AppShield: Enabling Multi-entity Access Control Cross Platforms for Mobile App Management - PowerPoint Presentation

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Uploaded On 2018-11-21

AppShield: Enabling Multi-entity Access Control Cross Platforms for Mobile App Management - PPT Presentation

Zhengyang Qu 1 Guanyu Guo 2 Zhengyue Shao 2 Vaibhav Rastogi 3 Yan Chen 1 Hao Chen 4 Wangjun Hong 1 1 1 Northwestern University 2 Zhejiang University 3 University of Wisconsin Madison ID: 732143

file access data app access file app data high system application rewriting entity management dynamic university android sandbox policies

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Slide1

AppShield: Enabling Multi-entity Access Control Cross Platforms for Mobile App Management

Zhengyang Qu1, Guanyu Guo2, Zhengyue Shao2, Vaibhav Rastogi3, Yan Chen1, Hao Chen4, Wangjun Hong1

Northwestern University

Zhejiang University

University of Wisconsin, Madison

University of California, DavisSlide2

Android OS dominance

2Mobile OS Market Share, by

dazeinfo.com Slide3

Android malware/spyware

3Slide4

Birth of bring-your-own-

device4Slide5

Policies required in BYOD

5Slide6

Outline

IntroductionMotivationSystem OverviewEvaluationConclusion6Slide7

Common deployment of MAM

Application rewritingMocana, AirWatchWork on all devices, NOT on all applicationsSDKGood, Citrix, AirWatchWork on all applications, extra developer supportOS ModificationAndroid for work on Android 5.0 and aboveDependencies on OS versions or customizationLimitation of portability

7Slide8

Android segmentation

8Android OS distribution snapshot in March 2015 and September 2016Slide9

Desired system

GeneralityConvert any personal app to a business versionAbility of enforcing arbitrary access control policiesMulti-entity management, Role-based access control (RBAC), granularity…PortabilityNo modifications (dependencies) on OSCompletenessStealthy channels: reflection, native code, dynamic load Cross-platformExtend to other platforms, e.g. iOS9Slide10

Challenges

Lack of OS supportAndroid storage mechanism supports either data sharing or data isolation aloneDiversity of data access behaviorNative code, Java reflection, Dynamic loadingPerformance penaltyPopular resource virtualization-based solutions have the scalability issue10Slide11

Contributions

A proxy-based data access mechanism to enforce arbitrary access policies without OS dependencyAn application rewriting mechanism inject MAM features by hooking system calls to achieve complete mediationA prototype system with low latency and resource consumption 11Slide12

Outline

IntroductionMotivationSystem OverviewEvaluationConclusion12Slide13

Security model

13Slide14

Application rewriting

Application decompilationNativeCustomized system calls, e.g., ioctl(), open()Override Global Offset Table (GOT) BytecodeService: wrap the app, overwrite the GOT before app startsActivity: message popup, e.g., policy violationManifest fileDeclaring the Service and Activity injectedRequest the permission to access mirror content providerRepack and sign14Slide15

Proxy-based data access mechanism

15Slide16

Shield the privileged data

File-systemopen(), creat(), rename(), mkdir(), remove(): rewrite the file path to the internal storage of AppShieldstat(), lstat(): pass the file descriptor to business file to fstat()Content providerMirror content providerSystem call ioctl(): redirect data request16Slide17

Security policies

File isolationMulti-entity management & RBACFine-grained file access controlContent provider isolation17Slide18

Outline

IntroductionMotivationSystem OverviewEvaluationConclusion18Slide19

Effectiveness

Select 50 popular apps from Google Play35 file related apps, 15 contact provider related apps1 app crashes; 2 apps file path “/./sdcard”1 app cannot be rewritten; use “Intent” to directly start system contact manager app 19File isolationMulti-entity management & RBAC

File-level granularityContent provider isolation

Succeed

33/35

31/35

14/15Slide20

Reliability

Select 1000 apps by popularity from Google Play in categories: Business, Finance, Medical, ProductivityExecute by ADB MonkeyOriginal version also crash: 29 in 35Crash without code modification: 6 in 3520TotalSucceedRewriting failureCrash1000

953 (95.3%)12 (1.2%)35 (3.5%)Slide21

Impact of application rewriting

Micro: overall latency in 1000 data access:Macro: overall time for human to open/close a window rendering the privileged data21File systemContent providerOriginalAppShieldOriginal

AppShieldMicro (s)

0.180

0.382

7.303

9.014

Macro (s)

1.472

1.524

1.068

1.194

Average memory usage increment:

28840.3KB

Average code size increment:

33.7KBSlide22

Comparision

AirWatchMOCANAGOODCitrixAndroid LAppShield *MethodSDK & App rewritingApp rewriting

SDKSDKOS modification

App rewriting

Isolation

Sandbox

Encryption

DAC

Sandbox

Multi-entity

management

Yes

RBAC

Yes

Granularity

Static

Coarse dynamic

Static

Coarse dynamic

File-level dynamic

Sharing

Online

Local

Portability

High

Low

High

22Slide23

Conclusion

AppShield enforces arbitrary access control policies in the scenario of MAMApplication rewritingNo dependency on OS, high portabilitySystem call hooking, complete mediationLow overhead and impact on the original app 23Slide24

Thank you!http://list.cs.northwestern.edu/mobile/Questions?Slide25

System call h

ooking25