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In this article, we’ll examine the security of a typical manually-operated garage-door and a typical electrically-operated garage-door. I will demonstrate major vulnerabilities in each of these systems and show how those vulnerabilities can be easily exploited to unlock the doors. Then we’ll discuss how the security of these doors can be improved by a professional installer.
Manually Operated Door
Figure 1 shows a typical manually-operated garage-door in the process of being broken into. The door has a locking T-handle in its horizontal center. At the back of the handle is a cam. Inside the door, a spring-loaded latch is mounted on the left side and another on the right, each locking to its respective rail. (See the right latch in figure 2.) A single cable attaches the two latches and runs through the handle-cam. When the handle is unlocked with a key and rotated counter-clockwise, it rotates the cam to pull the two latches, releasing the door so it can be lifted.
The biggest problem with this design is that the latch-cable is completely exposed on the inside of the door. This makes it very easy to unlock the door with nothing more than a simple tool fashioned from a metal coat-hanger. That’s what was being done in figure 1.
For a demonstration of the tool in action, see figure 3. The door was lifted slightly to insert the tool under the left side. The hooked inside end of the tool was then lifted and hooked over the top of the cable. As pictured, the tool was then used to pull the cable downward. Since both latches are operated by the same cable, this action retracted both latches, unlocking the door very easily.
The lock-cylinder within the T-handle uses a single-sided key with five cuts. The cylinder contains five simple wafer-tumblers. This is a rather low-security lock-cylinder that can be picked easily by raking. It’s the same with every garage-door handle I’ve seen, whether T-shaped or L-shaped.
Rather than cable-operated spring-latches, I suggest a sliding bolt that securely locks the door to the rail. One such lock is shown in figure 4. Mounted to the door, it does a nice job of securing the hot-rod car in figure 5. If the ability to lock or unlock the door from the outside is not required, this lock is a great choice. There’s no lock-cylinder to pick, and the lock-bolt sticks through the rail about an inch. The bolt is pretty difficult to grab and retract with a coat-hanger, but it has a padlock-shackle hole in the end just in case you’re paranoid.
If it is a requirement that the lock be operable from the outside of the door, then there are similar locks available that can be operated by the tailpiece of a rim-cylinder. I suggest a cylinder with good pick-resistance features, as any lock-cylinder that can be picked by raking should not be considered a high-security lock and is hardly worth installing.
Figure 6 shows typical electrically-operated garage-door on a two-car garage. The door is operated simply by pushing a button mounted on a wall inside the garage, or on a remote inside a car. A motor turns a sprocket that pulls a chain. The chain moves a trolley along a rail. The trolley is connected to the door by a steel arm. It pulls the arm to pull the door open and pushes it to lower the door back down.
The door ordinarily can’t be moved manually, but there is an emergency release-lever in case of power failure. A short red rope is attached to the lever so that people don’t have to reach so high to pull the lever. When the lever is pulled down, either directly or by the rope, the door-arm disengages from the chain-driven trolley. The door can then be lifted manually.
Modern electric garage-door openers can be operated by wireless remotes and are equipped with technology designed to prevent the door from being opened by unauthorized remotes. I presume that the latest garage-door openers effectively mitigate this threat, but the extent to which they do so is a subject of debate. I have not conducted an analysis of the security of radio communications in wireless garage-door systems, so any associated vulnerabilities will not be addressed in this article.