Aster: Fixing the Android TEE Ecosystem with Arm CCA
OPEN ACCESS
Loading...
Author / Producer
Date
2024-07-23
Publication Type
Working Paper
ETH Bibliography
yes
Citations
Altmetric
OPEN ACCESS
Data
Rights / License
Abstract
The Android ecosystem relies on either TrustZone (e.g., OP-TEE, QTEE, Trusty) or trusted hypervisors (pKVM, Gunyah) to isolate security-sensitive services from malicious apps and Android bugs. TrustZone allows any secure world code to access the normal world that runs Android. Similarly, a trusted hypervisor has full access to Android running in one VM and security services in other VMs. In this paper, we motivate the need for mutual isolation, wherein Android, hypervisors, and the secure world are isolated from each other. Then, we propose a sandboxed service abstraction, such that a sandboxed execution cannot access any other sandbox, Android, hypervisor, or secure world memory. We present Aster which achieves these goals while ensuring that sandboxed execution can still communicate with Android to get inputs and provide outputs securely. Our main insight is to leverage the hardware isolation offered by Arm Confidential Computing Architecture (CCA). However, since CCA does not satisfy our sandboxing and mutual isolation requirements, Aster repurposes its hardware enforcement to meet its goals while addressing challenges such as secure interfaces, virtio, and protection against interrupts. We implement Aster to demonstrate its feasibility and assess its compatibility. We take three case studies, including one currently deployed on Android phones and insufficiently secured using a trusted hypervisor, to demonstrate that they can be protected by Aster.
Permanent link
Publication status
published
Editor
Book title
Journal / series
Volume
Pages / Article No.
2407.16694
Publisher
Cornell University
Event
Edition / version
v1
Methods
Software
Geographic location
Date collected
Date created
Subject
Cryptography and Security (cs.CR); FOS: Computer and information sciences
Organisational unit
03755 - Capkun, Srdan / Capkun, Srdan
09730 - Shinde, Shweta Shivaji / Shinde, Shweta Shivaji