TC: Medium: Securing JavaScript Web Applications via Staged Policy Enforcement

JavaScript是现代互联网计算的通用语言。与传统代码不同，JavaScript具有高度的动态性和可延展性。虽然在操作银行信息和社保号码等敏感信息的安全关键型应用程序中越来越多地使用Java脚本，但Web浏览器对Java脚本的沙箱机制(“同源策略”)太粗糙，无法充分保护“mashup”的安全，这些“mashup”在运行时组合来自相互不信任的来源的代码。该项目提供工具，通过执行由开发人员和用户编写的安全策略来保护JavaScript应用程序免受错误或恶意代码的攻击，这些安全策略指定应该信任哪些代码以及必须保护哪些数据。面对像mashup这样的动态应用程序，传统的强制执行机制在添加代码时要么需要一次不完整的初始分析，要么需要昂贵的从头开始重新分析。相反，该项目引入了阶段性程序分析。在每个阶段，尽可能多地执行已知代码的分析；分析计算的其余部分被推迟，直到有更多的代码可用。该系统在浏览器中实现并在真实的Web站点上进行评估，必须具有足够的可伸缩性以用于复杂、流行的站点；足够精确以产生较少的误报；足够高效地在最终用户的浏览器上运行而不会明显降低性能；并且在最大限度地减少用户干预和提供受保护站点的真实再现方面对用户友好。对于用户而言，该项目将使Web 2.0应用程序更加安全可靠，而不会降低浏览体验。对于开发人员来说，它将为动态Web 2.0应用程序提供早期错误检测和安全执行的保证。

JavaScript is the lingua franca of modern Internet computing. Unlike traditional code, JavaScript is highly dynamic and malleable. While JavaScript is increasingly used in security-critical applications that manipulate sensitive information like banking information and social security numbers, Web browsers' sandboxing mechanism for JavaScript (the "same-origin policy") is too coarse to adequately secure "mashups" that combine code at runtime from mutually distrusting origins.This project provides tools to secure JavaScript applications from buggy or malicious code by enforcing security policies, written by developers and users, that specify what code should be trusted and what data must be protected.Faced with dynamic applications like mashups, traditional enforcement mechanisms call for either one incomplete initial analysis or expensive from-scratch re-analysis whenever code is added. This project instead introduces staged program analysis. At each stage, as much analysis as possible is performed as possible given the known code; the remainder of the analysis computation is deferred until more code becomes available.The system, implemented in a browser and evaluated on real Web sites, must be scalable enough to use with complex, popular sites; precise enough to produce few false positives; efficient enough to run on end users' browsers without noticeable performance degradation; and user-friendly in minimizing user intervention and providing a faithful rendition of protected sites.For users, the project will make Web 2.0 applications safer and more reliable, without degrading the browsing experience. For developers, it will provide early error detection and the guarantee of safe execution for dynamic Web 2.0 applications.