Hydra: Brute Force aspx Forms

TL;DR

This guide shows you how to use Hydra to attempt brute-force attacks against ASPX form logins. Warning: Attempting to crack passwords without permission is illegal and unethical. This information is for educational purposes only.

Prerequisites

• Hydra installed (see the official GitHub repository).
• A target ASPX form login URL.
• A wordlist containing potential usernames and passwords.

Step 1: Identify the Form Parameters

You need to know the names of the username and password fields in the HTML form. Use your browser’s developer tools (usually by pressing F12) to inspect the source code of the login page.

• Right-click on the login form and select ‘Inspect’.
• Look for the input fields with name attributes. These are the parameters Hydra will use. Common names include: username, user, login, password, pass, etc.

Step 2: Basic Hydra Command

Here’s a basic command structure to start a brute-force attack:

hydra -l  -P   http-post-form "username=&password="

• -l : The username to attempt. If you want to brute force usernames as well, use a wordlist for this too (see Step 4).
• -P : Path to the file containing potential passwords, one password per line.
• : The URL of the ASPX login page.
• http-post-form: Specifies that we’re using an HTTP POST form submission method.
• “username=&password=“: Defines the form parameters and their names as identified in Step 1. Replace and with the actual parameter names from the HTML source code.

Example:

hydra -l testuser -P /usr/share/wordlists/rockyou.txt http://example.com/login.aspx http-post-form "username=uname&password=pwd"

Step 3: Understanding the Output

Hydra will output its attempts to the console. Look for lines that indicate a successful login:

• [STATUS]: Shows the current status of the attack (e.g., ‘1 task started’, ‘0 tasks running’).
• [LOGIN]: This line indicates a successful login attempt, displaying the username and password that worked.

Step 4: Brute-forcing Both Username and Password

To brute-force both usernames and passwords, use two wordlists:

hydra -l  -P   http-post-form "username=&password="

• -l : Path to the file containing potential usernames.

Example:

hydra -l /usr/share/wordlists/usernames.txt -P /usr/share/wordlists/rockyou.txt http://example.com/login.aspx http-post-form "username=uname&password=pwd"

Step 5: Using a Proxy (Optional)

If you need to use a proxy for anonymity or to bypass restrictions, add the -o : option:

hydra -l testuser -P /usr/share/wordlists/rockyou.txt http://example.com/login.aspx http-post-form "username=uname&password=pwd" -o 127.0.0.1:8080

Step 6: Limiting the Number of Attempts

To prevent excessive attempts, use the -t option to limit the number of concurrent connections:

hydra -l testuser -P /usr/share/wordlists/rockyou.txt http://example.com/login.aspx http-post-form "username=uname&password=pwd" -t 16

Important Considerations

• Rate Limiting: Many websites implement rate limiting to prevent brute-force attacks. Adjust the number of threads (-t) accordingly.
• Account Lockout: Repeated failed login attempts may lock an account.
• Legal Implications: Always obtain explicit permission before attempting any security testing on a system you do not own.