Can anyone argue against this being the least-secure hotel room lock on the market? Regular readers will recognize it as an Onity key card lock. A few months back a glaring flaw in the security was exposed that allows these locks to be opened electronically in less than a second. So we are not surprised to hear that a series of hotel room robberies in Houston are suspected to have been performed using this technique.

The image above is from a demonstration video we saw back in October. That hack used an Arduino-compatible chip inside of a dry erase marker as an end-run around the lock’s electronics. It reinforced the warning sound by [Cody Brocious] when he presented the exploit at this year’s Blackhat conference. The barrel jack on the outside of the door lock doubles as a 1-wire communications port and that is how an attacker can gain access. Investigators can find no other means of entry for these thefts.

We applaud one of the victims in this story. At the end of the article she is asked if the information about the Onity flaw should have been kept secret. She said that if there’s a vulnerability that’s not being fixed people have a right to know about it. Bravo [Janet Wolf]!

[Thanks Andrew]

If you’re carrying around an exposed circuit board and a bunch of wires people are going to notice you. But a dry erase marker won’t turn any heads. And this one holds its own little secret. It acts as a master key for hotel room door locks.

This is really more of a repackaging hack. The exploit is already quite well-known. The Onity brand of key card locks most commonly used in hotels have a power jack on the bottom that doubles as a 1-wire communications port. The first published proof of concept used an Arduino board and a simple adapter to unlock any door in under one second. Now that hardware has been reduced in size so that it fits in the hollow shell of a dry erase marker. Even better, the felt tip has been replaced with the appropriately sized barrel jack. Check out the ultra-fast and inconspicuous use of it after the break. We think using this is no more obvious than actually having the key card.