Statically Checking Web API Requests in JavaScript

Many JavaScript applications perform HTTP requests to web APIs, relying on the request URL, HTTP method, and request data to be constructed correctly by string operations. Traditional compile-time error checking, such as calling a non-existent method in Java, are not available for checking whether such requests comply with the requirements of a web API. In this paper, we propose an approach to statically check web API requests in JavaScript. Our approach first extracts a request's URL string, HTTP method, and the corresponding request data using an inter-procedural string analysis, and then checks whether the request conforms to given web API specifications. We evaluated our approach by checking whether web API requests in JavaScript files mined from GitHub are consistent or inconsistent with publicly available API specifications. From the 6575 requests in scope, our approach determined whether the request's URL and HTTP method was consistent or inconsistent with web API specifications with a precision of 96.0%. Our approach also correctly determined whether extracted request data was consistent or inconsistent with the data requirements with a precision of 87.9% for payload data and 99.9% for query data. In a systematic analysis of the inconsistent cases, we found that many of them were due to errors in the client code. The here proposed checker can be integrated with code editors or with continuous integration tools to warn programmers about code containing potentially erroneous requests.Comment: International Conference on Software Engineering, 201

Hyp3rArmor: reducing web application exposure to automated attacks

Web applications (webapps) are subjected constantly to automated, opportunistic attacks from autonomous robots (bots) engaged in reconnaissance to discover victims that may be vulnerable to specific exploits. This is a typical behavior found in botnet recruitment, worm propagation, largescale fingerprinting and vulnerability scanners. Most anti-bot techniques are deployed at the application layer, thus leaving the network stack of the webapp’s server exposed. In this paper we present a mechanism called Hyp3rArmor, that addresses this vulnerability by minimizing the webapp’s attack surface exposed to automated opportunistic attackers, for JavaScriptenabled web browser clients. Our solution uses port knocking to eliminate the webapp’s visible network footprint. Clients of the webapp are directed to a visible static web server to obtain JavaScript that authenticates the client to the webapp server (using port knocking) before making any requests to the webapp. Our implementation of Hyp3rArmor, which is compatible with all webapp architectures, has been deployed and used to defend single and multi-page websites on the Internet for 114 days. During this time period the static web server observed 964 attempted attacks that were deflected from the webapp, which was only accessed by authenticated clients. Our evaluation shows that in most cases client-side overheads were negligible and that server-side overheads were minimal. Hyp3rArmor is ideal for critical systems and legacy applications that must be accessible on the Internet. Additionally Hyp3rArmor is composable with other security tools, adding an additional layer to a defense in depth approach.This work has been supported by the National Science Foundation (NSF) awards #1430145, #1414119, and #1012798

Systematic adaptation of dynamically generated source code via domain-specific examples

In modern web-based applications, an increasing amount of source code is generated dynamically at runtime. Web applications commonly execute dynamically generated code (DGC) emitted by third-party, black-box generators, run at remote sites. Web developers often need to adapt DGC before it can be executed: embedded HTML can be vulnerable to cross-site scripting attacks; an API may be incompatible with some browsers; and the program\u27s state created by DGC may not be persisting. Lacking any systematic approaches for adapting DGC, web developers resort to ad-hoc techniques that are unsafe and error-prone. This study presents an approach for adapting DGC systematically that follows the program-transformation-byexample paradigm. The proposed approach provides predefined, domain-specific before/after examples that capture the variability of commonly used adaptations. By approving or rejecting these examples, web developers determine the required adaptation transformations, which are encoded in an adaptation script operating on the generated code\u27s abstract syntax tree. The proposed approach is a suite of practical JavaScript program adaptations and their corresponding before/after examples. The authors have successfully applied the approach to real web applications to adapt third-party generated JavaScript code for security, browser compatibility, and persistence

