Android Re-delegation Finder (ARF)
Over the past decade, the security of the Android platform has undergone significant scrutiny by both academic and industrial researchers. This scrutiny has been largely directed towards third-party applications and a few critical system interfaces, leaving much of Android’s middleware unstudied. Building upon recent efforts to more rigorously analyze authorization logic in Android’s system services, we revisit the problem of permission re-delegation, but in the context of system service entry points. The Android Re-delegation Finder (ARF) analysis framework aids security analysts in the identification of permission re-delegation vulnerabilities within Android’s system services. ARF analyzes an interconnected graph of entry points in system services, deriving calling dependencies, annotating permission checks, and identifying potentially vulnerable deputies that improperly expose information or functionality to third-party applications.
For more information on ARF, including source code, please visit wspr.csc.ncsu.edu/arf.
Authorization Check Miner (ACMiner)
Billions of users rely on the security of the Android platform to protect phones, tablets, and many different types of consumer electronics. While Android’s permission model is well studied, the enforcement of the protection policy has received relatively little attention. Much of this enforcement is spread across system services, taking the form of hard-coded checks within their implementations. Authorization Check Miner (ACMiner) provides system developers and researchers with a framework for evaluating the correctness of Android’s access control enforcement through consistency analysis of authorization checks. ACMiner combines program and text analysis techniques to generate a rich set of authorization checks, mines the corresponding protection policy for each service entry point, and uses association rule mining at a service granularity to identify inconsistencies that may correspond to vulnerabilities.
For more information on ACMiner, including source code, please visit wspr.csc.ncsu.edu/acminer.
Android Security Modules (ASM)
Android, iOS, and Windows 8 are changing the application architecture of consumer operating systems. These new architectures required OS designers to rethink security and access control. While the new security architectures improve on traditional desktop and server OS designs, they lack sufficient protection semantics for different classes of OS customers (e.g., consumer, enterprise, and government). The Android OS in particular has seen over a dozen research proposals for security enhancements.
We seek to promote OS security extensibility in the Android OS. We propose the Android Security Modules (ASM) framework, which provides a programmable interface for defining new reference monitors for Android. We drive the ASM design by studying the authorization hook requirements of recent security enhancement proposals and identify that new OSes such as Android require new types of authorization hooks (e.g., replacing data). We describe the design and implementation of ASM and demonstrate its utility by developing reference monitors called ASM apps. Finally, ASM is not only beneficial for security researchers. If adopted by Google, we envision ASM enabling in-thefield security enhancement of Android devices without requiring root access, a significant limitation of existing bring-your-own-device solutions.
For more information on ASM, including source code, please visit androidsecuritymodules.org.
NativeWrap is an application wrapper for Android that configures native Android applications from URLs supplied by the user, which are then installed on the device. The whole process takes little or no effort from the user, as NativeWrap’s WebView wrapper comes preconfigured with security best practices (for e.g. SSL Pinning, Force HTTPS, etc.).
For more information on NativeWrap, including source code and link to Google Play Store version, please visit wspr.csc.ncsu.edu/nativewrap.
Modern OSes such as Android, iOS, and Windows 8 have changed the way consumers interact with computing devices. Tasks are often completed by stringing together a collection of purpose-specific user applications, as shown in the figure above (e.g., a barcode reader, a social networking app, a document viewer). As users direct this workflow between applications, it is difficult to predict the consequence of each step. Poor selection may result in accidental information disclosure when the target application unknowingly uses cloud services. Aquifer is a policy framework and system for preventing accidental information disclosure in modern operating systems. In Aquifer, application developers define secrecy restrictions that protect the entire user interface workflow defining the user task. In doing so, Aquifer provides protection beyond simple permission checks and allows applications to retain control of data even after it is shared.
For more information on Aquifer, including source code, please visit wspr.csc.ncsu.edu/aquifer.
Application markets such as Apple’s App Store and Google’s Play Store have played an important role in the popularity of smartphones and mobile devices. However, keeping malware out of application markets is an ongoing challenge. While recent work has developed various techniques to determine what applications do, no work has provided a technical approach to answer, what do users expect? In this paper, we present the ﬁrst step in addressing this challenge. Speciﬁcally, we focus on permissions for a given application and examine whether the application description provides any indication for why the application needs a permission. We present WHYPER, a framework using Natural Language Processing (NLP) techniques to identify sentences that describe the need for a given permission in an application description. WHYPER achieves an average precision of 82.8%, and an average recall of 81.5% for three permissions (address book, calendar, and record audio) that protect frequently used security and privacy sensitive resources. These results demonstrate great promise in using NLP techniques to bridge the semantic gap between user expectations and application functionality, further aiding the risk assessment of mobile applications.
For more information on WHYPER, including source code and data sets, please visit sites.google.com/site/whypermission/.