Browser Defense Agent Mitigating Cross-Site Scripting via Service Workers
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Solution Overview
Problem
Current solutions, such as anti-virus and anti-malware, are ineffective in protecting web browsers from client-side cross-site scripting exploitation attacks like Megacart, which inject malicious JavaScript to steal personal information, as they are not designed to handle zero-day attacks and cannot prevent information leakage from user devices.
Innovation Solution
A defense agent is installed on web browsers to detect and mitigate cross-site scripting exploitation attacks by communicating with a backend server, using a whitelist to block unauthorized access to external resources and hardening scripts through JavaScript API modification and service workers to intercept and approve only legitimate requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anti-virus or anti-malware solutions are used to protect client devices, then device security is improved, but they cannot prevent information leakage from user devices against zero-day attacks
Solution Approach 1:
The patent introduces a service worker as an intermediary layer between the web page scripts and the browser's external resource access mechanisms. This service worker intercepts all requests from scripts attempting to access external resources (such as form data submissions) and validates them against a whitelist of authorized domains. By positioning this intermediary, the system blocks malicious zero-day scripts from exfiltrating information while allowing legitimate third-party services to function, thus preventing information leakage without compromising device security.
2Reliability
If current anti-virus solutions learn signatures of viruses before blocking them, then malware protection is improved, but they are ineffective against zero-day attacks with no prior signatures
Solution Approach 1:
The patent implements preliminary action by establishing a whitelist of authorized external resources before any web page execution occurs. The service worker is installed and configured in advance with knowledge of legitimate third-party service domains. When a web page loads, the service worker is already in position to intercept and validate script requests against this pre-established whitelist. This preliminary configuration enables the system to immediately block zero-day attacks without requiring prior signature learning, as the validation mechanism is proactive rather than reactive.
3Adaptability or versatility
If third-party servers supply code to websites, then website functionality is improved, but compromise of one third-party server can breach thousands of sites simultaneously
Solution Approach 1:
The patent implements feedback by creating a closed-loop validation system where the service worker continuously monitors and validates all external resource requests made by web page scripts. Each request is checked against the whitelist, and the outcome (allow or block) is enforced immediately. This feedback mechanism ensures that even if a third-party server is compromised and begins serving malicious code, the malicious requests will be detected and blocked by the service worker's validation logic, preventing cross-site scripting exploitation while maintaining legitimate third-party functionality.
Data Source
AI summary
A method and system for detecting client-side cross-site scripting exploitation attacks according to an embodiment are disclosed. The method includes downloading an access list from a remote server; capturing a request to access an external resource, wherein the request is initiated by a script executed over the web browser, wherein the external web resource is external to the web browser executed on a client device; determining, based on the access list, if the requested external web resource can be accessed; and applying a mitigation action on the request to access the external web resource when it is determined that the external web resource cannot be accessed.