Ring of the Devil electric lock exploit


[Barry] got his hands on an interesting electronic lock pick. The ‘Ring of the Devil’ is made of aluminum and has four magnets inside. By rotating it against an electric lock, (like the one in our RGB keypad lock How-To) the magnetic force can cause the electric motor inside the lock to turn and unlock. More details and commentary are on [Barry]‘s site.

Comments

  1. Ryan says:

    The software update could eliminate some of the threat of this attack. However, only if the lock’s controller is still receiving power.

    Without more detailed descriptions of how this lock operates, I assume that the software update would be able to detect this attack by sensing the current generated from the “the ring of the devil”, log that event, and then apply current in the reverse direction to keep the motor from turning. If power was removed (by a determined individual), the attack would still work. If backup power was battery supplied, it is still possible to use the attack long enough to drain the battery to the point where the ring would overpower the controller. However, if the security system is still active, the cops will show up before you can drain it far enough.

    I wonder if it also has a solenoid to prevent the motor from turning in the event of an attack?

    Another possibility is that if you apply a magnetic field intense enough, the motor’s windings may eventually overheat, short circuit, and disable the controller. The magnets inside of the motor would still respond to the external magnetic field and the lock would open.

    Anybody interested in creating a more complicated “ring of the devil”? One could create a toroid (doughnut shape) with multiple windings and then attach a controller to apply current to the coils in a “rotating” manner. This could be made powerful enough to probably overpower the lock controller’s reverse “anti-attack” current. At the very least it would be faster way of draining the backup battery. It would also be silent and less conspicuous than a power drill. Battery and controller in your pockets, toroid in your hand, and a long sleeve shirt to conceal the wires.

    Then there’s the issue of how the security system communicates with the lock. If wirelessly and with a battery backup, metal bracelets are a sure thing. If the lock is in the door frame with a battery backup and secure shielding of the wires, metal bracelets are in your near future unless you can detect the communication frequency and jam it and the lock doesn’t continuously communicate with the security system. If wired with a battery back up, then the placement of the wires or contacts inbetween the door and frame would be critical, but could still be suceptible if the lock doesn’t continuously communicate with the security system.

    Anyway, I should probably get back to my electrical engineering homework. Thanks for reading my two cents. Ryan

  2. Ryan says:

    O.K., I’m procrastinating from my homework. This attack could be rendered completely useless if the lock’s motor consisted of two sets of coils instead of coils and permanent magnets like all conventional electric motors. Ryan

  3. All conventional? I’d just use an ac motor.

  4. Ryan says:

    Sorry, not “all” conventional, but most small DC powered ones.

  5. Retroplayer says:

    Furthermore, all that would be needed is to “brake” the motor. This means shorting out the positive and negative inputs when the motor is “locked.” The electricity generated by rotating the motor will go right back in to the motor to oppose it. The harder you turn it, the harder it opposes.

    If relays are used to do the braking, there wouldn’t even be any harm of pumping electricity back into the controller.

    Seriously, any good lock should be doing this anyway.

  6. Eltro says:

    hhmm- what if the motor drives a gear which drives the lock? so the magnet would rotate the motor but the gear wouldn’t be in the right position so it wouldn’t, srsly if you want to break in just use a small emp :/

  7. rob says:

    What are you like on sonic screwdriver theory
    ,now that’s an interesting one.

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