Multiple X-Frame-Options Header Entries

The X-Frame-Options header is an HTTP response header that tells the browser whether or not to allow a web page to be displayed inside a frame or iframe. It is designed to protect web applications from clickjacking attacks where an attacker tries to trick a user into clicking on a hidden button or link by overlaying it with an invisible frame or iframe. The header can have three values: DENY, SAMEORIGIN, and ALLOW-FROM.

The 'Multiple X-Frame-Options Header Entries' vulnerability occurs when a web application sends multiple X-Frame-Options headers with different values in the response. This can happen when the application uses multiple frameworks or libraries that set the header independently or when there are conflicting configurations.

To fix this vulnerability, you need to ensure that your application sends only one X-Frame-Options header with the correct value in the response. Here is a step-by-step guide on how to fix the 'Multiple X-Frame-Options Header Entries' vulnerability:

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Step 1: Identify the conflicting headers

The first step is to identify which headers are conflicting and causing the issue. You can use a tool like Burp Suite or OWASP ZAP to intercept and analyze the HTTP response headers. Look for the X-Frame-Options header and see if there are multiple entries with different values. Note down the values of each header entry.

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Step 2: Determine the correct header value

The next step is to determine the correct value for the X-Frame-Options header. The value depends on your application's requirements and can be set to one of the following:

• DENY: This value instructs the browser not to display the web page in a frame or iframe under any circumstances.
• SAMEORIGIN: This value allows the web page to be displayed in a frame or iframe only if the parent frame or iframe is from the same origin as the web page.
• ALLOW-FROM uri: This value allows the web page to be displayed in a frame or iframe only if the parent frame or iframe is from the specified URI.

Choose the value that best suits your application's needs.

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Step 3: Remove conflicting headers

Remove all conflicting X-Frame-Options headers from your application's response. You can do this by modifying your application's code or configuration files. Look for all instances where the X-Frame-Options header is being set and remove any duplicate entries.

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Step 4: Set the correct header value

Set the X-Frame-Options header with the correct value in the response. You can do this by modifying your application's code or configuration files. Here are some examples of how to set the header in different programming languages:

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response.setHeader("X-Frame-Options", "SAMEORIGIN");

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header("X-Frame-Options: SAMEORIGIN");

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Response.AddHeader("X-Frame-Options", "SAMEORIGIN");

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res.setHeader("X-Frame-Options", "SAMEORIGIN");

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Step 5: Test the fix

Once you have made the necessary changes, test your application to ensure that the vulnerability has been fixed. Use an external vulnerability scanner or a tool like Burp Suite to verify that the application is sending only one X-Frame-Options header with the correct value in the response.

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Conclusion:

The 'Multiple X-Frame-Options Header Entries' vulnerability can leave your web application vulnerable to clickjacking attacks. To fix this vulnerability, you need to identify conflicting headers, determine the correct header value, remove conflicting headers, set the correct header value, and test the fix. By following these steps, you can ensure that your application is protected from clickjacking attacks.

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