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Letters-Only LM Hash Database
Peter Clark writes "Disk storage has increased tremendously in the past 5 years and the blatant insecurities in the antiquated LM hashing technique have not gone away; though functionality has been added to disable LM hashes, this is not set by default. With some help from Elcomsoft, simple flat files have been created that hold every combination of LM hash for letters only passwords. Jesko has coded a server application which allows you to access this database. Simply telnet to: beginningtoseethelight.no-ip.org on port 2501 and paste in a LM hash. So how does this differ from Rainbow tables? Well this will return a password 100% of the time, using minimal processor power, in approximately less than 0.2 seconds."
There's gotta be a better way to model what a user's password can be than just all combinations of only letters, or a list of common passwords plus substitutions. I think these are the only ones I've seen. But this doesn't really reflect that "fiqojeio" is a much less likely password than say "foo7bar+".
I think this sort of attack could get much stronger than people expect if there was some sort of Markov-process-ish way of generating plausible passwords. I mean, if Google can guess when you spelled something wrong, these programs should be able to figure out which strings are more likely to be passwords. Or maybe I'm overgeneralizing by how I pick my own passwords....
"TV is great! Every New Year's I make a resolution to watch more TV." - Ann Coulter
Geez lets hope they are not logging password lookups vrs IP addresses Mwhahahahahahahah
In fact, this would be a really cool project to break up into pieces. Bob takes everything starting with A|a, Steve takes B|b, etc... Then just build a front end (accessable via telnet) that passes each query off to each back end and returns the results. You could even hack together a simple Java client that would bang against an LM password file. Instant cracking tool - cool!
KangarooBox - We make IT simple!
Even worse, take the hashed PW, run it through the site, and if it DOESN'T return the password, you've already eliminated a large chunk of possibilities from your (next step) brute force attack.
Now, admittedly, it would still take ungodly long time to crack all the next possibilities, but it does save SOME time.
This also makes one wonder if the next generation of password cracking is to distribute the terrabytes of pre-digested passwords across multiple systems so that you have the "numbers only" database, the "upper and lower case letters" database, etc; let multiple crackers/hackers share their efforts in a similar way.
Or... err... maybe I shouldn't have suggested that in a public forum. 8D
Diplomacy is the art of saying, "Nice doggie!" until you can find a rock.
I tend to use uppercase, lowercase, numbers, and punctuation. An example might look like: s1mhm$tM-BIdc! (just off the top of my head, and memorable to me)
Most people do have horrific password security though...
-- Pete.
Monochrome - Probably the UK's largest internet BBS
It is well known that the LM (LanManager password) hashing technique used by older Windows OSes (thru WinMe) is insecure. Now someone has really pointed this out by simply saving all possible password hashed in a database made possible with today's cheap, large disk drives...
But that wouldn't be nearly as much fun - by being vague you get many more posts correcting grammar, explaining what should have been there in the first place, etc.
In short, better writing might promote more useful comment posts, and we wouldn't want that on Slashdot.
This issue is a bit more complicated than you think.
He is not joking. And he didn't tell the whole story either; there are several either tremendous stupidities in the LM hash which makes long passwords worthless, and relatively short ones easier to break than their length would otherwise indicate (separate grouping of characters, triple-DES'ed *independently*).
:)
The fun part is that any default install of Windows (at least up to and including XP) will send out the current users LM hash if he tries to connect to a SMB share.
So, if someone placed a link on their homepage to a patched Samba which logged LM hashes, they could gather LM hashes from most of their windows using visitors.
This would *include* those behind many firewalls, because many default firewall setups will allow *outgoing* connections - and in this particular case, it is indeed the windows client that is initiating the connection to the remote web server in order to send away the current users LM hash (along with username, domain, local machine name and other goodies).
Yes, I told CERT about this some three years ago. They wouldn't touch it with a five foot pole. I then told Microsoft about it. Their response was something like "fixing that problem would require us to re-design our windows networking layer - therefore it is not a security problem".
Well, there you have it.
But hey, if you're on Windows you're fucked anyway, and none of this should really come as a shock to you
A buddy of mine works in Network Security, so for something to do and cause it would help him with his job we made our own rainbow tables. The time it took and disk space is roughly as follows.
5 average pc's ( all about 2000Mhz or so ) took about 30 days, and generated about 18Gb or tables.
Now these tables give us about 95%+ hit rate on any LM Hash we , erm "acquire"
The tables contain all hashes upto 14 Chars length using all letters all numbers and some symbols.
Just about the only hashes these tables wont hit are the machine generated ones.
I guess the point is turn *OFF* LM hashes at all cost, and if you absolutely "must" use them, make sure you kept them secure!
oh and a side note, if you are interested in cracking / brute forcing LM hashes, make sure to run them thru a copy of L0pht Crack or some such to get all the Blank, Pass==Name, Pass==Name-reversed hashes out of the way first.