By Cory Doctorow at 4:37 am Mon, Apr 5, 2010
Sliding chain lock, meet rubber band.
Defeating a sliding chain lock using a rubber band
In Singapore for work a couple of years ago the front desk gave my room to another customer in the middle of the night. So I’m standing behind the door wearing what I sleep in (which is what I was born in) and this guy is trying all kinds of tricks on the chain, mainly with paper, not rubber bands though.
It didn’t seem to occur to him that somebody had to be in the room. After a while it got stale so I shut the door.
Having see this video I will be less tolerant in the future. I actually believed they would have to break the chain to get in. Not so.
I travel a lot, and I haven’t seen a chain on a hotel door in quite some time. They’ve generally been replaced with solid swing bar door guards that are more secure. They won’t stop a determined attack, but they’re harder to defeat by either clever tricks or brute force.
And with a few more rubber bands and a shot gun, I can make a simple device that will keep people from getting in.
Well most of them won’t get in.
I saw that in Kill Bill I think…
I concur with paulj, I’ve stayed in too many hotel rooms to count in the past 5 years and I’ve never seen a chain type secondary lock on a hotel door, they’re all the sliding swing bar type. Maybe they’re still common in Europe?
Also, the “chain has been repaired” shot… how do they think the chain was attached to attach point in the first place? It didn’t fall out of some metal forging womb pre-attached. The link had to be soldered together after being fed through the hole in the fixture.
I used this very trick back when I was in school to open my parents patio doors, after forgetting my keys. MacGyver was huge at the time, I guess. I used notepaper to catch and pull the key under the door, then a rubber band to defeat the chain.
Yeah, I could have kicked the door down, but my parents wouldn’t have been happy.
The point of NOT kicking a hotel door down is that if you are doing the sort of thing that requires you to enter a hotel room without a key, then being discrete will buy you more time after the event.
I think mythbusters demonstrated that these little locks could be stronger than they look. The buff-bald-mustache guy rammed the door with his shoulder quite a few times but couldn’t break the chain lock. The catch was they had used long screws to hold it in place in the frame; maybe a standard setup is more vulnerable to kicking/ramming.
But yeah, it wouldn’t take much of a bolt cutter to get through that little chain. If you want to feel safe at a hotel, find one with a surly, scary-looking night auditor.
This is not a new trick. I learned it in high school in the … ummm … early 60s. My method used a piece of tape as well, which helps when the door can’t be opened as wide as this one. You can use the reverse of the method to relatch the chain, adding to the confusion. (Do be careful not to leave fingerprints on the tape, dear.) It can be quieter than in the video, but this is really a technique best suited for an unoccupied room.
By the way, if stealth is not a consideration, the screws on these chain locks are rarely long or strong enough to withstand the shoulder of even a high school girl, and if they are, the screws or nails in the door jamb may give with the persuasion of a well-placed foot.
And they thought I was such a good girl …
I’m not sure exactly why, but I found that hand to be a hilarious actor.
Of course, it’s impossible to affix the rubber band if that little black lever below it is turned, because that’s THE DEADBOLT. No one in their right mind will rely on just the chain. Idiots.
Two words: door knob.
If you want to feel safe at a hotel the bottom knob on the main latch is the deadbolt, and I think you’re pretty secure once you’ve thrown that. I don’t know why they would even have the chain with the card lock/deadbolt combo below.
Honestly, if the person who wants to get into your room is prepared enough, nothing on a hotel door is going to stop them. They won’t even break a sweat doing it.
Most of the master entry keys for a certain lock type are universal…totally universal. Meaning if I buy an entry key for one lock type, I can get into any lock of that type with minimal effort.
If the hotel never even bothered to put the key cylinder in the lock…well…even easier to get past the lock with a simple pair of needle-nose pliers.
As for the chain, you can use the rubberband method above or if your hand is already making it that far in, just unscrew the device from the door frame.
It’s mostly for psychological comfort. Although the “deadbolt” isn’t really a deadbolt–hotel Master key cards can open them. There’s also a special tool to open sliding bar locks from the outside, but it requires a little bit of skill and makes a lot of noise.
This is what happens when Marsellus Wallace sends his IT man to collect on your ass.
I thought the video was neat. Certainly not as a how-to for defeating a high security system, but as an “ah-ha! that’s clever” sort of thing. I think everyone knows these chains aren’t secure, but it’s still fun to see a simple way to open them that’s got a little more finesse than a shoulder to the door.
From years working at a hotel – ours didn’t use these because often management needed emergency access to rooms (injuries, suicide attempts, complaints) so they prefer deadbolts that can be opened from outside with a key.
