What is Weak Password Reset Implementation – Token Leakage via Host Header Poisoning vulnerability?

Weak Password Reset Implementation – Token Leakage via Host Header Poisoning Vulnerability is a critical security issue that can have severe consequences for web applications and their users. This vulnerability arises when a web application improperly handles password reset tokens and fails to validate the host header correctly. In such cases, an attacker can manipulate the host header to leak password reset tokens and gain unauthorized access to user accounts. This article will explore the vulnerability in-depth and provide sample code snippets in various popular frameworks and programming languages to help developers understand and mitigate the risk.

How the Vulnerability Works

1. User Requests Password Reset: The user initiates a password reset process by providing their email address.
2. Token Generation: The application generates a unique password reset token and associates it with the user’s email address. This token is usually a long, random string.
3. Email Sent to User: The application sends an email to the user’s provided email address, containing a link with the password reset token as a parameter.
4. User Clicks the Link: When the user clicks the link in the email, the application receives an HTTP request with the password reset token as a parameter.
5. Token Validation: The application validates the token and resets the user’s password if the token is valid.

The Vulnerability

The vulnerability arises when the application does not validate the host header properly. An attacker can manipulate the host header in their request to trick the application into thinking the request is coming from a different domain. Here’s a simplified example of how this attack can be executed:

GET /reset?token=your-reset-token HTTP/1.1
Host: attacker.com

In this example, the attacker changes the Host header to “attacker.com,” even though the email link pointed to the legitimate application domain. If the application does not properly validate the host header, it may proceed with the password reset process, assuming the request is legitimate.

Mitigation

To mitigate this vulnerability, developers should implement strict host header validation. Ensure that the Host header in the incoming request matches the expected domain. Here’s an example in various popular programming languages and frameworks:

Python (Flask)

from flask import Flask, request, abort

app = Flask(__name__)

@app.route('/reset', methods=['GET'])
def reset_password():
    expected_host = 'yourapp.com'
    if request.headers.get('Host') != expected_host:
        abort(400, 'Invalid host header')

    # Continue with password reset logic
    # ...

Node.js (Express)

const express = require('express');
const app = express();

app.get('/reset', (req, res) => {
    const expectedHost = 'yourapp.com';
    if (req.headers.host !== expectedHost) {
        res.status(400).send('Invalid host header');
        return;
    }

    // Continue with password reset logic
    // ...
});

PHP (Laravel)

use Illuminate\Http\Request;

Route::get('/reset', function (Request $request) {
    $expectedHost = 'yourapp.com';
    if ($request->header('Host') !== $expectedHost) {
        abort(400, 'Invalid host header');
    }

    // Continue with password reset logic
    // ...
});

Implementing host header validation ensures that the password reset process only proceeds when the request comes from the expected domain, preventing attackers from exploiting this vulnerability.

In conclusion, Weak Password Reset Implementation – Token Leakage via Host Header Poisoning Vulnerability can be a serious security threat if not properly addressed. Developers must understand the vulnerability and implement robust validation mechanisms to protect their applications and users from potential attacks.