 2nd use: 0x5A 0x01 … 0x7C (identical)
Replay after 24 h → box state "unlocked" Business impact
A thief who stands nearby once can empty the box later. Missing replay protection is exactly what EN 18031 checks, so it can block CE marking and force an update or a recall of every box sold.
Remediation
Add a challenge-response step: the box sends a fresh random value, and the app must answer with a signed reply that is valid only once. Ship the fix as a firmware update and log unlock attempts with old or repeated messages.
OWASP IoT Top 10 2018: I3 Insecure Ecosystem Interfaces · CWE-294 (Authentication Bypass by Capture-replay) · EN 18031-1