Terry Zink's Cyber Security Blog

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I got locked out of my house this past week. This reminds me a bit of the NSA.

I got locked out of my house this past week. This reminds me a bit of the NSA.

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This post probably contains more information than you wanted to know.


My wife last week was out of town, and during the week we had our windows replaced from single-pane to double-pane. Single-pane windows are very cold in the winter, the heat just gets sucked right out of them.

The window guys came by in the morning on Wednesday. I asked them to do what they needed to do, lock the doors when they leave and just exit out the garage. They just needed to push the garage door opener by the exit when they were done. It’s a bit of a security risk leaving them alone, but I didn’t have much choice because I had to run down into the city later in the day and couldn’t come back in time to see them off.

Well, fast forward to the evening. I came home and everything was intact. About 75% of the windows were replaced, I didn’t notice any issues at all. The cat didn’t enjoy being locked in the bathroom all day but she got over it.

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Later that evening, I took the trash out. I walked out my front door and put the trash in the garbage can and took it to the curb. I walked back from the curb to the front door and press the door handle.

The door wouldn’t open.

“What the—?” I said.

I then used my tried-and-true strategy for getting into locked doors that failed the first time: I tried opening it again. And once again, it wouldn’t open.

“WHAT THE—!” I shouted. How did this door lock?

I have a deadbolt. The only way to lock the door is to physically turn it from the inside, or insert the key into the outside lock and turn it physically. Ergo, it is impossible to lock myself out. I like it that way otherwise I’d lock myself out all the time (something I did a couple of times while I lived in England).

How in the world did I lock myself out? That’s not possible!

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I had no keys, no jacket, no wallet, no phone. All of it was indoors. Furthermore, all the windows had just been replaced so I couldn’t break any of them (well, technically, I guess I could have). But the back doors were now secure as they had just been replaced a few hours earlier.

Bottom line: I had no way to get back into my house. And no idea how I got locked out.

I went around the house looking for ways to get in, knowing that I couldn’t. I tried each window and each of the back sliding glass doors. No luck. I tried lifting up the garage door, also without success.

My brain started to race a bit. What was I going to do?

I walked to my neighbor’s place and asked for help. We’ve chatted several times in the past and know each other. I knocked on his door and explained my situation.

I asked to borrow his phone and the first thing I did was call the wife. For you see, there are some friends of her parents who have a spare key, but I can’t remember exactly were they live. I also don’t know their phone number. And even if I did know where they lived, there’s no guarantee they would even be home.

Unfortunately, the wife didn’t answer her phone. I had no other option, I had to call a locksmith.

I waited about 30 minutes at the neighbor’s for the locksmith to arrive. He proceeded to try to pick the lock but it didn’t work. The lock is a newer lock and is resistant to picking. There was no way to get inside short of brute force.

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Fortunately, I had a backup plan. That day I drove to work, but I walked home. On days where I drive, I like to get exercise if I can. At work, I had the garage door opener inside my car. Since the door inside the garage leading to the house was unlocked, as long as I opened the garage, I could get inside the house. And, getting into my car is much easier than getting into the house. Experienced people can into my locked car in under a minute, they’ve done it before, and they did it this time.

We drove to work, got into my car, I retrieved the garage door opener, returned home, I opened the garage, and got inside.

Success!

But why did my front door lock me out? That made no sense!

I inspected further. The deadbolt was not engaged. Instead, the window people when they were locking up flipped a switch on the doorknob. By doing that, the front door handle does not engage by turning the knob when you press down on it. In this mode, it only opens if you have the key to unlock the deadbolt. They flipped this switch earlier and when I closed the door behind me later that evening, I had no way to get back inside since pressing the handle would not actually turn the knob. We never use this setting so I never would have thought to check this.

Anyhow, I paid the locksmith $153 for his time: a service call, labor, and getting into the car. Yeesh.

After I was back inside, I started thinking about how I got back into my house. I didn’t use brute force to break in, and I didn’t pick the lock, either. The lock and structural integrity was in place the entire time. Instead, I used a “weakness” to get into the building.

This reminded me (loosely) of how the NSA “breaks” encryption. Ever since the Snowden story broke, people have been wondering “Does the NSA have a way to break encryption?” The collective seems to be “No, so long as you use the right algorithms. However, the NSA usually goes around the encryption.”

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I’m not sure what that means exactly (I haven’t read up on the finer points), but just as I could have used brute force to break into my house but didn’t, the NSA could use brute force to break encryption but doesn’t (or rather, cannot). But just as I didn’t need to break in, the NSA doesn’t need to break encryption, either. They can go around by getting the encryption keys, getting access to data unencrypted, or just observing patterns.

In other words, what I can do in terms of physical security, professionals can do in terms of cyber security. There are multiple other ways to compromise the perimeter other than doing it in the most obvious way.

Anyhow, that’s what went through my head.

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  • Another lesson is that upgrading Windows, while generally a good idea, can cause unexpected problems.

  • @Martijn: That made me laugh out loud, literally.

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