Abstract Mobile phones have evolved into indispensable devices that run many exciting applications that users can download from phone vendor's application stores. However, as it is not practical to fully vet all application code, users may download malware‐infected applications, which may steal or modify security‐critical data. In this paper, we propose a security architecture for phone systems that protects trusted applications from such downloaded code. Our architecture uses reference monitors in the operating system and user‐space services to enforce mandatory access control policies that express an approximation of Clark—Wilson integrity. In addition, we show how to justify the integrity of mobile phone applications by using the Policy Reduced Integrity Measurement Architecture (PRIMA), which enables a remote party to verify the integrity of applications running on a phone. We have implemented a prototype on the Openmoko Linux Platform, using an SELinux kernel with a PRIMA module and user‐space services that leverage the SELinux user‐level policy server. We find that the performance of enforcement and integrity measurement is satisfactory, and the SELinux reference policy can be reduced in size by 90% (although more reduction should be possible), enabling practical system integrity with a desirable usability model. Copyright © 2010 John Wiley & Sons, Ltd.

Abstract Mobile phones have evolved from simple voice terminals into highly‐capable, general‐purpose computing platforms. While people are becoming increasingly more dependent on such devices to perform sensitive operations, protect secret data, and be available for emergency use, it is clear that phone operating systems are not ready to become mission‐critical systems. Through a pair of vulnerabilities and a simulated attack on a cellular network, we demonstrate that there are a myriad of unmanaged mechanisms on mobile phones, and that control of these mechanisms is vital to achieving reliable use. Through such vectors, mobile phones introduce a variety of new threats to their own applications and the telecommunications infrastructure itself. In this paper, we examine the requirements for providing effective mediation and access control for mobile phones. We then discuss the convergence of cellular networks with the Internet and its impact on effective resource management and quality of service. Based on these results, we argue for user devices that enable predictable behavior in a network—where their trusted computing bases can protect key applications and create predictable network impact. Copyright © 2010 John Wiley & Sons, Ltd.

The vast expansion of interconnectivity with the Internet and the rapid evolution of highly-capable but largely insecure mobile devices threatens cellular networks. In this paper, we characterize the impact of the large scale compromise and coordination of mobile phones in attacks against the core of these networks. Through a combination of measurement, simulation and analysis, we demonstrate the ability of a botnet composed of as few as 11,750 compromised mobile phones to degrade service to area-code sized regions by 93%. As such attacks are accomplished through the execution of network service requests and not a constant stream of phone calls, users are unlikely to be aware of their occurrence. We then investigate a number of significant network bottlenecks, their impact on the density of compromised nodes per base station and how they can be avoided. We conclude by discussing a number of countermeasures that may help to partially mitigate the threats posed by such attacks.

In this paper, we present a mandatory access control system that uses input from multiple stakeholders to compose policies based on runtime information. In the emerging open cell phone system environment, many devices run software whose access permissions depends on multiple stakeholders, such as the device owner, the service provider, the application owner, etc., rather than a single system administrator. However, current access control administration remains as either discretionary, allowing the running and perhaps compromised process to administer permissions, or mandatory, requiring a system administrator to know all permissions for all possible legal runs. A key problem is that users may download arbitrary programs to their devices, requiring that the system contain such programs while allowing some reasonable functionality. However, such programs may need access to permissions that in combination with other conflicting permissions may lead to an attack, such as allowing voice-over-IP calls. In our approach, we use a "soft" sand-boxing mechanism to first contain such processes, request the stakeholder to authorize operations outside the sandbox that are not prohibited by policy, and maintain a runtime execution role for the process to identify its access state to the stakeholders. We define a proxy policy server that caches and combines stakeholder policies to make such access decisions. Our framework was implemented by modifying the SELinux module and using a remote proxy policy server, although a local proxy policy server is also possible. We incur a 0.288 ts performance overhead only when stakeholders need to be consulted, and new permissions are cached.