PolyScope: Multi-policy access control analysis to compute authorized attack operations in android systems

Yu Tsung Lee, William Enck, Haining Chen, Hayawardh Vijayakumar, Ninghui Li, Zhiyun Qian, Daimeng Wang, Giuseppe Petracca, Trent Jaeger

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Scopus citations

Abstract

Android's filesystem access control provides a foundation for system integrity. It combines mandatory (e.g., SEAndroid) and discretionary (e.g., Unix permissions) access control, protecting both the Android platform from Android/OEM services and Android/OEM services from third-party applications. However, OEMs often introduce vulnerabilities when they add market-differentiating features and fail to correctly reconfigure this complex combination of policies. In this paper, we propose the PolyScope tool to triage Android systems for vulnerabilities using their filesystem access control policies by: (1) identifying the resources that subjects are authorized to use that may be modified by their adversaries, both with and without policy manipulations, and (2) determining the attack operations on those resources that are actually available to adversaries to reveal the specific cases that need vulnerability testing. A key insight is that adversaries may exploit discretionary elements in Android access control to expand the permissions available to themselves and/or victims to launch attack operations, which we call permission expansion. We apply PolyScope to five Google and five OEM Android releases and find that permission expansion increases the privilege available to launch attacks, sometimes by more than 10x, but a significant fraction (about 15-20%) cannot be converted into attack operations due to other system configurations. Based on this analysis, we describe two previously unknown vulnerabilities and show how PolyScope helps OEMs triage the complex combination of access control policies down to attack operations worthy of testing.

Original languageEnglish (US)
Title of host publicationProceedings of the 30th USENIX Security Symposium
PublisherUSENIX Association
Pages2579-2596
Number of pages18
ISBN (Electronic)9781939133243
StatePublished - 2021
Event30th USENIX Security Symposium, USENIX Security 2021 - Virtual, Online
Duration: Aug 11 2021Aug 13 2021

Publication series

NameProceedings of the 30th USENIX Security Symposium

Conference

Conference30th USENIX Security Symposium, USENIX Security 2021
CityVirtual, Online
Period8/11/218/13/21

All Science Journal Classification (ASJC) codes

  • Computer Networks and Communications
  • Information Systems
  • Safety, Risk, Reliability and Quality

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