Some remarks and maybe idea for improvement
#1
After usual default, wordlist, rule, hybrid approach i turn to mask approach. Since ?l(same with ?u) goes through all characters randomly, without any rule(almost), i thought this is not optimum approach. The reason is that when we fish for a password, which can resemble english language(i have three languages to worry about), it follows at least *some* linguistic rule. For example, by cycling through all characters(a-z) one by one in rockyou(for example) with command

fgrep -o a rockyou.txt | wc -l

it finds different occurence frequencies of those characters. By sorting those characters by frequencies, i found that it follows the rule of - "aeionrlstmcdyhubkgpjvfwzxq". That is, from most frequent character to least frequent character. With only this finding i could throw away 3(zxq) last characters, which would exclude about 1,9% of the characters and 2.088 x 10^11 (26^8) combinations turn into 7.83 x 10^10 (23^8). It means cracking time is reduced by 62%. Then i can turn to some other mask(with same approach) and later, when most frequent characters are used and hashes are not cracked, i turn to the least frequent characters (probably not, it may take too much time).

An important thing which i quickly realized is that first character and second character follow different rules. So after cycling through all characters based on the first position with the command

cat rockyou.txt | cut -c1-1 | fgrep -o a | wc -l

i found a different picture - "msacbljtdpkrnghiefwvoyzuxq", from most frequent to least frequent. The second character frequency line is - "aoeiurlhnmsytcdbpkjwqvf".

To cut long story short, i started doing cheesy tactics, where i started doing masks with longer lengths, but with truncated character set(starting even from first 14), from most frequent characters to least. -1 as the first character, -2 as second character and -3 all other characters. Then after exhausting(or cracking some hash) i started adding less frequent characters(to max 18-23). This is all manual and sometimes exhausting(adding characters one by one on a 8 length mask, where -3 occupies 6 slots, i have to go through all combinations manually), but the time reduced is big.

So here is the question. Is there a possibility to do this more automatically, where hashcat adds characters one by one in the mask without hitting duplicates? Well, to try to answer myself, i turned to brain solution, which is a little bit more automatic, but still doesn't solve everything and i had to set --brain-client-features 3, cause with the default approach, the custom character set doesn't work well("-1 m" only on first char, then "-1 s", then "-1 ms" should reject 100%, but doesn't). This also slows down the speed, depending on how many hashes i have.

The approach from the most frequent character set to least is comparable to mask attack, where we choose most frequent mask(ullllldd or lllllldd) to least.

So, what do you think?
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Some remarks and maybe idea for improvement - by hashserious - 05-09-2019, 11:43 AM