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 Post subject: Brute Force Dictionary
PostPosted: 15 Nov 2007, 07:42 
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Shoulder Surfer

Joined: 15 Nov 2007, 07:22
Posts: 9
I have been trying to crack a cache dumped password, and rainbow tables have been unsuccessul on every attempt. I even created a domain account: USER: 'user' PASS: 'dog' and rainbow tables could not crack it. I put the cache dump into Cain & Abel and a dictionary found the password in under 10 seconds.

This brings me to my project idea. I have been working on this for about a week now and am running out of processor power as the text files are getting MASSIVE. I currently have four computers working on this, but it is not enough. I created one text file 70 lines long, with 70 characters: a-z (lowercase, since Cain does case perms), 1-0, all 32 symbols, space, and null. I named this file 1DIG.txt.

The next file, 2DIG.txt, contains each of the 70 characters, each one having all 70 after.

Example:
File 1:
a
b
c
d

File 2"
aa
ab
ac
.....
ba
bb
bc
.....

I am currently about halfway through the fifth file: aaaaa, aaaab, and so on to [null][null][null][null][null].

Would anybody be willing to help me out with a distribution project, similar to DitrRTgen, for brute force text files? I think this would work quite well seeing as how C&A can run through the four digit file (24,010,000 "words") in under a minute.

This project may end up being QUITE large, but look at rainbow tables. What is a full alpha_num_sym32_space set of tables... 112GB?

Like I said, rainbow tables do NOT work on cache dumps, and a typical brute force can take over a year, so I figured this was the next step.

What are your thoughts?


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 Post subject:
Posted: 15 Nov 2007, 08:16 


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PostPosted: 15 Nov 2007, 08:16 
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Guesser

Joined: 19 Oct 2007, 07:27
Posts: 40
Unfortunately, this project is infeasible. In addition, if you don't precompute the hashes for every entry in your dictionary and store them somehow, this approach will be slower than brute force. Cain generates such lists of "words" on the fly when it is brute forcing - reading them from a HDD will be slower than just incrementing the characters and string length.

Imagine creating a dictionary which covers the same character set as the lm_all set. This covers 72 characters, so lets increase the number of characters in the dictionary to 72 to make comparison possible. The lm_all 1-7 set of tables is 66GB. Your dictionary file would be 72^1 + 72^2 + 72^3 + 72^4 + 72^5 + 72^6 + 72^7 characters, which is 10171889243784 bytes. This is 9,473GB. In addition, it doesn't contain the actual hashed strings, which would add an additional 16 bytes (for an LM hash) for each line in the dictionary.

Sorry to burst your bubble :(

Also, rainbowtables do work on cache dumps (as long as they aren't salted). Can you specify more what process you followed to obtain the hashes?


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PostPosted: 15 Nov 2007, 08:40 
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Shoulder Surfer

Joined: 15 Nov 2007, 07:22
Posts: 9
I used cachedump to retrieve the passwords, and yes they must be salted.

The text files would not have to have hash strings because this is basically just a dictionary type attack, but with brute-force strength.

You are right though, this is not feasible. I looked at the four files I have thus far, and the file sizes are incrementing by a factor of about 94.2 times (end-of-line takes up file space too). To take this out to 9 places would end up being over 1 million TeraBytes. =(

You have any ideas on cracking this password? I have the SAM and SYSTEM files for the local accounts, but I want the domain password from my cachedump.


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PostPosted: 15 Nov 2007, 08:41 
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Shoulder Surfer

Joined: 15 Nov 2007, 07:22
Posts: 9
Sorry, more specifically...

I logged into the local admin account and ran cachedump.exe

Am I missing a step here?

Here is the dump with username and domain changed for security reasons:
user:7D15366E7344B5DAC940079F5795BD9F:domain:domain.local


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PostPosted: 15 Nov 2007, 08:49 
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Guesser

Joined: 19 Oct 2007, 07:27
Posts: 40
MotoCrazy wrote:
I logged into the local admin account and ran cachedump.exe

Am I missing a step here?


That sounds right to me.

I'm pretty certain that cached passwords from domain logins are salted. This makes rainbowtables useless, unless they are created for a common salt, which really shouldn't exist (reusing salts defeats part of the purpose of salting, but hey, M$ is happy to do it).

Your only options for cracking it are dictionary and brute force. Get your hands on the best dictionary you can, run it through Cain with some of the word mangling options on, and hope for the best.


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PostPosted: 15 Nov 2007, 14:58 
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Site Admin
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Joined: 18 Oct 2007, 12:42
Posts: 186
MotoCrazy wrote:
The text files would not have to have hash strings because this is basically just a dictionary type attack, but with brute-force strength.

Which, as stick said before, would be slower than just generating the strings on the fly.


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PostPosted: 16 Nov 2007, 04:31 
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Shoulder Surfer

Joined: 15 Nov 2007, 07:22
Posts: 9
Is there any way to figure out the salt?

