Transcript for Hacking Hotel Locks in Seconds With Cheap Tools
"World news" getting answers tonight as hotel chains and their guests have a new high tech problem on their hands this ev the swipe cards to get into their room. Here's abc's mark greenblatt.... See More
"World news" getting answers tonight as hotel chains and their guests have a new high tech problem on their hands this ev the swipe cards to get into their room. Here's abc's mark greenblatt. Reporter: Just blocks from times square, tourists trust hotels like the hilton garden inn for a safe night's sleep. But when abc news checked in, we discovered a major security hole. Electronic locks on guest rooms can open without a key. I'm going to insert this marker into the bottom of the door and the door is going to open. Reporter: You are in my room with your hands on my ipad. This security consultant showed us just how easy it is to break in, with a device that costs just $50 to build. I can go down the entire hallway and unlock every single door. Reporter: And it worked at the nearby holiday inn express. Where once again, no key, no problem. Hackers first exposed the problem earlier this summer. Posting videos like this one on youtube. Using more primitive gadgets. Now, the tools can be hidden in magic markers, even iphone cases. And the how-to guide is just a click away online. Big name hotels reportedly bought millions of the faulty locks from a company called onity. I would say millions worldwide are at risk every single day. Until this problem is fixed. Reporter: Onity told abc news the company is working with its customers to deploy solutions. No one seems to have warned the manager at this hilton garden inn. I'm not aware of that. Reporter: You never heard of it? No. Reporter: But after we showed him the video -- I will be happy to bring this to hilton's attention, because this is a security proem. Reporter: Before we could follow up -- he was whisked away. What will you do about this? A spokesman for hilton worldwide later told us the whole company is investigating and addressing the problem. And in a major announcement, holiday inn's corporate office has advised its hotels to try to expedite delivery of a product that will block the hack. The holiday inn express in times square has placed its order
This transcript has been automatically generated and may not be 100% accurate.