Publications

2014
J. Mickens, “Pivot: Fast, Synchronous Mashup Isolation Using Generator Chains,” in IEEE Symposium on Security and Privacy, San Jose, CA, 2014. PaperAbstract

Pivot is a new JavaScript isolation framework for web applications. Pivot uses iframes as its low-level isolation containers, but it uses code rewriting to implement synchronous cross-domain interfaces atop the asynchronous cross-frame postMessage() primitive. Pivot layers a distributed scheduling abstraction across the frames, essentially treating each frame as a thread which can invoke RPCs that are serviced by external threads. By rewriting JavaScript call sites, Pivot can detect RPC invocations; Pivot exchanges RPC requests and responses via postMessage(), and it pauses and restarts frames using a novel rewriting technique that translates each frame’s JavaScript code into a restartable generator function. By leveraging both iframes and rewriting, Pivot does not need to rewrite all code, providing an order-of-magnitude performance improvement over rewriting-only solutions. Compared to iframe-only approaches, Pivot provides synchronous RPC semantics, which developers typically prefer over asynchronous RPCs. Pivot also allows developers to use the full, unrestricted JavaScript language, including powerful statements like eval().

2013
J. R. Lorch, B. Parno, J. Mickens, M. Raykova, and J. Schiffman, “Shroud: Ensuring Private Access to Large-Scale Data in the Data Center,” in FAST, San Jose, CA, 2013. PaperAbstract

Recent events have shown online service providers the perils of possessing private information about users. Encrypting data mitigates but does not eliminate this threat: the pattern of data accesses still reveals information. Thus, we present Shroud, a general storage system that hides data access patterns from the servers running it, protecting user privacy. Shroud functions as a virtual disk with a new privacy guarantee: the user can look up a block without revealing the block’s address. Such a virtual disk can be used for many purposes, including map lookup, microblog search, and social networking.

Shroud aggressively targets hiding accesses among hundreds of terabytes of data. We achieve our goals by adapting oblivious RAM algorithms to enable large-scale parallelization. Specifically, we show, via new techniques such as oblivious aggregation, how to securely use many inexpensive secure coprocessors acting in parallel to improve request latency. Our evaluation combines large-scale emulation with an implementation on secure coprocessors and suggests that these adaptations bring private data access closer to practicality.

2012
K. Lin, D. Chu, J. Mickens, L. Zhuang, F. Zhao, and J. Qiu, “Gibraltar: Exposing Hardware Devices to Web Pages Using AJAX,” in USENIX WebApps, Boston, MA, 2012. PaperAbstract

Gibraltar is a new framework for exposing hardware devices to web pages. Gibraltar’s fundamental insight is that JavaScript’s AJAX facility can be used as a hardware access protocol. Instead of relying on the browser to mediate device interactions, Gibraltar sandboxes the browser and uses a small device server to handle hardware requests. The server uses native code to interact with devices, and it exports a standard web server interface on the localhost. To access hardware, web pages send device commands to the server using HTTP requests; the server returns hardware data via HTTP responses.

Using a client-side JavaScript library, we build a simple yet powerful device API atop this HTTP transfer protocol. The API is particularly useful to developers of mobile web pages, since mobile platforms like cell phones have an increasingly wide array of sensors that, prior to Gibraltar, were only accessible via native code plugins or the limited, inconsistent APIs provided by HTML5. Our implementation of Gibraltar on Android shows that Gibraltar provides stronger security guarantees than HTML5; furthermore, it shows that HTTP is responsive enough to support interactive web pages that perform frequent hardware accesses. Gibraltar also supports an HTML5 compatibility layer that implements the HTML5 interface but provides Gibraltar’s stronger security.

J. Mickens and M. Finifter, “Jigsaw: Efficient, Low-effort Mashup Isolation,” in USENIX WebApps, Boston, MA, 2012. PaperAbstract

A web application often includes content from a variety of origins. Securing such a mashup application is challenging because origins often distrust each other and wish to expose narrow interfaces to their private code and data. Jigsaw is a new framework for isolating these mashup components. Jigsaw is an extension of the JavaScript language that can be run inside standard browsers using a Jigsaw-to-JavaScript compiler. Unlike prior isolation schemes that require developers to specify complex, error-prone policies, Jigsaw leverages the well-understood public/private keywords from traditional object-oriented languages, making it easy for a domain to tag internal data as externally visible. Jigsaw provides strong iframe-like isolation, but unlike previous approaches that use actual iframes as isolation containers, Jigsaw allows mutually distrusting code to run inside the same frame; this allows scripts to share state using synchronous method calls instead of asynchronous message passing. Jigsaw also introduces a novel encapsulation mechanism called surrogates. Surrogates allow domains to safely exchange objects by reference instead of by value. This improves sharing efficiency by eliminating cross-origin marshaling overhead.

J. Mickens, “Rivet: Browser-agnostic Remote Debugging for Web Applications,” in USENIX ATC, Boston, MA, 2012. PaperAbstract

Rivet is the first fully-featured, browser-agnostic remote debugger for web applications. Using Rivet, developers can inspect and modify the state of live web pages that are running inside unmodified end-user web browsers. This allows developers to explore real application bugs in the context of the actual machines on which those bugs occur. To make an application Rivet-aware, developers simply add the Rivet JavaScript library to the client-side portion of the application. Later, when a user detects a problem with the application, the user informs Rivet; in turn, Rivet pauses the application and notifies a remote debug server that a debuggable session is available. The server can launch an interactive debugger front-end for a human developer, or use Rivet’s live patching mechanism to automatically install a fix on the client or run diagnostics for offline analysis. Experiments show that Rivet imposes negligible overhead during normal application operation. At debug time, Rivet’s network footprint is small, and Rivet is computationally fast enough to support non-trivial diagnostics and live patches.

2011
J. Mickens and M. Dhawan, “Atlantis: Robust, Extensible Execution Environments for Web Applications,” in SOSP, Cascais, Portugal, 2011. PaperAbstract

Today’s web applications run inside a complex browser environment that is buggy, ill-specified, and implemented in different ways by different browsers. Thus, web applications that desire robustness must use a variety of conditional code paths and ugly hacks to deal with the vagaries of their runtime. Our new exokernel browser, called Atlantis, solves this problem by providing pages with an extensible execution environment. Atlantis defines a narrow API for basic services like collecting user input, exchanging network data, and rendering images. By composing these primitives, web pages can define custom, high-level execution environments. Thus, an application which does not want a dependence on Atlantis’ predefined web stack can selectively redefine components of that stack, or define markup formats and scripting languages that look nothing like the current browser runtime. Unlike prior microkernel browsers like OP, and unlike compile-to-JavaScript frameworks like GWT, Atlantis is the first browsing system to truly minimize a web page’s dependence on black box browser code. This makes it much easier to develop robust, secure web applications.

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