A “hack-proof” smart padlock with security based on blockchain technology could be defeated by a simple Bluetooth replay attack – or a 1kg lump hammer.
The 360lock, a technologically enabled padlock (why?) was advertised by its creators as “completely hacking proof” and incorporating blockchain technology as used in the Ethereum cryptocurrency.
Its unique selling point is that the padlock can be locked and unlocked using an app that transmits over a Bluetooth Low Energy connection, rather than a physical key or combination lock. This apparently needed the inclusion of “advanced crypto codes” to drive “the level of security [to] maximum”.
Such silly claims caught the eye of Pen Test Partners, who not only hacked the “hack-proof” lock but also discovered that its physical security was crap too.
All that researcher David Lodge did was record a successful Bluetooth unlock command and then replay it, as he detailed on the company blog, referring to code snippets: “After I did the below commands it popped open. The first packet is authorisation, the second the open command. So it is vulnerable to replay attacks.”
Lodge also speculated that the lock was made from Zamak, a zinc-based alloy used in products ranging from zippers to rifle buttplates to cheap jewellery. While Zamak’s hard-wearing properties make it good for die-casting, one thing it lacks is tensile strength.
“It took one hit to shear through the connector. Do not use this key box!” advised Lodge, who also made a nine-second video of what happens when you introduce 360lock’s padlock and bike lock to a 1kg lump hammer:
Undoing four exposed screws on the key box led to a blanking plate that Lodge was able to prise off (“it was only held in by silicon sealant”) and gain access to the internal electronics and the motor that drove the lock itself.
“A simple security review would have picked up the BLE replay issue, plus other potential issues. How was this missed?” he asked, concluding: “Lock bodies shouldn’t be made of Zamak and similar alloys. It’s easier and cheaper to cast/machine, compared to steel, but there’s a reason conventional locks use case-hardened metals.”
Security, both physical and digital, is important. Especially so in a smart security product. ®