How Pen Testing Helped to Save My Life
Alright, thats a pretty dramatic title! Here's how my background in penetration testing helped to keep me safe during an amateur project I took on recently
It was time to replace an in-sink disposal but while getting into the project I noticed that there had been some damage to the outlet. Being tucked out of sight under the kitchen sink, I wasn't sure how long the issue had been there for, but now that I knew about it I wanted to get it taken care of.
While very far from a professional electrician, I was comfortable taking this on and I knew enough to cut all the power to the outlet before doing any work. Inspecting the circuit breakers however, I was surprised to find four separate circuits feeding into the kitchen. There was one for the refrigerator, one for the oven, one for small appliances and a final circuit for the microwave and basically the entire main floor. Not wanting to interrupt more electricity than needed, I was trying to be as surgical as possible.
It is easy to see from the blue and yellow circles above that there was some current arcing over time across the faceplate of this outlet leading to some melting. Having turned off 3/4 of the breakers, but not being totally confident I had found the right one, I had the thought to grab the multimeter and test my assumptions. As a pentester, I learned many times the value of not making assumptions. It is a special kind of humiliating to make an assumption on a pentest report that turns out to be not true...besides, maybe there were more than four circuits for the kitchen and they weren't properly labeled in the breaker box!
I set one probe to the expected ground, and the other probe to one of the outlet terminals and if you can imagine what fireworks are like in a cabinet, right in front of your face, you have a pretty good idea of my experience. The tip of the multimeter exploded! Needless to say I needed to turn off the other breaker. This was pretty jarring and I was happy I tested my assumptions first and that it wasn't a hand touching that dangerous outlet. My best, pretty uneducated guess is that outlet was damaged to the point that one of the 120v lines had been bridged into that part of the plate I had expected to be grounded, which led to two hot lines coming together when I ran the test.
This experience reminded me of the importance of knowing how to accurately check my assumptions. It is easy to see how dangerous it can be to be out of ones depth, luckily I knew enough to be careful and double check myself, and this is a skill pen testing helped me to hone. It helped keep me safe in this case. But if ever in doubt, contact a professional!