Sub Resource Integrity Attribute Missing

The 'Sub Resource Integrity Attribute Missing' vulnerability occurs when your web application includes external resources, such as scripts and stylesheets, without verifying their integrity. Attackers can exploit this by manipulating or injecting malicious code into these resources, leading to potential security breaches. In this step-by-step guide, we will walk you through the process of fixing this vulnerability in your web application.

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Step 1: Understand Sub Resource Integrity (SRI)

Sub Resource Integrity (SRI) is a security feature that allows you to ensure the integrity and authenticity of external resources, such as scripts and stylesheets, before allowing them to be executed or applied. It works by generating a hash of the resource content and comparing it to the hash provided in the HTML. If they match, the resource is considered safe and can be loaded.

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Step 2: Identify Vulnerable Resources

The first step is to identify the resources in your web application that lack the SRI attribute. These resources could include third-party scripts, stylesheets, fonts, or other assets that are loaded from external sources.

For example, you might have a script tag like this:

<script src="https://example.com/js/external-script.js"></script>

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Step 3: Generate SRI Hashes

Next, you need to generate SRI hashes for each of the external resources you identified in the previous step. There are various online tools available that can help you generate these hashes. For instance, you can use the integrity attribute generator provided by SRI Hash Generator (https://www.srihash.org/).

For the script tag mentioned earlier, you would generate an SRI hash like this:

sha256-ABCDEFGHIJ1234567890KLMNOPQRSTUVWXYZ

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Step 4: Update HTML with SRI Attributes

Now it's time to update your HTML to include the SRI attribute for each vulnerable resource. Modify your resource tags to include both the src and integrity attributes.

<script src="https://example.com/js/external-script.js" integrity="sha256-ABCDEFGHIJ1234567890KLMNOPQRSTUVWXYZ"></script>

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Step 5: Cross-Origin Considerations

‍When implementing SRI, it's important to note that the hashes are sensitive to changes in the resource content. If the external resource changes, even slightly, the hash will no longer match, and the browser will refuse to load it. This can have unintended consequences, especially if you are relying on third-party resources that update frequently. In such cases, you might need to periodically update the SRI hashes.

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Step 6: Test Your Application

‍After implementing SRI for the vulnerable resources, thoroughly test your web application. Check if the application behaves as expected and if all the external resources are loading without any issues. Look for any console errors related to the SRI attribute.

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Step 7: Monitor for Changes

‍Regularly monitor the external resources that you have secured with SRI. If any of these resources change or are updated, you will need to generate new SRI hashes and update your application's HTML accordingly.

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Step 8: Automate the Process

To streamline the process of maintaining SRI hashes for your web application, consider automating the generation and update of SRI attributes. This can be achieved using build tools or scripts that generate the necessary hashes during your deployment process.

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Conclusion:

‍By following these step-by-step instructions, you can effectively fix the 'Sub Resource Integrity Attribute Missing' vulnerability in your web application. Implementing Sub Resource Integrity adds an extra layer of security by ensuring that the external resources your application relies on are not tampered with, reducing the risk of malicious attacks. Stay vigilant and keep your application's security measures up-to-date to protect your users and their data.

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