That Time I Accidentally Hacked My Neighbour

Working from home, I take many meetings. During the meetings, it was apparent I was having networking issues. Calls dropping and people saying my picture was very pixelated. Other participant’s video seemed fine to me, however. During my regular work, I didn’t have many issues. After much sleuthing, I figured out the issue: My work laptop’s internal antenna wasn’t adequate to send the signal through all the walls to the router. The massive antennae on the router were adequate for send the signal to the office, which is why downloads were fine but uploads suffered.

I didn’t really want a massive Ethernet cable running through my apartment, so I picked up a couple of Powerline adapters to network over my apartments electrical wiring. I plugged in the devices and I could surf the Internet. I checked speed tests and got about 40Mbps. Not great, but enough for video calls.

I moved the office Powerline device to another electrical socket and connected a second WiFi router as an Access Point. I had WiFi in my office now. Cool! I tried connecting to my media server, but wasn’t able to. Hmm… I started looking at the networking. The subnet was different from what I expected. I figured it was the new Access Point, so I connected to the web interface of my default route. That’s strange. The management interface looks different. It’s a cable modem interface, but it’s different from the cable modem interface I’m used to. “What the hell am I looking at? Did my modem get reset?” I google the device name for the default login and password. I logged in to the device and look at the LAN/DHCP settings. “Wait. I don’t own a Chromecast.”

It hit me like a thunderbolt: I was looking at my neighbours cable modem through my Powerline adapter.

I quickly noped out of everything and unplugged the Powerline adapters. After more reading, I discovered my mistake. I assumed the devices came pre-paired, however once they are installed you are supposed to push a little button on them to sync them and set up an encrypted channel. I also changed the default “Network name” so there is no way they can connect to my neighbour again, should one of them fail.

The thing that really has me thinking: How was my device was able to connect to my neighbours network? Either my apartment’s electrical wiring has a bridge to their apartment or the device connected across my main fuse panel, out through my power meter, connecting back in through their power meter and across their fuse panel. I am still a bit confused on that bit.