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Vulnerabilities in TETRA radio networks

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Re: Vulnerabilities in TETRA radio networks

#21
The interview that is linked[0] in the footnotes of the article with the person from ETSI is absolutely wild... Some excerpts:

> kz (interviewer): How did it go about meeting those requirements, because that's the one they're saying has a backdoor in it. Was that the condition for export?

> BM (ETSI): Backdoor can mean a couple of things I think. Something like you'd stop the random number generator being random, for instance. [But] what I think was revealed [by the researchers] was that TEA1 has reduced key-entropy. So is that a backdoor? I don't know. I'm not sure it's what I would describe as a backdoor, nor would the TETRA community I think.

...

> KZ: People ... believe they're getting an 80-bit key and they're not.

> BM: Well it is an 80-bit long key. [But] if it had 80 bits of entropy, it wouldn't be exportable.

...

> kz: You're saying 25 years ago 32 bit would have been secure?

> BM: I think so. I can only assume. Because the people who designed this algorithm didn't confer with what was then EP-TETRA [ETSI Project-TETRA is the name of the working group that oversaw the development of the TETRA standard]. We were just given those algorithms. And the algorithms were designed with some assistance from some government authorities, let me put it that way.

...

> bm: That's what we now know yeah - that it did have a reduced key length.

> KZ: What do you mean we now know? SAGE created this algorithm but the Project-TETRA people did not know it had a reduced key?

> BM: That's correct. Not before it was delivered. Once the software had been delivered to them under the confidential understanding, that's the time at which they [would have known].

...

You've really got to wonder who at ETSI gave the thumbs up on doing this interview.

0 - https://www.zetter-zeroday.com/p/interview-with-the-etsi-sta...

Re: Vulnerabilities in TETRA radio networks

#22

> The vulnerabilities were discovered during the course of 2020, and were reported to the NCSC in the Netherlands in December of that year. It was decided to hold off public disclosure until July 2023, to give emergency services and equipment suppliers the ability to patch the equipment. Interesting discussion about responsible disclosure. It seems a strange belief that you can tell all the radio operators about the…

> It seems a strange belief that you can tell all the radio operators about the vulnerability without also telling exploiters

I suspect that there was an update (or replacement) to the radios that was generally described as an ordinary update / maintenance.

Re: Vulnerabilities in TETRA radio networks

#23
post #14

What exactly were TETRA radios used for? I assume they were government/infra related, but then I don't understand why they'd need to backdoor the keying

They are used for many things, like fire, ambulance, railways, harbour operations, police, military, coast guard, and so on.

The weaker cipher mode, TEA1, is used when selling the radios to anyone who may not necessarily be an ally or highly trusted. This is the legacy of strong crypto being export-controlled.

It was public that these ciphers were weaker, but they were actually much weaker than advertised. This is the backdoor.

Re: Vulnerabilities in TETRA radio networks

#24
Some time ago there was a github repo online that has all teaX and hurdle algorithms code, and also ta61 identity encryption algorithm mentioned by Midnightblue. https://web.archive.org/web/20230213001503/https://github.co...

https://web.archive.org/web/20230213001335/https://github.co...

Re: Vulnerabilities in TETRA radio networks

#25
post #15
post #14

What exactly were TETRA radios used for? I assume they were government/infra related, but then I don't understand why they'd need to backdoor the keying

They don't so much backdoor the keying as that they have 4 different cipher profiles, and the one approved for global rather than European use (TEA1) compresses the key from 80 to 32 bits. It's essentially a surreptitious version of what the US did in the 1990s with "export ciphers".

Which makes me question describing this as a "deliberate backdoor."

Re: Vulnerabilities in TETRA radio networks

#26
post #18

The newsworthy item here is that this is an intentional backdoor. The wikipedia pages list the specific uses per country and department. https://en.wikipedia.org/wiki/Terrestrial_Trunked_Radio#Usag...

Do you remember when cryptography export was controlled? It was implemented by limiting key size to certain number of (effective) bits (of security). This suite is just a victim of that law, as it is a 1990s design.

Re: Vulnerabilities in TETRA radio networks

#27

The interview that is linked[0] in the footnotes of the article with the person from ETSI is absolutely wild... Some excerpts: > kz (interviewer): How did it go about meeting those requirements, because that's the one they're saying has a backdoor in it. Was that the condition for export? > BM (ETSI): Backdoor can mean a couple of things I think. Something like you'd stop the random number generator being random, for…

[deleted]

Re: Vulnerabilities in TETRA radio networks

#28
post #4

Sounds like they took the "roll your own and don't tell anyone how it works" approach. Security by obscurity is never security. History has shown that the open encryption standards are the most secure.

Security has many layers. Obscurity can be one of them.

Re: Vulnerabilities in TETRA radio networks

#29
> Two of the vulnerabilities are deemed critical. One of them appears to be an intentional backdoor [...] Reading the contents of a firmware upgrade is not trivial though, as it is heavily encrypted and relies on a Trusted Execution Environment (TEE), embedded in the core processor of the radio.*

I don't know whether the backdoor allegation is correct, but unfortunately we should treat opaque ostensible security with skepticism.

By their nature, such things often can be used for our protection at the same time they are secretly used against us.

Re: Vulnerabilities in TETRA radio networks

#30
post #26
post #18

The newsworthy item here is that this is an intentional backdoor. The wikipedia pages list the specific uses per country and department. https://en.wikipedia.org/wiki/Terrestrial_Trunked_Radio#Usag...

Do you remember when cryptography export was controlled? It was implemented by limiting key size to certain number of (effective) bits (of security). This suite is just a victim of that law, as it is a 1990s design.

And when people were saying it was a stupid thing? This is one of the many examples that prove it.
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