How to Generate a Custom Wordlist with Crunch?

Crunch Tool
Commands and Options

Option	Description
-o <filename>	Specify the output file to save the generated wordlist.
-t <pattern>	Generate words based on a specific pattern (e.g., -t @@@@ for 4-character words).
-p <pattern>	Generate permutations of the specified pattern.
-s <string>	Specify a string to prepend to each generated word.
-e <string>	Specify a string to append to each generated word.
-l <length>	Specify the length of the words to generate.
-c	Only generate words that are of a certain length.
-f <filename>	Use a file as input for generating words (e.g., using a list of words).
-i <string>	Insert a string at specified positions in the generated words.
-b <num>	Generate only a certain number of words (limit output).
-n	Include numbers in the output (digits).
-h	Display help information about the tool and its options.

Example

·       
Example
1: Basic Wordlist
(Generate lowercase letters of length 4-6)

• • crunch 4 6 abcdefghijklmnopqrstuvwxyz -o
wordlist.txt

·       
The crunch
command can be used to generate a simple wordlist composed of lowercase
letters. For instance, produces passwords that are 4 to 6 characters in length,
using only lowercase letters. The resulting combinations are saved to the file wordlist.txt, making it a straightforward option for creating basic
password lists. 

·       
Example
2: Alphanumeric Wordlist
(Generate letters and numbers of length 3-4)

• • crunch 3 4
abcdefghijklmnopqrstuvwxyz0123456789 -o wordlist.txt 

·       
To generate a
wordlist consisting of alphanumeric combinations, you can use the crunch
command with a specified length range.  creates passwords that are either 3 or 4
characters long, using lowercase letters and numbers. The generated
combinations are saved to the file wordlist.txt,
making it a useful resource for various password-cracking tasks.

·       
Example
3: Generate a specific pattern of passwords:

• • crunch 10 10 0123456789@ -t tester@%%%
    -o generated_passwords.txt 

·       
Generates
10-character passwords starting with the prefix “tester,” followed by
a single lowercase letter or symbol represented by @, and
ending with three characters from the specified character set (digits and @).
The results are saved in the file generated_passwords.txt, showcasing the tool’s flexibility in producing targeted
wordlists for password cracking.

Example
4: Generate Passwords with Special Characters

• • crunch 10 10 @ -t tester@%%% -o
generated_passwords.txt 

·       
The crunch command is an essential tool for creating custom
wordlists, particularly useful in password cracking scenarios. This example
demonstrates how to generate passwords with a specific pattern, including
special characters.

·       
Example
5: Generating Wordlist Combinations with Crunch

• • crunch 3 3 -t aaa -p admin user tester
-o wordlist.txt

·       
In this
section, we demonstrate how to generate a wordlist of permutations from a set
of specific words using the crunch
command. This command is useful for creating custom wordlists for penetration
testing and security assessments.

Dynamic Wordlist Generation with Crunch for Password Cracking Tools (Without Saving)

 

Introduction

In this section, briefly explain the significance of password cracking and how dynamically generating wordlists with crunch enhances the effectiveness of various cracking tools without the need for saving intermediate files.

 Aircrack-ng

Command: crunch 8 8
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 | aircrack-ng -b
[bssid] -w - [file.cap]

Explanation:

• This command generates passwords of length 8 and pipes them directly into aircrack-ng to crack WPA/WPA2 handshakes.

Example Usage: crunch 8 8
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 | aircrack-ng -b
00:11:22:33:44:55 -w - capture.cap

 John the Ripper

Command: crunch 8 8
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 | john --stdin
[hash_file]

Explanation:

• This command generates passwords of length 8 and pipes them directly into John the Ripper for cracking specified hashes.

Example Usage: crunch 8 8
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 | john --stdin
hashes.txt

 Hashcat

Command:crunch 8 8
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 | hashcat -m
[hash_type] -a 0 [hash_file] -

Explanation:

• This command generates passwords of length 8 and uses them in a straight dictionary attack against the specified hash type without saving them to a file.

Example Usage: crunch 8 8
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 | hashcat -m 0
-a 0 hashes.txt -

 THC-Hydra

Command: crunch 8 8
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 | hydra -l
[username] -P - [protocol] [target]

Explanation:

• This command generates passwords and pipes them directly into THC-Hydra for brute force attacks on various protocols.

Example Usage: crunch 8 8
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 | hydra -l admin
-P - ssh://192.168.1.1

 

Conclusion

In summary, crunch is a powerful tool for generating custom wordlists tailored to your password cracking needs. Its versatility allows you to create lists with specific character sets, lengths, and patterns, enhancing your efficiency in security assessments.

By mastering crunch commands, you can streamline your workflow and improve your effectiveness in penetration testing. Always remember to use these tools ethically and with permission. With practice, you can leverage crunch to boost your skills in cybersecurity.