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Cheap GPUs Rendering Strong Passwords Useless
StrongGlad writes with a story at ZDNet describing how it's getting easier to use GPU processing against passwords once considered quite strong.
"Take a cheap GPU (like the Radeon HD 5770) and the free GPU-powered password busting tool called 'ighashgpu' and you have yourself a lean, mean password busting machine. How lean and mean? Working against NTLM login passwords, a password of 'fjR8n' can be broken on the CPU in 24 seconds, at a rate of 9.8 million password guesses per second. On the GPU, it takes less than a second at a rate of 3.3 billion passwords per second. Increase the password to 6 characters (pYDbL6), and the CPU takes 1 hour 30 minutes versus only four seconds on the GPU. Go further to 7 characters (fh0GH5h), and the CPU would grind along for 4 days, versus a frankly worrying 17 minutes 30 seconds for the GPU."
And any system worth its salt (crypto-hashing joke) won't allow that many attempts against any external or internal authenticator and will NEVER expose its password hashes.
Seriously, if someone has your password hash, it's game over anyway and it doesn't matter if it takes 2 weeks or 2 months to guess the passwords. And if they don't, then you shouldn't be letting them try several BILLION attempts at guessing a password anyway.
Go further to 7 characters (fh0GH5h), and the CPU would grind along for 4 days, versus a frankly worrying 17 minutes 30 seconds for the GPU."
OK, so go to 15 characters. Using a password generator I can go as far as I like. Using some sort of password bank program, I can store passwords / phrases of any complexity and use copy and paste, thus having only one strong password to remember.
So, what am I missing? (And lets keep it on topic, folks).
Faster! Faster! Faster would be better!
It is well known that if someone gets your hashed password, it is as good as cracked. 17 minutes vs 4 minutes is irrelevant.
On a live system, it is quite another story. You can't just remotely try 3.3 Billion passwords per second.. You'll be locked out after 10 attempts or so.
This is about offline hash cracking, not bruteforcing passwords over a network connection.
Emotions! In your brain!
3m are going to introduce a larger post-it-note
The title of the article is extremely misleading.
I don't really care that someone can break short passwords generated via MD4. MD4 is very broken. NTLM is essentially 1992-era technology that was later picked up by Microsoft, who now deprecates its use.
When a GPU can break 15-character AES256 keys, then I'll start to worry about the security of my 24-character key.
Am I part of the core demographic for Swedish Fish?
Even for Slashdot, this is a little pathetic: the link is to a ZDNet article, which regurgitates a PCPro article, which in turn regurgitates a blog post by the guy who actually ran the tests, Vijay Devakumar. And here's Ivan Golubev, who wrote the cracking tool.
Still, ZDNet's advertisers thank you for the hits!
Your shameless plug is correct, but for one problem:
When you use a fingerprint sensor, the traditional attack methods (brute forcing, social engineering, etc) still work. But you also add a new attack method, by generating a fake fingerprint from that coffee cup you threw into the trash that morning.
Needless to say, increasing the possible attack vectors decreases security, rather than increasing it.
"City hall" in German is "Rathaus" Kinda explains a few things......
It doesn't work like you think it does.
Basically, most modern password protection techniques work like this: they take a password, say "my nice password" and transform it into a hash, say :"uq10ajg901a0##". Now only the hash is stored on the system. There is no way to go from the hash to the password. Classical hash functions are MD4, MD5 and SHA1. NTLM users MD4. Linux mostly uses MD5. There are added niceties likes salt, etc. You can look these up if you want.
When users enter their password, they are hashed again, and the *hash* are compared, not the passwords. If you enter the right password, no matter whether this is a nice word or sentence or jumbled letters, the system lets you in.
Crackers simply assume that the *hash* is available. It is in fact very easy to get it if you have access to the console, both for Linux or Windows. They then generate any and all combination of letters, signs, symbols and so on as input as potential password, they compute their hash, and they compare it to the hashes they know. If there is a match, bingo, they have found the password.
