DOM-based XSS in Fides Privacy Platform

Executive Summary

This vulnerability is a DOM-based Cross-Site Scripting (XSS) issue found in the open-source privacy engineering platform Fides, specifically in the fides.js component. It occurs via the fides_description override in versions from 2.33.0 up to but not including 2.84.5. This means that an attacker could potentially inject malicious scripts into the web page by manipulating the fides_description, leading to execution of unauthorized code in the user's browser.

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Impact Analysis

The DOM-based XSS vulnerability can allow attackers to execute arbitrary scripts in the context of the affected web application. This can lead to unauthorized actions such as stealing user session tokens, redirecting users to malicious sites, or performing actions on behalf of the user without their consent. Since the vulnerability does not require user interaction and has a high severity score, it poses a significant security risk.

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Mitigation Strategies

To mitigate this vulnerability, upgrade Fides to version 2.84.5 or later, where the DOM-based XSS issue in fides.js via the fides_description override has been patched.

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Compliance Impact

The DOM-based XSS vulnerability in fides.js allows an attacker to execute arbitrary JavaScript within the embedding site's origin, potentially leading to data theft, request forgery, and content manipulation.

Such unauthorized access and manipulation of data can compromise the confidentiality and integrity of personal data, which are critical requirements under regulations like GDPR and HIPAA.

Therefore, if exploited, this vulnerability could lead to non-compliance with these standards due to potential breaches of personal data protection and privacy obligations.

Mitigation by patching the vulnerability or disabling HTML-formatted descriptions is necessary to maintain compliance.

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Detection Guidance

This vulnerability is a DOM-based Cross-Site Scripting (XSS) issue in the fides.js script that occurs when HTML-formatted banner descriptions are enabled and overridden via URL query parameters, JavaScript globals, or cookies.

To detect this vulnerability on your system, you should check if your deployment of Fides uses fides.js with HTML-formatted descriptions enabled (i.e., the environment variable FIDES_PRIVACY_CENTER__ALLOW_HTML_DESCRIPTION is set to true).

You can attempt to detect the vulnerability by testing if the description override parameter accepts and executes injected HTML or JavaScript payloads.

• Use a web proxy or browser developer tools to inspect the consent banner's description field for unsanitized HTML or script execution.
• Craft a URL with a malicious script payload in the description override parameter and observe if the script executes when the banner renders.
• Check cookies related to the consent banner for injected payloads that persist across sessions.

There are no specific commands provided in the resources, but manual testing with crafted URLs and inspecting the banner behavior is recommended.

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