What is Open Redirect?

Open Redirect is a web vulnerability that happens when a website allows users to be redirected to another site without properly checking or validating the destination URL.
xample:

Suppose a link on a website looks like this:
https://example.com/redirect?url=http://badsite.com

If the site directly sends users to http://badsite.com without checking, it’s called an open redirect.

Why It’s Dangerous:

• Attackers can trick users into clicking a trusted-looking link that sends them to a malicious site (for phishing, malware, etc.).
• Can be used to bypass security filters or steal user data.

How to Prevent It:

• Only allow redirects to trusted, whitelisted URLs.
• Avoid using user input directly in redirects.
• Use relative paths instead of full external URLs.

How to find Open Redirect?

Look for URL Parameters Used for Redirection
?url=
?redirect=
?next=
?dest=
?continue=
?return=

Example:
https://example.com/login?next=http://malicious.com

2. Modify the URL with an External Link

Try changing the value to a site you control (or a harmless site like https://google.com) and see if the browser redirects you:
https://example.com/login?next=https://google.com

If you click the link and it takes you to Google, it’s vulnerable.

Try Bypassing Basic Protections

Some apps may block full URLs, but allow tricky ones. Test these variations:

//malicious.com
https:\malicious.com
///malicious.com
%2f%2fmalicious.com (URL-encoded)

4. Use Tools

You can automate the discovery using tools like:

• Burp Suite (intercept and modify redirects)
• Open Redirect Scanner (in some recon frameworks like OWASP ZAP)
• Google Dorks for known redirect patterns

Easy Way to find Open Redirction!!

Quick 3-Step Method

✅ 1. Find URLs with redirect-like parameters

Look for links like:

perlCopyEdithttps://example.com/page?redirect=
https://example.com/login?next=

These parameters often control where the site redirects you after an action.

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✅ 2. Change the parameter to an external site

Replace the parameter value with something like:

perlCopyEdithttps://example.com/login?next=https://google.com

Then open the URL in your browser.

• If it takes you directly to Google, that’s a red flag.
• Try it with your own site or a test URL you control.

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✅ 3. Try variations if blocked

If the redirect fails, try these tricks:

• URL-encoded: perlCopyEdit?next=https%3A%2F%2Fgoogle.com
• Double slashes: perlCopyEdit?next=//google.com
• Backslashes or mixed slashes: luaCopyEdit?next=\google.com

If any version results in an external redirect, it’s likely vulnerable.

Conclusion of Open Redirect

Open Redirect is a web vulnerability where a website redirects users to external URLs without proper validation. While often considered low-risk, it can be dangerous when combined with phishing, malware distribution, or social engineering.

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🔑 Key Points:

• It exploits parameters like ?url=, ?redirect=, or ?next=.
• Attackers can use it to trick users into trusting malicious links.
• It may bypass security filters or aid in credential theft.
• It is easy to find and fix, but often overlooked.

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🔒 Mitigation:

• Only allow redirects to whitelisted URLs.
• Avoid using user input in redirects when possible.
• Use relative paths instead of full URLs.