The hotel room I stayed in on Monday night (Toronto, major chain) had such a lock on the door, although I have noticed they are becoming less common.
Some of the “experts” in this thread piss me off. Hacking for the simple pleasure of hacking isn’t reason enough to enjoy this video?
Handy trick for getting back in the room when your friend’s passed out and you don’t want to be billed for the lock. Pros would be better prepared and would have bent wire with a bungee on it to open the thing, and wouldn’t need to reach a hand through, just the wire.
it seems today was pirate day. with all the chain breaking, door busting and stuff.
the ninja perspective would keep in mind the fact that this approach leaves no traces. as with some bump keys and whatever-method-used to open the hotel door card lock it would be very difficult to prove or notice (for the victim) that there was an actual entry.
yes, there are loads of ways to open doors, some of them quick, some slow.
if you open doors to take pictures of rival companies documents without them knowing, i would still hire a ninja, not a pirate.
The thing is that since the door is the only way in and out of the hotel room. The only way for it to be possible for the chain to be locked is if someone was in the room. So ninjas now have to deal with that. Pirates just wouldn’t care.
Well the point of these devices is not that they’re immune to the ‘shoulder to the door’ attack, etc, but that they’re designed so that it’s ‘impossible’ for someone to put their hand through the gap and unhook the chain and then open the door.
This hack (or should that be crack?) defeats the principle security selling-point of the device with … just a rubber band.
Well if the chain had been installed more correctly then the gap would have been too small for the person to put their whole hand through. You need very little slack in the chain, just enough to make it comfortable to lock. Any more than that and you are allowing someone easier access to try and defeat it.
just because they demonstrated it on a hotel door, does not mean it will only work on a hotel room door. This will come in very handy when my sleeping wife has engaged the sliding chain lock to see what time i come home from the bars.
“I got in at 1030, don’t you remember letting me in? you must have been sleepwalking”
Woah, I think you have more problems there than just a chain lock.
My ex-husband demonstrated this for a few of us 25 years ago. Hysterical, really.
Me’s think this would only work on locks where the chain was a bit long. Or you hand was really thin…
THESE CHAINS ARE PRIVACY DEVICES, NOT SECURITY DEVICES. They’re intended to let one open a door slightly to talk through the crack without making it easy for someone to push their way in or accidentally exposing more of yourself, or your mess, than necessary. However, they will NOT hold against a determined individual even without this finesse solution. The chain, and mounting, are simply inadequate.
If you want a device of this sort which is secure, the proper solution involves chain on the order of bicycle chain, looped around the doorknob or some similarly well-secured anchor point on the door, and lag-bolted into the wall studs rather than held to the door frame with short screws.
Note, too, that whether this rubber-band trick works depends on just how much slack there is in the chain, since it requires being able to reach through the gap.
Summary: Major yawn. Non-surprising attack against a device never intended to withstand an attack and mis-installed to boot. Demonstrates that some folks don’t understand the device’s intent, and that’s worth correcting; otherwise fairly boring, frankly.
(Yes, I’m a part-time locksmith, and yes, this is what I tell customers whenever I see one of these.)
i can’t wait until those lock-picking-aficionados discover the crowbar or sledge
Does not even keep out nice people. I remember we had some friend over and I was sent out to get something from the store. Someone thought it would be funny to put the chain on. I came back carrying groceries opened the door knob and pushed in the door since my hands were only half free. First thing I noticed of the chain being on were the bits of it flying across the room as I entered.
If the chain is short enough to allow the door to be opened wide enough for a hand to slip through, then a piece of string is all that is necessary.
Agreed with Technogeek, the chain show is wrongly installed, the hand can already get far enough around to unhook it. The chain is only designed to deter foot-in-the-door type callers. A small set of bolt cutters would defeat it too, as would a shoulder charge.
I too have been a locksmith, I’d tell customers these only keep nice people out.
“…the hand can already get far enough around to unhook it.”
But there isn’t enough slack in the chain to slide back to the unhook position when the door is open enough for the hand to reach around there. The door needs to be in the closed or almost-closed position for that to happen, hence the need for the rubber band.
For that matter locks only keep nice people out…
As the above commenters, this is a less than elegant solution. As the keycard lock has already been bypassed, bolt cutters aren’t even needed unless quiet is paramount. Thanks to Newton, most people could shoulder or kick through that door with relative ease.
Given how much noise this makes and that someone is already in the room – I think the next hand that comes through the door is going to go back minus a finger or two.
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