How to eavesrop on cordless phone?

[compaq]

If you have a scanner and you can decode DTMF, which is digtal, can you use a scanner plugged into a computer that can record and crack digtal encrpytion in real time, or would it be delayed?

[Thorn]

If you have a scanner and you can decode DTMF, which is digtal, can you use a scanner plugged into a computer that can record and crack digtal encrpytion in real time, or would it be delayed?

A couple of things:

1) It's spelled "digital". There are excellent spell-check programs available for most browsers.

2) Dual-Tone Multi-Frequency (DTMF) is NOT digital. DTMF is comprised of two analog tones, superimposed over each other.

In theory, any encryption can be cracked if you have a have some part of the message that is known, or you can reasonably guessed to be in the message. However, there are practical limits to this.

A scanner would be pretty impractical for this application, however, as would using a computer. That would decidedly cause a delay and would not be real time. There are at least two ways to do this cheaper and easier, and in real time.

Of course, this begs the question: "What part of 'illegal wiretap' don't you understand?"

[robertltux]

just to be clear any operation that involves tapping either the Public Switched Network or decryption of scrambled radio signals can and will get you a Visit By a few different TLAs and Ghod help you if you happen to trap a DO? /SS communication (plane ticket to Cuba anyone??).


Heck some folks round here may just track you down to save themselves the grief.

[compaq]

just to be clear any operation that involves tapping either the Public Switched Network or decryption of scrambled radio signals can and will get you a Visit By a few different TLAs and Ghod help you if you happen to trap a DO? /SS communication (plane ticket to Cuba anyone??).

Hence the reason why I don't listen into any radio channel that is not public.
But if I get a digital phone and a scanner/computer to listen into my own music playing over the phone, as far as I know that isn't illegal, and I don't think talking about it, even to the point of asking if its doable with cheap hardware is.

2) Dual-Tone Multi-Frequency (DTMF) is NOT digital. DTMF is comprised of two analog tones, superimposed over each other.

I was a bit confused, I read that along time ago, but when I looked on screen of a recorded voice which had DTMF they looked digital(square like). Is that becuase it just repeated the freq quickly a couple of times?

[Thorn]

Hence the reason why I don't listen into any radio channel that is not public.
But if I get a digital phone and a scanner/computer to listen into my own music playing over the phone, as far as I know that isn't illegal, and I don't think talking about it, even to the point of asking if its doable with cheap hardware is.

No, that wouldn't be illegal, although I really doubt that a phone system has the proper audio frequency range. Most phones tend to flatten in the middle the audio ranges to make voices clearer and minimize audio interference. The same goes for the scanner receive audio. Also, I doubt the transmit duty cycle is rated for a long length of time.

All-in-all, you'd be better off buying one of those cheap FM transmitters designed for use with an MP3 player.

I was a bit confused, I read that along time ago, but when I looked on screen of a recorded voice which had DTMF they looked digital(square like). Is that becuase it just repeated the freq quickly a couple of times?

It may have been a square wave approximating the actual wave. That is fairly common with newer mass-produced phones. It may have also have been chopped due to the limitations or settings of the equipment being used.

[Buddy61]

What about IT security folks listening to VOIP conversations over a network? and by the way since we are correcting spelling errors, the correct spelling for God is God NOT Ghod???

[Thorn]

What about IT security folks listening to VOIP conversations over a network?

That depends on exactly the way the wiretap law is written for the jurisdiction, and where the tap is performed. For instance, the FCC has said that in the US, if the conversation is carried anywhere on the public switched telephone network, then US federal wiretap laws apply. So a pure IP-to-IP conversation (e.g. Skype) could be legally listened to on an IP network, but it would be illegal to listen to a conversation on a system like Vonage -which uses the public switched network for part of the transmissions- without a wiretap warrant.

and by the way since we are correcting spelling errors, the correct spelling for God is God NOT Ghod???

Actually, it's "god". It's only capitalized by the irrational and superstitious.

[softwaredefinesradio]

I was wondering, how easy/hard would it be for someone to eavesdrop on a cordless phone conversation. For example, I wanted to try this out to my own cordless phone, a panasonic one which uses GFSK and is not employing any kind of security (DSS for example). I have all the technical specs that may be required, but how would one go about on doing something like this?

Booklet,


Try doing a google search on dedected.

Then google search the following:

Security of Digital Enhanced Cordless Telecommunication (DECT) devices for residential use

A diploma thesis written by Alexandra Mengele is now finished and available for download.

The thesis contains test results from a lot of consumer phones and a detailed explanation
how these phones where tested. It also summarizes most of the attacks on DECT which are
currently known.

I've read through it and it shows everything there is about Cordeless DECT telephones.

A excellent read indeed!

Hope this helps you.

SoftwareDefinesRadio

[Barry]

Actually, it's "god". It's only capitalized by the irrational and superstitious.

Hahahahahahahahaha!!


Also to ad to the IT listening to your VOIP conversations, if the tap is in place inside the corporate network/phone infrastructure I'm pretty sure they're legal.

[Gitsnik]

Also to ad to the IT listening to your VOIP conversations, if the tap is in place inside the corporate network/phone infrastructure I'm pretty sure they're legal.

I'm hoping lupin reads this and corrects me if I'm wrong, but as I understand it (at least here in .au), any snooping of this nature without warning both parties without a warrant is a felony and can be prosecuted (it would be a rare thing for it to happen though, unless the admin was someone like me who made a little extra off the side keeping secrets). The same applies to spam filtering (technically any content based filtering breaches Australian Federal Mail tampering laws (mail is a federal crime, but murder is a state crime lol).

It has never stopped me placing content filters or network taps at the appropriate locations, and logging people who the CEO finds... interesting... in case they have to be let go on short notice, but if anyone had caught on and decided to prosecute* then there could well have been a court case on my hands.

*they would have found zero logs and zero evidence and pristine servers