So the upshot is it doesn't really matter what the input password look like as long as the crackers can generate it and compute their hash. If the crackers know that you have used only letters, however, they can cut down dramatically on the numbers passwords they have to generate and save time.
So in some sense you are right but not for the reason you mention.
Hope this helps.
"The Sun would burn out first."
Especially if it's an old Ultra 5.
http://www.rootstrikers.org/
It is well known that if someone gets your hashed password, it is as good as cracked. 17 minutes vs 4 minutes is irrelevant.
Bullshit. It is well known by people who don't know what they're talking about, which includes TFA.
Do you seriously think that in the age of bitcoin we can't make a hash function that is arbitrarily difficult?
Use an adaptive cryptographic hash function: bcrypt, PBKDF2 or scrypt. The key feature is a tunable stretch factor that basically sets the number of rounds of hashing. Set that factor (by means of a simple timing loop) to require 1 second of CPU time (or GPU time or whatever) to hash.
Now the simplest 8 character A-Z password will take an expected 3,311 years to break. You'll obviously want a safety margin, and will expect them to have more computing power a few years down the road. But you can tune the stretch factor to ensure that a reasonably strong password is perfectly good against offline attacks.
The quicker CAPTCHA dies the better.
Not only does it discriminate against machines (like it should) it discriminates against humans, too.
I long for the day when the Americans with Disabilities Act gets amended for the interbutt. You are an institution or you do commerce on the Web? You can no longer discriminate against the sight impaired ever again.
Most of the big name CAPTCHAs I've seen have an audio alternative, so what's the issue?
Same shit with all the scare on rainbow tables. I remember the hype of "It can crack any password in seconds!" Then I found out it meant any LM password, which has some real limitations on it (14 characters total max, as two 7 character hashes, no upper and lower case). Ahh, not so impressive then.
Same shit with NTLM. Worlds better than LM, but not current. Wake me when it is a threat vs NTLMv2, which is what Vista and 7 use exclusively unless you manually change security policy (and XP and 2000 support it).
Then there's the fact that they are talking about short passwords. Security comes in length and it goes up drastically with each character. They are crowing on about how easy 7 character passwords are. Ok, fine, try 14 then. It isn't like if 7 takes 18 minutes 14 takes 38 minutes. It is more like if 7 takes 18 minutes 14 takes years.
Also to make a long, secure, password doesn't have to be that hard. Just take a phrase and modify it a bit. Say you decide the phrase "There can only be one," should be your password. Do something like "Th3r3 can only be #1!" Fairly easy to remember, yet you have to exhaust a massive space for a brute force attack.
Finally, all this is an attack against the hashes. While we want hashes to be strong, let's face it they are a last line of defense. This is a situation where someone has already gotten in, gotten high privileges, and stolen that list. This has no relevance to dealing with breaking in to a random system remotely.
Pretty much this is just fear mongering. Yes, you need to use longer passwords these days. So do so. However a short password really isn't as bad as they make it seem. The risk they are talking about here is only if someone happens to get the hash file from a system with NTLM passwords stored that you use a short password on. Given that the only system that qualifies for that for most people is their home desktop, if they get it the hacker has owned your system already (you have to have admin to get the SAM file) so it doesn't matter.
Let's look at some alternative alternative math: that 3.3 billion passwords/sec were at http://www.golubev.com/files/ighashgpu/readme.htm. Note that this is the speed for cracking MD5 passwords, which were deemed "almost ready to crack" a few years ago. Modern Linux systems all support sha256 and sha512 hashing; given that this tool is 1/3 slower for sha1 (aka "sha160"), one can guess that current sha2 (sha256/sha512) algorithms will be slower. It's also worth nothing that the algorithms supported by the tool mentioned in the article are *all* not supposed to be used as of 2009: http://csrc.nist.gov/groups/ST/hash/policy.html; the tool doesn't currently even support the sha2 algorithms. The common algorithms which are currently supported (ie, md5) have been breakable in fractions of a second through rainbow tables for years anyway - which was NIST's point, IIRC.
