testing-for-open-redirect-vulnerabilities

Identify redirect parameters like next, url, redirect, and return_uri in application endpoints, then submit external URLs as values and observe whether the server issues a 301/302 redirect to the attacker-controlled domain. Use Burp Suite to intercept requests and confirm redirect behavior.

Common bypasses include protocol-relative URLs (//evil.com), userinfo abuse (https://target.com@evil.com), URL and double URL encoding, subdomain confusion (target.com.evil.com), null byte injection, and CRLF injection. These exploit inconsistencies in how applications parse and validate URLs.

Yes, an open redirect on a trusted domain can be used as the redirect_uri in an OAuth authorization flow, causing authorization codes or access tokens to be sent to an attacker-controlled server. This is one of the highest-impact exploitation chains for open redirects.

OpenRedireX automates payload-based testing, nuclei provides open redirect detection templates, gf extracts redirect parameters from URL lists, and ffuf fuzzes parameters at scale. Burp Suite and OWASP ZAP also include passive and active redirect detection.

Applications often validate redirect destinations against allowlists or check for external domains. Try encoding the payload, using protocol-relative URLs, abusing the @ userinfo syntax, or appending the trusted domain as a subdomain or path fragment to bypass weak validation logic.

Open redirect testing is only legal on systems you own or have explicit written authorization to test. Unauthorized testing may violate computer fraud laws. This Skill is intended for authorized security assessments and educational purposes only.