Break Me If You Can: Exploiting PKO and Relay Attacks in 3DES/AES NFC

Posted by noproto 7 hours ago

Counter39Comment32OpenOriginal

Comments

Comment by redbell 3 hours ago

> Break Me If You Can

This, somehow, triggered my mind to recall LifeLock's CEO Todd Davis’s public marketing campaign where he displayed his Social Security number on the company website and advertisements to demonstrate the security of his platform, however, the challenge backfired dramatically and he becomes a victim of identity theft on at least 13 separate occasions.

Comment by arkwin 6 hours ago

Looks awesome! I see some Flipper Zero apps were already created. When will you be releasing this for the Chameleon? Also, any plans to port this over to the Proxmark?

Comment by noproto 5 hours ago

All of the attacks are released for the three platforms (Proxmark3, Flipper Zero, and Chameleon Ultra). Our goal was day 1 support for RFID testing devices.

Comment by 1970-01-01 6 hours ago

3DES has been broken for a decade. Nice job putting it all together though.

Comment by moribvndvs 4 hours ago

> Is this a flaw in the cryptography itself? No. The underlying cryptographic algorithms (3DES and AES-128) remain secure. The vulnerabilities arise from:

Protocol design choices that allow unauthenticated memory writes after initial authentication Lack of atomicity when writing cryptographic keys across multiple memory pages Widespread misconfiguration in real-world deployments (unlocked memory, static keys) Non-NXP compatible chips with severely flawed random number generators

Comment by tptacek 5 hours ago

It has? What exactly do you mean by that?

Comment by gjurhgd 3 hours ago

Surely someone who has been here as long as you have understands that this type of behavior is not compatible with the guidelines.

> Converse curiously; don't cross-examine.

You could have just corrected them and not goaded them into further revealing their ignorance. Yes, they underestimated how difficult it is to crack 3DES. You could have simply told them that.

Comment by tptacek 2 hours ago

I have no idea who they are or what they were talking about. I think they're thinking about 3DES used as a password hash. I never in 100 years would have guessed that's where they were coming from.

The thread that ensued, a discussion of what it means for a cipher to be obsoleted or unsafe versus "broken", is an actually-interesting question.

I feel pretty OK about how this went.

Comment by gjurhgd 2 hours ago

You could never, in a million years, have guessed by "broken" they meant "it can be decrypted by the public with little effort?" I doubt that. I see no evidence they are talking about a password hash. Here's what they actually cited:

> The DES and Triple DES ciphers, as used in the TLS, SSH, and IPSec protocols and other protocols and products, ...

They're clearly talking about it's use as a cipher. Again, someone who has been here as long as you have should understand that you shouldn't put words in their mouth or be evasive in this way.

The conversation would still have touched on these interesting topics, and would likely have done so more immediately.

Comment by tptacek 1 hour ago

Do we have conflicting premises about what Hashcat is? I'm pretty sure you're just wrong here.

Comment by zxcvasd 2 hours ago

this is a very common pattern in tptacek's comments, but it's not worth calling out as he absolutely refuses to recognize it, always falling back to a similar response you see here.

with a quick google of "3des broken" and reading the first paragraph of wikipedia on 3des, i was able to guess (correctly!) what they original commenter was referring to.

Comment by tptacek 34 minutes ago

It's pretty self-indulgent of me to respond to this comment, but just real quick: the pattern you're seeing is me in fact not being one of the top-tier experts in cryptography on Hacker News (just one of the loudest), and not knowing who this person is, and not having had a reason to think about 3DES in quite a long time. What you're reading as snark or lawyering is, rather, me meaning exactly what I said, and being uncertain about what that person was talking about.

Comment by 1970-01-01 4 hours ago

It means you should not use it for anything important, because it can be decrypted by the public with little effort. If you look back, it has been this way for quite awhile. My gripe is with the clickbait title 'Break Me If You Can'

https://nvd.nist.gov/vuln/detail/cve-2016-2183

Comment by tostrstrudel 4 hours ago

BREAKMEIFYOUCAN! is the default factory key programmed into every MIFARE Ultralight C chip by NXP.

