Blog | G5 Cyber Security

PHP Password Bypass: Simple Fix

TL;DR

This guide shows how to quickly disable password authentication in a basic PHP application for testing or development purposes. Warning: This is insecure and should only be used in controlled environments!

Steps

  1. Locate the Authentication Code
  2. Find the section of your PHP code that handles user login. It will typically involve checking a username and password against stored credentials.

  3. Comment Out or Remove Password Check
  4. The simplest way to bypass password authentication is to comment out or delete the lines of code responsible for verifying the password. For example, if your code looks like this:

    if ($password == $stored_hash) {
        // Login successful
    } else {
        // Login failed
    }

    Change it to:

    // if ($password == $stored_hash) {
    //     Login successful
    // } else {
    //     Login failed
    // }
    
    // Always log the user in for testing.
    

    Or, more directly:

    $login_successful = true; // Bypass password check. DO NOT USE IN PRODUCTION!
  5. Ensure Login Success
  6. Modify the code to always set a successful login flag. This might involve setting a session variable or redirecting the user.

    session_start();
    $_SESSION['user_id'] = 1; // Example: Log in as user ID 1.
    header('Location: welcome.php');
  7. Test the Bypass
  8. Refresh your login page and attempt to log in with any username (and any password). You should now be logged in without entering a correct password.

  9. Important Security Note
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