3D printed safe-cracking robot impresses at DEF CON 25

3D printing and security research have long history. The lockpicking community and security researchers have made frequent use of 3D printing to draw attention to vulnerabilities and encourage manufacturers to think more about better ways to protect assets.

DEF CON is the “world’s longest running and largest underground hacking conference” and has demonstrated many imaginative uses of 3D printing in this area. The conference recently celebrated 25 years and once again 3D printing took to the stage in Las Vegas.

3D printing was used to make several of the components of the robot, including a nautilus gear that is vital to the device’s operation.

Some of the 3D printed components of the SparkFun Safe Cracking Robot. Image via SparkFun.
Some of the 3D printed components of the SparkFun Safe Cracking Robot. Image via SparkFun.

Best present ever

Nate Seidle is the founder of SparkFun, an electronics retailer in Niwot, Colorado. Seidle’s company sells electronic prototyping platforms – such as the Arduino and Raspberry Pi – alongside 3D printers. Using an Arduino, a servo motor and several other components Seidle built a safe-cracking robot together with Rob Reynolds and Joel Bartlett who also work at SparkFun.

The project wasn’t part of a criminal enterprise. Rather Seidle’s wife had given him an unusual Christmas present, a fire safe. As he explains, “It was super cheap because the seller didn’t have the combination. Best present ever.”

To open the safe Seidel built an “Autodialer” style brute force robot. “Instead of attempting every combination in the solution domain (called brute forcing), we use some tricks to reduce the domain and shortcuts to speed up the testing process. In addition, the SparkFun Safe Cracker is cheap (~$200), magnetically adheres to the safe, and is non-destructive; when we’re done you’ll never know we were there.”

3D printing was used to make several parts. Image via SparkFun.
3D printing was used to make several parts. Image via SparkFun.

Getting cracking

The model of safe chosen for the latest demonstration – the SentrySafe – has three rotors. Each of these rotors has 100 potential positions, this means that a total of 1 million individual combinations are possible. While Seidel’s robot could work through each of these combinations, to do so would take months. The latest iteration of the safe cracking robot is able to decrease the possible amount of combination numbers from 1 million to 1,000.

To achieve this Seidel delved more closely into the inner workings of the safe. He found that the by disassembling the SentrySafe and measuring the dimensions of the notches on the rotors he could use this information to speed up the process significantly. Prior to DEFCON 25 the SparkFun Safe Cracker was taking just over an hour and a half to open a safe.

Rising to the challenge of the DEF CON conference the SparkFun team were able to open the safe in approximately 30 minutes. Jokingly the team told reporters that they could have done it faster, but they had to fill their 45 minute presentation slot.

The SparkFun team opening a safe at DEF CON.
The SparkFun team opening a safe at DEF CON.

Of course there are concerns about how such a tool could be used in a malicious manner. This is something Seidle counters by saying, “We believe knowledge and education is the best protection against fear and tyranny. The SparkFun Safe Cracker is designed to open very low security combination fire safes. There are high-end, secure, expensive combination safes available that have the ability to detect and thwart this type of dialer attack. Or, you could use a keypad safe.”

You can see the full slide deck from DEF CON 25 here. If you want to read more about the SparkFun Safe Cracking Robot Siedle has a handy how-to guide on his website.

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