They got in by cracking the security on a high-end electronic key-card system
The hack: Researchers at F-Secure, a Finnish cybersecurity company, breached the defenses of a hotel lock system known as Vision by Vingcard last year by combining a card reader that can be bought online for a few hundred euros with custom software. Using old cards from hotels, they generated a master key that gave them access to all the rooms using the lock.
Don’t panic: After they discovered the security flaws, the researchers alerted Assa Abloy, the lock’s Swedish manufacturer, and worked with it to develop a software fix, which was issued earlier this year.
Okay, maybe just a little: Hotel chains need to apply the fix to their systems, so it’s worth checking with your hotel to see if it’s using the cards. Better to be safe than sorry.
Talking of safe(s): The one in your hotel room is there for a reason, and so is the security chain on the door.