Efficient Dynamic Access Analysis Using JavaScript Proxies

JSConTest introduced the notions of effect monitoring and dynamic effect inference for JavaScript. It enables the description of effects with path specifications resembling regular expressions. It is implemented by an offline source code transformation. To overcome the limitations of the JSConTest implementation, we redesigned and reimplemented effect monitoring by taking advantange of JavaScript proxies. Our new design avoids all drawbacks of the prior implementation. It guarantees full interposition; it is not restricted to a subset of JavaScript; it is self-maintaining; and its scalability to large programs is significantly better than with JSConTest. The improved scalability has two sources. First, the reimplementation is significantly faster than the original, transformation-based implementation. Second, the reimplementation relies on the fly-weight pattern and on trace reduction to conserve memory. Only the combination of these techniques enables monitoring and inference for large programs.Comment: Technical Repor

Securing the Next Generation Web

With the ever-increasing digitalization of society, the need for secure systems is growing. While some security features, like HTTPS, are popular, securing web applications, and the clients we use to interact with them remains difficult.To secure web applications we focus on both the client-side and server-side. For the client-side, mainly web browsers, we analyze how new security features might solve a problem but introduce new ones. We show this by performing a systematic analysis of the new Content Security Policy (CSP)\ua0 directive navigate-to. In our research, we find that it does introduce new vulnerabilities, to which we recommend countermeasures. We also create AutoNav, a tool capable of automatically suggesting navigation policies for this directive. Finding server-side vulnerabilities in a black-box setting where\ua0 there is no access to the source code is challenging. To improve this, we develop novel black-box methods for automatically finding vulnerabilities. We\ua0 accomplish this by identifying key challenges in web scanning and combining the best of previous methods. Additionally, we leverage SMT solvers to\ua0 further improve the coverage and vulnerability detection rate of scanners.In addition to browsers, browser extensions also play an important role in the web ecosystem. These small programs, e.g. AdBlockers and password\ua0 managers, have powerful APIs and access to sensitive user data like browsing history. By systematically analyzing the extension ecosystem we find new\ua0 static and dynamic methods for detecting both malicious and vulnerable extensions. In addition, we develop a method for detecting malicious extensions\ua0 solely based on the meta-data of downloads over time. We analyze new attack vectors introduced by Google’s new vehicle OS, Android Automotive. This\ua0 is based on Android with the addition of vehicle APIs. Our analysis results in new attacks pertaining to safety, privacy, and availability. Furthermore, we\ua0 create AutoTame, which is designed to analyze third-party apps for vehicles for the vulnerabilities we found

Understanding emerging client-Side web vulnerabilities using dynamic program analysis

Today's Web heavily relies on JavaScript as it is the main driving force behind the plethora of Web applications that we enjoy daily. The complexity and amount of this client-side code have been steadily increasing over the years. At the same time, new vulnerabilities keep being uncovered, for which we mostly rely on manual analysis of security experts. Unfortunately, such manual efforts do not scale to the problem space at hand. Therefore in this thesis, we present techniques capable of finding vulnerabilities automatically and at scale that originate from malicious inputs to postMessage handlers, polluted prototypes, and client-side storage mechanisms. Our results highlight that the investigated vulnerabilities are prevalent even among the most popular sites, showing the need for automated systems that help developers uncover them in a timely manner. Using the insights gained during our empirical studies, we provide recommendations for developers and browser vendors to tackle the underlying problems in the future. Furthermore, we show that security mechanisms designed to mitigate such and similar issues cannot currently be deployed by first-party applications due to their reliance on third-party functionality. This leaves developers in a no-win situation, in which either functionality can be preserved or security enforced.JavaScript ist die treibende Kraft hinter all den Web Applikationen, die wir heutzutage täglich nutzen. Allerdings ist über die Zeit hinweg gesehen die Masse, aber auch die Komplexität, von Client-seitigem JavaScript Code stetig gestiegen. Außerdem finden Sicherheitsexperten immer wieder neue Arten von Verwundbarkeiten, meistens durch manuelle Analyse des Codes. In diesem Werk untersuchen wir deshalb Methodiken, mit denen wir automatisch Verwundbarkeiten finden können, die von postMessages, veränderten Prototypen, oder Werten aus Client-seitigen Persistenzmechnanismen stammen. Unsere Ergebnisse zeigen, dass die untersuchten Schwachstellen selbst unter den populärsten Websites weit verbreitet sind, was den Bedarf an automatisierten Systemen zeigt, die Entwickler bei der rechtzeitigen Aufdeckung dieser Schwachstellen unterstützen. Anhand der in unseren empirischen Studien gewonnenen Erkenntnissen geben wir Empfehlungen für Entwickler und Browser-Anbieter, um die zugrunde liegenden Probleme in Zukunft anzugehen. Zudem zeigen wir auf, dass Sicherheitsmechanismen, die solche und ähnliche Probleme mitigieren sollen, derzeit nicht von Seitenbetreibern eingesetzt werden können, da sie auf die Funktionalität von Drittanbietern angewiesen sind. Dies zwingt den Seitenbetreiber dazu, zwischen Funktionalität und Sicherheit zu wählen

