Endpoint Segregation for Cross-Site Scripting Defense

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Solution Overview

Problem

Traditional approaches to preventing cross-site scripting attacks, such as output encoding and input filtering, are inadequate due to scalability issues and the constant creation of new attacks, and Content Security Policy (CSP) mechanisms still leave security vulnerabilities exposed.

Innovation Solution

An endpoint segregation system is implemented, where static and active content are isolated and served from separate endpoint servers, with a filtering pipe that filters suspect parameters before passing them to active content methods, ensuring that only authorized sources execute active content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional input filtering or output encoding is used to prevent cross-site scripting attacks, then security is improved, but scalability and adaptability to new attack types deteriorate

Engineering Contradiction:

ImprovesecurityVSAvoidadaptability to new attacks

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent segments the web application into multiple isolated endpoints: a static content endpoint that serves HTML pages and an active content endpoint that serves JavaScript files. This segmentation prevents cross-site scripting attacks by ensuring that malicious scripts injected into static content cannot be executed, as the active content endpoint only serves authorized JavaScript files that it generates itself.

Inventive Principle:

Principle #1Segmentation

2Reliability

If whitelist filtering is applied at data entry points, then security is improved, but scalability to large applications deteriorates

Engineering Contradiction:

ImprovesecurityVSAvoidscalability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The active content endpoint serves multiple functions: it generates JavaScript files dynamically, serves them to clients, and enforces security policies. This universal approach eliminates the need for separate filtering mechanisms at various data entry points, as all active content passes through this single controlled endpoint, making the system scalable to large applications.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If content security policy is implemented with a whitelist of valid sources, then security is improved, but vulnerability to sophisticated attacks deteriorates

Engineering Contradiction:

ImprovesecurityVSAvoidsecurity vulnerabilities

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The active content endpoint acts as an intermediary between the static content endpoint and the client. It receives requests for JavaScript files, validates them against security policies, generates or retrieves authorized JavaScript content, and serves it to the client. This intermediary layer adds a security checkpoint that prevents sophisticated attacks while maintaining the CSP whitelist mechanism.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10044728B1Endpoint segregation to prevent scripting attacks

Publication Date: 2018.08.07 AMAZON TECH INC

AI summary

A secure and efficient technique to prevent cross-site scripting attacks based on segregating the content within a given content page among independent endpoints, or servers, where static content is provided from one endpoint and active content is provided from another endpoint. Together, the different endpoints make up an endpoint segregation system. Further, security features of HTTP/HTML are used to restrict sources from which active content may be executed according to the division of static and active content among the endpoints of the endpoint segregation system.