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New 25 GPU Monster Devours Passwords In Seconds

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Re: New 25 GPU Monster Devours Passwords In Seconds

#21

Post by ErrantX »

peteretep wrote: post #8

The numbers are ... misleading ... and choosing NTLM hashes seems like bordering on misinformation. Taking SHA-1 (which YOU MUST NOT USE for password hashing blah), it manages 63 billion a second. To try all the passwords for that in the alphanumeric space: - 10 chars: 35 weeks - 11 chars: 44 years - 12 chars: 2,800 years - 16 chars: 11 times the age of the sun 10 chars for bcrypt: 600,000 years... http://www.wolfram…

Absolutely; NTLM has been attackable for ages. Running on a Quad core machine it can be cracked in a reasonable amount of time.

The cost/time trade-off for such cracking makes this rig pointless for such cracking, unless you absolutely must have it in 6 minutes.

I don't see any other major use for this; it's simply not powerful enough to attack anything new (Edit: even with 128, rather than 25, GPU's).

Re: New 25 GPU Monster Devours Passwords In Seconds

#22

Post by _b8r0 »

The problem with all of this is that security specialists (of which I am one, guilty as charged) have historically campaigned for more complex passwords. This worked well for conventional (non-clustered, non-accelerated) password cracking mechanisms.

Sadly, this starts to fall apart with accelerated and/or distributed cracking. On average I crack a few hundred passwords a week, and more often than not organisations have what I call seed words (e.g. the password reset word or common words used throughout the organisation) and the majority of passwords are variants of them.

My own ability to crack passwords for most algorithms (within a reasonable timeframe) tends to cap at dictionary words with number and letter substitution and somewhere around the 8-10 character mark. Using a phrase means that as an attacker you have to account for other people using more complex but shorter passwords. I'd still suggest getting capitalisation, punctuation or at least a number in your phrase but the bulk of the keyspace comes from the length rather than complexity plus the fact that the people carrying out these attacks are normally cracking more than one password at a time.

For a few years now (since around the time of Oeschlin's paper[1]) I've been advising customers to use longer passwords made of phrases and things they can remember for passwords they regularly use[2] and randomly generated passwords of some length stored in a password safe[3] for things they might forget. The goal of this advice is to make it harder for people to crack passwords and to reduce the volume of passwords people have to remember.

[1] - http://lasec.epfl.ch/pub/lasec/doc/oech03.pdf

[2] - http://xkcd.com/936/

[3] - http://keepass.info/ - one of many options available

Re: New 25 GPU Monster Devours Passwords In Seconds

#23

Post by raverbashing »

alexkus wrote: post #18
rorrr wrote: post #14

> That renders even the most secure password vulnerable to compute-intensive brute force No it doesn't. My passwords are 30-character randomly generated and look like this: T7PN2m7Yju43IWtoBkwL6TLx18Rdyq Do you want to guess how long it will take to bruteforce with that "monster"? (26 + 26 + 10)^30 = 5.91 × 10^53 possible combinations At 348 billion guesses per second it will take 1.53 × 10^42 seconds or 4.84 × 10^34…

True, but in reality you're probably sending that password over something less secure (like an SSL connection) that doesn't require quite as long (but still a very long time) to crack. Anything is only as secure as the weakest link in the chain. If (I'm sure you don't) you allow your browser to save that password so that you don't have to enter it every time then you just need one cleverly designed trojan to be run o…

There you go

30 chars password don't matter. Sure, it's not low hanging fruit, but it's not troublesome if you're the target

Why?

Weakness 1: Because it's written down somewhere. Weakness 2..n: weaker links in the chain

Re: New 25 GPU Monster Devours Passwords In Seconds

#24

Post by mrb »

peteretep wrote: post #8

The numbers are ... misleading ... and choosing NTLM hashes seems like bordering on misinformation. Taking SHA-1 (which YOU MUST NOT USE for password hashing blah), it manages 63 billion a second. To try all the passwords for that in the alphanumeric space: - 10 chars: 35 weeks - 11 chars: 44 years - 12 chars: 2,800 years - 16 chars: 11 times the age of the sun 10 chars for bcrypt: 600,000 years... http://www.wolfram…

I don't think this is misinformation. You would be surprised at the number of IT people who have no clue how fast NTLM hashes can be brute-forced. Spreading this knowledge is good.

Ranting about NTLM, I am also shocked at how many people are unaware of the pass-the-hash vulnerability enabled by the mere possession of hashes, without having to brute-force them: http://www.youtube.com/watch?v=DkbBCR_vfRQ (disclaimer: I made this video and was a developer for Metasploit/Nexpose).

Re: New 25 GPU Monster Devours Passwords In Seconds

#25

Post by DanBC »

xorgar831 wrote: post #10
mileswu wrote: post #7

Earlier quoted context omitted.

It encrypts all your passwords using AES with a 128 bit key derived from your master password (PBKDF2) [1]. This is very different to what the article is talking about, since it encrypts your passwords, but the article talks about hashing which is one-way. [1] http://help.agilebits.com/1Password3/agile_keychain_design.h...