Studying JavaScript Security Through Static Analysis

Mit dem stetigen Wachstum des Internets wächst auch das Interesse von Angreifern. Ursprünglich sollte das Internet Menschen verbinden; gleichzeitig benutzen aber Angreifer diese Vernetzung, um Schadprogramme wirksam zu verbreiten. Insbesondere JavaScript ist zu einem beliebten Angriffsvektor geworden, da es Angreifer ermöglicht Bugs und weitere Sicherheitslücken auszunutzen, und somit die Sicherheit und Privatsphäre der Internetnutzern zu gefährden. In dieser Dissertation fokussieren wir uns auf die Erkennung solcher Bedrohungen, indem wir JavaScript Code statisch und effizient analysieren. Zunächst beschreiben wir unsere zwei Detektoren, welche Methoden des maschinellen Lernens mit statischen Features aus Syntax, Kontroll- und Datenflüssen kombinieren zur Erkennung bösartiger JavaScript Dateien. Wir evaluieren daraufhin die Verlässlichkeit solcher statischen Systeme, indem wir bösartige JavaScript Dokumente umschreiben, damit sie die syntaktische Struktur von bestehenden gutartigen Skripten reproduzieren. Zuletzt studieren wir die Sicherheit von Browser Extensions. Zu diesem Zweck modellieren wir Extensions mit einem Graph, welcher Kontroll-, Daten-, und Nachrichtenflüsse mit Pointer Analysen kombiniert, wodurch wir externe Flüsse aus und zu kritischen Extension-Funktionen erkennen können. Insgesamt wiesen wir 184 verwundbare Chrome Extensions nach, welche die Angreifer ausnutzen könnten, um beispielsweise beliebigen Code im Browser eines Opfers auszuführen.As the Internet keeps on growing, so does the interest of malicious actors. While the Internet has become widespread and popular to interconnect billions of people, this interconnectivity also simplifies the spread of malicious software. Specifically, JavaScript has become a popular attack vector, as it enables to stealthily exploit bugs and further vulnerabilities to compromise the security and privacy of Internet users. In this thesis, we approach these issues by proposing several systems to statically analyze real-world JavaScript code at scale. First, we focus on the detection of malicious JavaScript samples. To this end, we propose two learning-based pipelines, which leverage syntactic, control and data-flow based features to distinguish benign from malicious inputs. Subsequently, we evaluate the robustness of such static malicious JavaScript detectors in an adversarial setting. For this purpose, we introduce a generic camouflage attack, which consists in rewriting malicious samples to reproduce existing benign syntactic structures. Finally, we consider vulnerable browser extensions. In particular, we abstract an extension source code at a semantic level, including control, data, and message flows, and pointer analysis, to detect suspicious data flows from and toward an extension privileged context. Overall, we report on 184 Chrome extensions that attackers could exploit to, e.g., execute arbitrary code in a victim's browser