There are three accounts in the dump, two of which I already know the passwords for. Given these two salted MD5 hashes and their passwords, is it possible to determine the salted encryption?

I have a copy of the alpha_num_sym32_space tables, so also is it possible, once the salted encryption is figured out, to add the salt one-time to these tables? I have 2TB storage, so that is no issue. What time constraints would this create, if possible?

I have a friendly $5 bet with my network admin that I can crack his password. Who cares about the $5, but I want to figure this out for personal gratification.


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PostPosted: 16 Nov 2007, 05:23 
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Guesser

Joined: 19 Oct 2007, 07:27
Posts: 40
MotoCrazy wrote:
Is there any way to figure out the salt?


It's the username.

MotoCrazy wrote:
I have a copy of the alpha_num_sym32_space tables, so also is it possible, once the salted encryption is figured out, to add the salt one-time to these tables? I have 2TB storage, so that is no issue. What time constraints would this create, if possible?


I'm not sure I understand your question, but you can't modify rainbowtables once they have been created.

There's no point making rainbowtables to crack this hash, as you are only going to use them once. Rainbowtables are useful because they as as effective as a bruteforce attack and as efficient as a dictionary attack. They take longer to create than it takes to bruteforce the same keyspace, so they are only useful if you can reuse them many times.

The hash you have is not MD5, it is MSCASH. MSCASH = MD4( MD4(password ) || lowercase(username) ). As you can see, the password is hashed, the username is appended, then the whole lot is hashed again. At least, I'm pretty sure that's right.

The fastest method will be a dictionary attack. If that fails, you have to brute-force this hash.


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PostPosted: 17 Nov 2007, 08:10 
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Shoulder Surfer

Joined: 15 Nov 2007, 07:22
Posts: 9
stickmangumby wrote:
...but you can't modify rainbowtables once they have been created.


That answers the question. Thank you.

You say that a cachedump is MD4; is there any way to figure out how to remove (or reverse) the salt given known username and password combos from the same machine? For instance, I know the passwords to two accounts and ran them through an MD4 hash generator.

33BC5AAEDD45A367190336C998D588ED salted (from cachedump)
equals
95EEA894D67AA756928D50D1234DC9E9 unsalted (using an MD4 hash generator)

and

C5846A3D2F887ED6435CDE69E0BC1645 salted
equals
DBBB1B46E505FA6F789DDDF13D5BBF19 unsalted

Can this be done? It seems logically possible, but don't know if it has been (or can be) done.

By the way, I appreciate your responses! Learning new stuff every day.


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PostPosted: 17 Nov 2007, 08:57 
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Guesser

Joined: 19 Oct 2007, 07:27
Posts: 40
MotoCrazy wrote:
... is there any way to figure out how to remove (or reverse) the salt given known username and password combos from the same machine?


It's not possible to reverse a hash to find its plaintext, even if its plaintext is another hash. A hash function is a one-way function. The final MD4 hash contains less information than the intermediate MD4 hash concatenated with the username - there is no way to get it back. If you MD5 hash a file, regardless of its size (1kB - 100GB - anything), the resulting hash is always the same length. The information that you 'discard' cannot be regenerated from the hash.

MotoCrazy wrote:
By the way, I appreciate your responses! Learning new stuff every day.


You're welcome :)


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PostPosted: 04 Mar 2008, 02:12 
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Shoulder Surfer

Joined: 04 Mar 2008, 02:11
Posts: 2
Are all mscash passwords in windows salted by default?


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PostPosted: 04 Mar 2008, 07:49 
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Site Admin

Joined: 11 Oct 2007, 21:17
Posts: 1618
Location: Copenhagen, Denmark
AlephOne wrote:
Are all mscash passwords in windows salted by default?


Yes. It's salted with the username


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PostPosted: 30 Sep 2008, 07:43 
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Shoulder Surfer

Joined: 30 Sep 2008, 06:54
Posts: 1
Well, this is a tight program

it creates a dictionary every avliable password there is:
(in word-with-number(e.x. ab1 ac2 or ab ac, etc...) so anyword will be there to)

Load the file it creates into the password cracker, and start cracking!!!!
It works , and has a nice plain simple interface0


i use this program you can ask me any question ?

_________________
Http Brute Force


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PostPosted: 30 Sep 2008, 09:14 
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Shoulder Surfer

Joined: 20 May 2008, 13:30
Posts: 18
Though it is an old thread:

Why should one compute all combinations and then write them to a file, load that file into memory and read it out to get the combinations again and compute their hashes instead of quickly compute the hashes on the fly and save half of the time or more?


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PostPosted: 03 Oct 2008, 17:04 
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Guesser

Joined: 30 Aug 2008, 20:01
Posts: 34
One of private versions of BarsWF have working support for MSCACHE hashes. Speed is around 52% of MD5 one (like 200 millions per second on 9600GT).
This will be available at sometime for everyone.


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