I suppose I'll also note that the Ubuntu 11.04 system I'm typing this upon right now is configured out of the box to use sha512 hashing in /etc/shadow (check /etc/login.defs on most Linux systems, look for password strings which start with $6$). Assuming the use of PAM for anything important and passwords stored either in root-only shadow file or in an LDAP directory which does compare-only access or server-side hashing, and a secure transport such as current TLS, then this is a non-issue on a Unix system which hasn't already been compromised. It'd be easier and probably more effective, as usual, to socially engineer a password (or otherwise gain access through the human interface weak point) than to get password hashes and break them.
It's not that simple. Cryptography is an asymmetric game: you always have to assume the attacker has orders of magnitude more computing resources than the target. Cryptography works because we can (usually) find problems that get exponentially harder and harder to crack. For instance, let's say you just want to encrypt something. A block cipher with a 64-bit key is just on the edge of being brute-forcible today. But, as a general rule, you could use a block cipher with a 128-bit key and it should only be half as fast as the 64-bit cipher (note I said this is a general rule, there are number of factors that influence speed). A 128-bit block cipher is 2^64 times more difficult to crack than a 64-bit block cipher. So, the target can make something 2^64 times more difficult to crack by just doing twice the work.
Your proposed solution just grows linearly, not exponentially. If you iterate SHA-1 10,000 times instead of just 5,000 you're also doing twice the work, but this time you've only made your password twice as difficult to crack. If you can suddenly start doing twice the work you did before, you have to assume the attackers can as well.
Yes, iterating hash functions buys us more time, but this is a game that targets can't win. Plus, you're ignoring all of the problems associated with moving to higher iteration counts. Probably first and foremost is interoperability. There's a massive application base out there that just uses MD5 or SHA1 with little to no iteration. It's not easy for software like Windows to change. I think it wasn't until Vista that Microsoft stopped storing a LAN Manager hash of users' passwords, which made then trivial to break. That's been known to be bad for a long, long time. Plus, in most web-based applications its not the client that does the hash operation, its the server. While your new Core i5 processor could probably easily handle bumping up the iteration count by an order of magnitude or so, Google's Gmail servers probably can't.
Longer, more complicated passwords would be more effective than increasing iteration counts, but people are bad at generating and remembering long passwords. So, the only long term solution seems to be moving to stronger forms of authentication, like smart cards or using devices like smart phones as one-time password devices.
Strictly speaking, NIST still allows the use of SHA-1 for password hashing. NIST says you shouldn't use SHA-1 for anything that requires collision resistance. Password hashing doesn't require collision resistance, it only requires preimage resistance. In fact, there's relatively little benefit to using SHA-256 or SHA-512 for password hashing, since they're not that much slower than SHA-1 and its not much harder to generate and store a SHA-2 rainbow table than a SHA-1 rainbow table.
The page you referenced is from 2006, and NIST has backed off on their warnings about SHA-1 a little bit. The collision attack on SHA-1 probably isn't as bad as it looked in 2006. The attack hasn't improved- some of the alleged improved attacks turned out to have errors in them. No one has ever found a collision using SHA-1. Some people aren't even sure the claimed collision attack even works, though the general agreement is that even if the specific attack outlined in Wang's paper doesn't work, there probably is a similar one that does work.
In the mid 2000's the cryptographic community just saw both of the widely used hash functions attacked- SHA-1 and MD5. There were a lot of people concerned that the attacks would soon be catastrophic. That certainly didn't come true with SHA-1, and its only partially true with MD5 (which still has decent preimage resistance).
Still, telling people to move to SHA-2 is good general-purpose advice. It can be tricky to determine when you need collision resistance and when preimage resistance will do.