// Vulnerable code example (simplified from Juice Shop source) app.post('/api/image/uploads', (req, res) => const imageUrl = req.body.url; // No validation of the URL scheme or domain request.get(imageUrl, (error, response, body) => if (error) res.status(400).send('Failed to fetch image'); else // Process the image... res.send('Image uploaded');
POST /api/image/uploads HTTP/1.1 Host: juice-shop.local Content-Type: application/json "url": "http://localhost:3000/some/path" juice shop ssrf
http://localhost:3000/solve/challenge/ssrf // Vulnerable code example (simplified from Juice Shop
); );
Or more classically: The functionality, where you provide a URL to an image of your broken juice. The server tries to fetch that image to validate it. The Vulnerability: Unvalidated URL Fetching Let's look at the pseudo-code of the vulnerable endpoint: The Vulnerability: Unvalidated URL Fetching Let's look at
Introduction: The Silent Proxy Server-Side Request Forgery (SSRF) is often called the "forgotten twin" of Cross-Site Request Forgery (CSRF). While CSRF tricks a user's browser , SSRF tricks the server itself . An SSRF vulnerability allows an attacker to induce the server to make HTTP requests to an arbitrary domain of the attacker's choosing.
const dns = require('dns').promises; const ip = await dns.lookup(urlObj.hostname); if (isPrivateIP(ip.address)) throw new Error('Blocked'); The SSRF vulnerability in OWASP Juice Shop is small but elegant. It demonstrates a single line of missing validation leading to a complete breach of network segmentation. For penetration testers, mastering SSRF means understanding that the server is just another user—one with far more privileges.