Mitigating Open Redirect Vulnerabilities in a Node.js Application Using Express and JWT
I've searched everywhere and can't find a clear answer. Does anyone know how to Hey everyone, I'm running into an issue that's driving me crazy. I'm working on a project and hit a roadblock. I'm working on a project and hit a roadblock. I'm currently working on a Node.js application using the Express framework, and I've come across an open redirect vulnerability in my user authentication flow. The issue arises when I allow users to specify a redirect URL after login via a query parameter. I want to ensure that the redirect only goes to trusted domains, but I'm not certain about the best approach to validate these domains. Here’s a snippet of my current code where I handle the redirect: ```javascript app.post('/login', (req, res) => { const { username, password, redirectUrl } = req.body; // Assume user authentication logic here... const token = jwt.sign({ username }, 'secretKey'); res.redirect(redirectUrl ? redirectUrl : '/home'); }); ``` I’ve tried implementing a simple whitelisting approach: ```javascript const allowedDomains = ['https://myapp.com', 'https://anothertrusted.com']; const isValidRedirect = (url) => { const parsedUrl = new URL(url); return allowedDomains.includes(parsedUrl.origin); }; ``` I then incorporated this check in the redirect logic: ```javascript if (redirectUrl && isValidRedirect(redirectUrl)) { res.redirect(redirectUrl); } else { res.redirect('/home'); } ``` However, I'm still concerned about edge cases, like if the user manipulates the `redirectUrl` by encoding it or if they attempt to use a subdomain. I tested it by entering `https://malicious.com`, and it worked without any redirection validation. What is a more robust way to handle this scenario? Are there any libraries or best practices that can help secure against open redirect vulnerabilities in this context? I'm working on a CLI tool that needs to handle this. Any help would be greatly appreciated! This is part of a larger service I'm building. Any help would be greatly appreciated! The project is a mobile app built with Javascript. Thanks, I really appreciate it!