The problem with PBKDF2 however is that if you pick a weak password it's useless. It would be better if they included an option for a key as well like other password safes do.

> It would be better if they included an option for a key as well like other password safes do.

I would love to see research about the use of keys and passphrases. Especially, do people who have a key then chose a weaker master password?

Re: New 25 GPU Monster Devours Passwords In Seconds

#26

Post by ars »

nakedrobot2 wrote: post #20

I haven't seen the discussion that I think is really necessary - when are we going to move beyond passwords, which are obviously growing more and more obsolete? What are we going to use instead of passwords in the future?

There are 3 types:

What you know.

What you have.

What you are.

And of the 3 What you know (i.e. password) is the most secure when used properly. It's impossible to steal without your knowledge, and it's impossible to misplace.

What you have (eg. physical key) can be stolen from you - or even borrowed, used, and returned without you ever knowing. It can also be copied, and it can be lost - sometimes without being aware of it for a long time.

What you are (eg. fingerprint, iris) is the worst, and the least secure. It's trivial to copy - even from a distance, and it's impossible to change. The entropy available is also low.

So in the future we are still going to use passwords.

Re: New 25 GPU Monster Devours Passwords In Seconds

#28

Post by rorrr »

alexkus wrote: post #18
rorrr wrote: post #14

> That renders even the most secure password vulnerable to compute-intensive brute force No it doesn't. My passwords are 30-character randomly generated and look like this: T7PN2m7Yju43IWtoBkwL6TLx18Rdyq Do you want to guess how long it will take to bruteforce with that "monster"? (26 + 26 + 10)^30 = 5.91 × 10^53 possible combinations At 348 billion guesses per second it will take 1.53 × 10^42 seconds or 4.84 × 10^34…

True, but in reality you're probably sending that password over something less secure (like an SSL connection) that doesn't require quite as long (but still a very long time) to crack. Anything is only as secure as the weakest link in the chain. If (I'm sure you don't) you allow your browser to save that password so that you don't have to enter it every time then you just need one cleverly designed trojan to be run o…

> The National Institute of Standards and Technology (NIST) has issued a statement that says SSL certificates with a key length of 1,024 bits or fewer will be insufficient for security after December 31, 2010

> It is recommended that the algorithms and key sizes in the "Through 2030" row (e.g., 2048-bit RSA) should be used to provide the cryptographic protection

http://csrc.nist.gov/publications/nistpubs/800-57/sp800-57-P...

1024 bit is impossible to bruteforce. Simply incrementing an integer 2^1024 times will take more energy than our whole universe has.

Heck, even 128 bit would take 3.1×10^19 years to bruteforce with that GPU setup. My citibank.com uses a 256-bit connection.

SSL is not "less secure" than my 30-character password (correction: 128-bit one is a bit less secure, but 256-bit one is much more secure).

If it were, all the banks would be freaking out and would shut down their web interfaces.

Re: New 25 GPU Monster Devours Passwords In Seconds

#29

Post by DanBC »

mrb wrote: post #24
peteretep wrote: post #8

The numbers are ... misleading ... and choosing NTLM hashes seems like bordering on misinformation. Taking SHA-1 (which YOU MUST NOT USE for password hashing blah), it manages 63 billion a second. To try all the passwords for that in the alphanumeric space: - 10 chars: 35 weeks - 11 chars: 44 years - 12 chars: 2,800 years - 16 chars: 11 times the age of the sun 10 chars for bcrypt: 600,000 years... http://www.wolfram…

I don't think this is misinformation. You would be surprised at the number of IT people who have no clue how fast NTLM hashes can be brute-forced. Spreading this knowledge is good. Ranting about NTLM, I am also shocked at how many people are unaware of the pass-the-hash vulnerability enabled by the mere possession of hashes, without having to brute-force them: http://www.youtube.com/watch?v=DkbBCR_vfRQ (disclaimer: I…

> I don't think this is misinformation. You would be surprised at the number of IT people who have no clue how fast NTLM hashes can be brute-forced. Spreading this knowledge is good.

That's just depressing, considering how long this has been a problem.

Advice has been, for many years, to avoid using passwords 14 chars or less to force use of NTLMv2.

Here's a Microsoft document from 2004: (http://www.windowsecurity.com/articles/Protect-Weak-Authenti...)

> You would be surprised at the number of IT people who have no clue [...]

No, you're right. It's widespread lack of knowledge, and letting people know that some stuff is not secure, and other stuff is more secure if you have a complex passphrase, is important.

Re: New 25 GPU Monster Devours Passwords In Seconds

#30

Post by Fixnum »

RenierZA wrote: post #27

Can someone please explain why GPUs are so much better at brute force than CPUs? Do they have better instructions/pipelines for the math needed? Why are these not useful/implemented in general CPUs?

Roughly speaking, CPUs are highly optimized for sequential execution, with long pipelines, high power consumption, and complex implementations of arithmetic/logic instructions (I'm not an expert, but I _believe_ these are much _better_ than on GPUs, except possibly for certain graphics-related GPU primitives), but relatively few threads. GPUs are optimized for parallel execution, and run many more threads than CPUs, each with higher latency, but nonetheless with higher overall throughput.
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