An Historical Analysis of the SEAndroid Policy Evolution

Android adopted SELinux's mandatory access control (MAC) mechanisms in 2013. Since then, billions of Android devices have benefited from mandatory access control security policies. These policies are expressed in a variety of rules, maintained by Google and extended by Android OEMs. Over the years, the rules have grown to be quite complex, making it challenging to properly understand or configure these policies. In this paper, we perform a measurement study on the SEAndroid repository to understand the evolution of these policies. We propose a new metric to measure the complexity of the policy by expanding policy rules, with their abstraction features such as macros and groups, into primitive "boxes", which we then use to show that the complexity of the SEAndroid policies has been growing exponentially over time. By analyzing the Git commits, snapshot by snapshot, we are also able to analyze the "age" of policy rules, the trend of changes, and the contributor composition. We also look at hallmark events in Android's history, such as the "Stagefright" vulnerability in Android's media facilities, pointing out how these events led to changes in the MAC policies. The growing complexity of Android's mandatory policies suggests that we will eventually hit the limits of our ability to understand these policies, requiring new tools and techniques.Comment: 16 pages, 11 figures, published in ACSAC '1

ENABLING ATTRIBUTE BASED ACCESS CONTROL WITHIN THE INTERNET OF THINGS (IOT)

With the wide-scale development of the Internet of Things (IoT) and the usage of low-powered devices (sensors) together with smart devices, numerous people are using IoT systems in their homes and businesses to have more control over their technology. Unfortunately, some users of IoT systems that are controlled by a mobile application do not have a high level of data protection to respond in case the device is lost, stolen, or used by one of the owner’s friends or family members. The problem studied in this research is how to apply one of access control methods an IoT system whether they are stored locally on a sensor or on a cloud. To solve the problem, an attribute-based access control (ABAC) mechanism is applied to give the system the ability to apply policies to detect any unauthorized entry by evaluating some of the users’ attributes: the accessed time, the device media access control address (MAC address), the username, and password. Finally, a prototype was built to test the proposed solution in two ways; one is locally on a low-powered device, the second using cloud platform for the data storage. To evaluate both the prototype implementation, this research had an evaluation plan to mimic the real-world interactions by obtaining the response times when different numbers of requests sent from diverse numbers of users in different delays. The evaluation results showed that the first implementation was noticeably faster than the second implementation

An extension to the Android access control framework

Several nice hardware functionalities located at the low level of operating system on mobile phones could be utilized in a better way if they are available to application developers. With their help, developers are able to bring overall user experience to a new level in terms of developing novel applications. For instance, one of those hardware functionalities, SIM-card authentication is able to offer stronger and more convenient way of authentication when compared to the traditional approach. Replacing the username-password combination with the SIM-card authentication, users are freed from memorizing passwords. However, since normally those kinds of functionalities are locked up at the low level, they are only accessible by a few users who have been given privileged access rights. To let the normal applications be benefiting as well, they need to be made accessible at the application level. On the one hand, as we see the benefit it will bring to us, there is a clear intention to open it up, however, on the other hand, there is also a limitation resulting from their security-critical nature that needs to be placed when accessing which is restricting the access to trusted third parties. Our investigation is based on the Android platform. The problem that we have discovered is the existing security mechanism in Android is not able to satisfy every regards of requirements we mentioned above when exposing SIM-card authentication functionality. Hence, our requirement on enhancing the access control model of Android comes naturally. In order to better suit the needs, we proposed a solution White lists & Domains (WITDOM) to improve its current situation in the thesis. The proposed solution is an extension to the existing access control model in Android that allows alternative ways to specify access controls therefore complementing the existing Android security mechanisms. We have both designed and implemented the solution and the result shows that with the service that we provided, critical functionalities, such as APIs for the low-level hardware functionality can retain the same level of protection however in the meanwhile, with more flexible protection mechanism