Cordless Telephones: Bye Bye Privacy (1991) | Hacker News Reader

Cordless Telephones: Bye Bye Privacy (1991)

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43 pointstux9 comments

When I was in high school a friend and I bought a portable scanner from Radio Shack to do exactly this after reading an article about it in 2600.

After getting bored chatting with people on our BBS or hacking around in Turbo C, we'd cruise the suburbs and listen in on phone calls.

We never stopped the car, so it was just a leisurely drift over usually mundane conversations. When you got a handset instead of a base station (or maybe the other way around, I forget), you'd only hear one side of the conversation, and it was fun imagining what the other person was saying.

Magical times.

I may have written that article...mine was published in 1994 ( http://mail.blockyourid.com/~gbpprorg/2600/2600_11-2_Page_18... ). Another one had been printed in 1989, and then another in 1988. I mentioned that Radio Shack had the scanners in my article, but suggested people look around for better bargains.

The 800 MHz radio shack scanners at the time had some kind of daughterboard that blocked scanning cellular frequencies, but there were instructions on the Internet of how to get in there with your soldering gun and dike it out, and get access to that bandwidth. I later learned from a Radio Shack manager the undocumented key punch sequence that bypassed the daughterboard, so you could scan cellular without going through all that trouble.

Removing D18 in the Pro-36 would unblock the 820 MHz AMPS band. Fun times.

Yes, this is indeed the article!

When I was in school at Rose-Hulman, the Dean of Students lived in an apartment attached to one of the dorms (my own dorm, as it happened). He had a teenaged daughter, and at the time, Rose was all-male.

They had a cordless phone.

Some brilliant EE thought it would be a good idea not only to eavesdrop on the daughter, but to put that audio on his stereo at extremely high volume.

The Dean very quickly no longer had a cordless phone, and as I recall (it's been a long time) that student no longer had a place at Rose-Hulman.

Yes but then a few years later cordless phones went digital which made it much harder than just using a scanner and then a couple years after that they went spread-spectrum which made it exponentially harder.

Today's version of this kind of spying on neighbors would be baby monitors.

There are actually lots of DECT phones which don't implement encryption, see e.g: http://www.theregister.co.uk/2008/12/31/dect_hack/

I've tried this with a DECT PCMCIA card, and could snoop maybe half of a stack of handsets I got off trademe. This is a few years ago though.

Back when I was growing up (15-ish years ago) we had an asshole neighbor who used to do this exact thing to another neighbor. I'm not sure how they figured it out, but I know that bank account numbers were involved.

Also see https://www.iacr.org/archive/fse2010/61470001/61470001.pdf

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