Comment by 1970-01-01 3 hours ago

Ok that makes much more sense.

Comment by tptacek 4 hours ago

How exactly would you decrypt a 3DES ciphertext "with little effort"?

Comment by 1970-01-01 3 hours ago

It's supported in hashcat

Comment by some_furry 3 hours ago

Is this a bit?

Comment by 1970-01-01 3 hours ago

Have you tried it?

Comment by some_furry 2 hours ago

We're talking about symmetric ciphers and you're talking about password cracking software.

Triple-DES has 168 bit keys. Even if you use a meet-in-the-middle attack, your attack cost has an exponent of 112 (with an associated memory cost with an exponent of 88).

That's not practically exploitable today.

If you think I'm wrong, here's a single block message encrypted with 3DES, then hex-encoded. Have fun:

  924db449f52ea976
But really, the bigger problem is Sweet32.

Comment by zxcvasd 5 hours ago

if i were to guess, they are referring to CVE-2016-2183, which lead to deprecation of 3DES by NIST in 2019 (announced in 2017) and disallowing all uses in 2023. openssl also stopped including it in default builds starting in 2016 because it is considered weak.

Comment by tptacek 5 hours ago

This is Sweet32, an attack on any block cipher with an 8-byte block size. We don't consider those ciphers "broken"; they just can't be used safely in some common modes. You shouldn't use 3DES or IDEA or Blowfish, of course, but I don't think they're considered "broken", not in the same sense that, say, RC4 is.

Comment by tialaramex 4 hours ago

It's true that 64 bits was known not to be enough when DES shipped decades ago, but there is some difference between "We know that's a bad idea" and a demo showing why, and so I think I'm OK with the word "broken" in that context.

There's a reason POCs matter right? Why you feel comfortable (even though I don't agree) saying multi-threaded Go doesn't have a memory safety problem and yet you wouldn't feel comfortable making the same claim for C++.

Comment by fc417fc802 4 hours ago

I'm not a cryptographer but to me "broken" seems to imply that the core algorithm itself can be attacked. If merely applying it in certain ways as part of some larger system can fail then aren't most (possibly all) ciphers broken? It's entirely possible to do all sorts of stupid things.

Granted, a 2^32 block limit is pretty severe by modern standards.

Comment by upofadown 1 hour ago

Si (2^32)*8 works out to 34GB for TDES. How many applications involve encrypting that much data in one go?

Comment by tptacek 4 hours ago

This semantic argument was more plausible before the original commenter claimed 3DES can be "broken with little effort".

Comment by tialaramex 3 hours ago

That's fair, I won't defend "broken with little effort".

Comment by _tk_ 3 hours ago

Not to be rude, but it seems to me that you are engaging in some hairsplitting. In general, security people do not recommend to use 3DES or RC4 - even if RC4 is broken in other ways than 3DES.

Comment by tptacek 3 hours ago

RC4 is actually broken. It's fundamentally broken. As you run it, it's face melts off like the guy at the end of Raiders. It's genuinely weird nobody noticed how bad it was, in a practical sense, until the late aughts.

The 64 bit block size in 3DES (and Blowfish and IDEA) limits how much data you can encrypt under a single key. I think the real "tell" that this isn't hair-splitting is that people don't ever generally talk about Blowfish being "broken", just obsoleted.

Comment by _tk_ 3 hours ago

People just don’t talk about Blowfish.

Comment by zxcvasd 5 hours ago

to any non-cryptographer, i think that's a distinction without a difference. it's disallowed from use by the major standards institute due to a vulnerability where people can recover the plain text.

that sounds "broken" to me, but i'm not a cryptographer. so, i'll defer to you when you say it's not broken. (i dont know what the cryptographer-specific definition of broken is -- it'd be great if you would shed some light on that)

Comment by tptacek 1 hour ago

Again: not a vulnerability in the cipher.

Comment by zxcvasd 48 minutes ago

[dead]