Combinator attack missing correct candidate on large wordlist
#1
Hey y'all.

I am teaching myself the ropes of Hashcat by specifically working on creating and refining wordlists to test against Comcast Xfinity modems and WPA2.  The default format of these passphrases is a five letter word, four digit number, and a six letter word.  An example would be build2373guitar.  I've captured handshakes from two separate modems for which I know the passphrase for testing.

For the left side wordlist, I parsed the Google 20k list for 5 letter words and used combinator to create the list with all 5 letter words, each with a number 0000-9999.  Call this left.txt.  For the right side, I parsed the same Google 20k list for 6 letter words.  Call this right.txt  For the example above, I can use the command "cat left.txt | grep build2373" and see that the matching left side is in the file.  Same for the right side.

From here, I can test the combinator within hashcat to ensure my command will encounter the correct candidate:

hashcat -m 22000 -a 1 -w 3 --stdout left.txt right.txt | grep build2373guitar

The list is large, so this takes a while, but it always finds the correct candidate.

Where the rubber meets the road is the problem.  An example of the command I've used is as follows:

hashcat -m 22000 -a 1 -w 3 comcast.hccapx left.txt right.txt

I've put two separate hccapx's through knowing the correct candidate will be created, and it has exhausted both times.  I've also split the left side in half to create smaller batches of candidates and still no luck.

In an effort to ensure my captures are good and hashcat is working I have verified successful cracks with the following:

Create text file with the correct candidate, call it winner.txt.  Run the following command with success:

hashcat -m 22000 -a 0 -w 3 comcast.hccapx winner.txt

Create left side with only the correct 5 letter word and digits 0000-99999, call it build.txt.  Combine that with my usual right side with success:

hashcat -m 22000 -a 1 -w 3 comcast.hccapx build.txt right.txt

So this seems to be an issue relating to processing a large amount of candidates.  My GPUs are an RX580 and a Vega 56.  Is it possible that one or both is putting out bad hashes under load?  They're not overheating, and output otherwise seems good.  Is there a way to test this?  Is there something else I am missing here?

Thanks for the input in advance!
Mike
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Messages In This Thread
Combinator attack missing correct candidate on large wordlist - by antimatterizer - 03-26-2020, 04:24 PM