John the ripper rules examples11/7/2022 ![]() You will need to provide a set of cleartext, a dictionary, and it will work on its own in order to produce a good set of rules.Ī naïve idea for finding the best set of rules would be to: ![]() It aims at being a lot easier to use, and a lot more efficient. This project is a spiritual successor to rulesfinder, and shares its name. While not having the best methodology (training and validation sets are identical), the winner ( Arex1337) produced a set of 64 rules that is quite good in practice In 2012, the best64 challenge ( forum thread) goal was to find the set of 64 rules that would be the most efficient for cracking a given set of hashes (the leak) with a given dictionary (so called top10k).In 2011, I started working on rulesfinder, the predecessor to this tool.MotivationĬreating a set of mutation rules that is efficient has mostly always been about hunches and experience. If you want to soak in all the gory details, please take a look at the John the Ripper or hashcat variants. While it might have been better, in hindsight, to optimize for readability, it is not so bad once you are used to it. The rule description language is very terse (yes, it looks like a golfing language). The corresponding rule could be cAz"123!". One could observe that in order to go from sunlight to Sunlight123!, the user has capitalized a known word, and suffixed it with 123!. That system was reused and extended in John the Ripper and Hashcat, where it is known as password mangling rules, or, simply, rules. For example, instead of sunlight, someone could use Sunlight123!.įrom this observation, Alex Muffett implemented in Crack (the first standalone password cracker) a system of rules that simulates these little twists. However, people usually do not directly use common words, but twist them a bit. For this reason, they are much more likely to use a password like sunlight than That is why the most efficient strategy for cracking password usually is the "dictionary attack", where the candidates are picked from a dictionary of common passwords. In order to crack as many hashes as possible, we can try to reduce that cost (optimize the "check" step, speeding up the password cracking process), or to be clever about candidate selection (increase the probability that a candidate matches).Ī key observation for password crackers is that people who do not use password managers choose passwords that they can remember. Of course, checking if a candidate matches a hash has a cost. ![]()
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