# Open redirect ## What is it? An Open Redirect Vulnerability allows an attacker to redirect a user to an arbitrary website of the attacker's choosing. It occurs when an application incorporates user-supplied data into a URL which causes a redirection to that URL. This can be used to facilitate phishing attacks, steal sensitive information, or perform other malicious activities. **A simple example** Consider a website that uses a URL parameter to redirect the user to a specified page. For example: . An attacker could replace "" with a malicious site, then trick a user into following the crafted link. Open Redirects can lead to: Phishing attacks Disclosure of sensitive information Malware installation Execution of arbitrary scripts Other learning resources: OWASP: PortSwigger: ## **Checklist** * [ ] Does the application use redirection functions that include user-supplied input? * [ ] Are redirects implemented without validation of the target URL? * [ ] Can an attacker manipulate the redirection URL to point to an arbitrary domain? * [ ] Does the application append user-supplied input into the URL causing the redirection? ## Exploitation Craft an URL with redirection to a malicious site ``` http://website.com/redirect?site=http://malicious-site.com ``` Trick the user into clicking the link ``` "You've won a prize! Click here to claim: http://website.com/redirect?site=http://malicious-site.com" ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://appsecexplained.gitbook.io/appsecexplained/common-vulns/open-redirect.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.