The X Frame Options header is a response header used by web servers to control whether a browser should be allowed to display a web page inside a frame or iframe. This header is primarily used to prevent clickjacking attacks, where a malicious website embeds a legitimate website within a hidden iframe, tricking the user into clicking on something they didn’t intend to.
The X-Frame-Options header has three main values:
DENY: This option prevents the page from being displayed in a frame or iframe, regardless of where the request is coming from.
SAMEORIGIN: This option allows the page to be displayed in a frame or iframe, but only if the request is coming from the same origin (same domain).
Prevents Clickjacking: Clickjacking is a malicious practice where an attacker uses hidden or transparent iframes to trick users into clicking on something different from what they think they are clicking on. This can lead to malicious actions being taken without the user's consent. The X-Frame-Options header helps prevent such attacks.
Improved Web Security: Setting X-Frame-Options correctly can prevent attackers from embedding your website into malicious pages and tricking users into performing unintended actions.
Protects User Data: By preventing iframes from loading potentially malicious content, the X-Frame-Options header can help ensure that users’ personal data and actions are not compromised.
Meets Best Practices: Security headers like X-Frame-Options are widely considered a best practice for securing modern web applications. Properly configuring this header demonstrates a commitment to securing user interactions.
The first step in fixing X-Frame-Options issues is to ensure that your web server is correctly sending the X-Frame-Options header in its responses. This header should be set with one of the following values:
DENY: This is the most restrictive option and should be used if your website does not require embedding in iframes at all.
SAMEORIGIN: This is a more lenient option and allows your site to be embedded only within its own domain.
ALLOW-FROM uri: If you need to allow embedding from a specific domain (for instance, if you are embedding a video player or another site), use this option to specify the exact allowed domain.
2. Adding the Header to Your Server Configuration
Depending on the web server you’re using, you’ll need to configure it to send the X-Frame-Options header in the response.
Apache: You can set this header using the Header directive in your .htaccess file.
Header always set X-Frame-Options "DENY"
Nginx: You can add the following directive inside the server block of your Nginx configuration.
add_header X-Frame-Options "DENY";
IIS: For Microsoft IIS, use the HTTP Response Headers settings in the IIS Manager or edit the web.config file:
<httpProtocol>
<customHeaders>
<add name="X-Frame-Options" value="DENY" />
</customHeaders>
</httpProtocol>
3. Test for Missing or Incorrect Header
After you’ve configured the header, test whether the X-Frame-Options header is being applied correctly:
Use a tool like curl to inspect the response headers:
curl -I https://yourwebsite.com
Alternatively, you can use browser developer tools (under the "Network" tab) to inspect the response headers.
4. Handling the ALLOW-FROM Directive
If you need to use the ALLOW-FROM directive to permit specific websites to embed your page, be aware that it’s deprecated in many modern browsers (e.g., Chrome) and might not be supported. As an alternative, you could look into using Content Security Policy (CSP) headers, which offer more fine-grained control over framing content.
Example CSP header for allowing embedding from specific sources:
Content-Security-Policy: frame-ancestors 'self' https://alloweddomain.com;
5. Update Legacy Applications
If your application was built before the widespread adoption of security headers, make sure to review your code and add the X-Frame-Options header where necessary. Web applications should be kept up-to-date with modern security practices.
6. Monitor Security Headers
Regularly check for security misconfigurations, such as missing X-Frame-Options headers, using automated tools or services that analyze your website’s security. Platforms like SecurityHeaders.io provide an easy way to see your HTTP security headers.
7. Consider Content Security Policy (CSP)
If X-Frame-Options is not sufficient for your needs, consider implementing a Content Security Policy (CSP). The frame-ancestors directive in CSP is a more flexible and future-proof approach to controlling which websites can embed your content in frames or iframes.
Example: Content-Security-Policy: frame-ancestors 'self' https://example.com;
The X Frame Options header is an important security measure to prevent clickjacking and other malicious activities involving framing.
The header should be configured to one of three values: DENY, SAMEORIGIN, or ALLOW-FROM uri.
Properly configure your web server (Apache, Nginx, IIS) to include this header.
Regularly test for correct header implementation and consider using Content Security Policy (CSP) as a more advanced, flexible alternative.