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Problems with prefix rule. - Printable Version

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Problems with prefix rule. - Hash-IT - 05-17-2012

Sorry to be a little vague about his for now but I thought I would just ask this quickly before making any further investigation myself.

I seem to be having trouble with the prefix (prepend) rule when using oclHashcat-plus. I have been testing on MD5’s for simplicity as I normally work on WPA only. I was trying to modify some of my rule lists and noticed this problem.

My problem seems to be when using oclHashcat-plus .7 on an old XP pro computer and prefixing more than 2 characters using rules. oclHashcat-plus fails to find the password.

For example, my password list contains the word “test” and my rule file contains ^1^2^3.

I MD5’d 123test and tried to find the password using the above password list and rule file. Hashcat failed to find it, however I can find other test words with less than 3 prefixed characters such as “1test”.

Can anyone please take the time to see if this happens to them or let me know if I am doing something wrong ?

I do know how to basically use hashcat and I have no trouble with suffixed rules, just prefixed ones.

Thank you.

RE: Problems with prefix rule. - undeath - 05-17-2012

you have to reverse the order for prepending.

^1^2^3 + "test" -> ^2^3 + "1test" -> ^3 + "21test" -> "321test"

RE: Problems with prefix rule. - Hash-IT - 05-17-2012

Hi undeath and thank you for taking the time to reply, you have saved me a lot of frustration.

I had no idea that the prefix rule worked in reverse !! I have just tested now using your method and it worked, thank you very much.

“test” in my password list, ^3^2^1 in my rule file using this MD5 abe45d28281cfa2a4201c9b90a143095 and hashcat finds 123test.

Can I ask how you knew it worked backwards as I did look in the rules instructions but couldn’t find this.

Thank you very much for you help.

RE: Problems with prefix rule. - M@LIK - 05-17-2012

Simply the rules apply from left to right:
^1^2^3
Code:
^1                ^2                ^3
^1 === 1test  >>> ^2 === 21test >>> ^3 === 321test
BUT:
^3^2^1
Code:
^3               ^2                ^1
^3 === 3test >>> ^2 === 23test >>> ^1 === 123test

I hope undeath doesn't mind me "butt"ing in. xD

RE: Problems with prefix rule. - Hash-IT - 05-17-2012

Thanks for your input M@LIK.

I was just starting to work it out but the diagram you made (quoted below) really helped me visualize it, so much clearer now and in fact I am rather embarrassed I didn't see it sooner.

(05-17-2012, 01:06 AM)M@LIK Wrote: ^3^2^1
Code:
^3               ^2                ^1
^3 === 3test >>> ^2 === 23test >>> ^1 === 123test

Thank you both for your help.