**Note: The content in this article is only for educational purposes and understanding of cybersecurity concepts. It should enable people and organizations to have a better grip on threats and know how to protect themselves against them. Please use this information responsibly.**
Crunch: A wordlist Generator
- Objectives
- Basic Structure
- Pattern Specific Wordlist
- Permutation
- Break wordlist into chunks
- Wordlist Compression
- Handle frequency of characters
- Inversion of output
Crunch
Crunch is a wordlist that generates a utility used to create a wordlist using numbers, letters, and symbols. Mostly Hackers, Penetration testers use this tool to create passwords. The crunch comes pre-installed In Kali Linux.
Basic Structure
Crunch <min><max> -o <filename>
Fig1: Basic structure
- min: It is the minimum password length.
- max: It is the maximum password length.
- charset: Character se to be used.
- -o : Output in a textfile, along with name of the text file.
Charset: In charset we have three options
- Default: Uses small alphabet (Fig1).
- User-defined: User defined which charset wants to use.(abc.. , ABC… ,123…, @#$%^*)
- Crunch charset: It has its own charset. If we want to use charset of crunch we have to change directory (/usr/share/crunch) and we fined charset.lst in it.
Crunch charset: Crunch <min><max> -f /usr/share/charset.list mixalpha | more
Pattern specific wordlist
-t: indicates pattern
Scenario 1: Normal condition
- @ – Lowercase
- , – Uppercase
- %- Number
- ^- Symbol
Syntax: Crunch <min><max> path -t //%%(using two upper case letter and 2 Number) below we used only upper case.
Scenario 2: If password is a phone number than
- @ – Lowercase
- , – Uppercase
- %- Number
- ^- Symbol
Syntax: Crunch 10 10 path -t %%%%%%%%%%%(we have to use ten % sign)
Scenario 3: if password length is 7or8 char including name,@ and number
- @ – Lowercase
- , – Uppercase
- %- Number
- ^- Symbol
Syntax: Crunch 7 8 charset -t name@%%% -l aaaa@aaa |more
-l is used so that @ used as it is.
Permutation
In permutation it used only john, pet and jan to create password
Now saving john, pet, jan and 123 in .txt file.
Break Wordlist into chunks
It breaks wordlist into two:
- Lines : After limit it creates new file(e.g. if we use 10 as limit than after 10 lines new file creates and this continues till all password over).
- Storage: After limit it creates new file (e.g. if we use 2MB as limit of a file than after 2MB it creates new file).
Wordlist Compression
For compression we have .gzip .bzip2 .lzma .7z etc.
Handle frequency of characters
Syntax: crunch 6 6 timtat -d 2@ |more
Inversion of output
Syntax: crunch 8 8 -t pass@%%% -l aaaa@aaa -I |more
