security analysis of android for work - research project #1delaat/rp/2015... · binder ipc isolate...

Security Analysis of Android for WorkResearch Project #1

Tom Curran & Ruben de Vries

RP1 project presentation, 2016

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What is Android for Work

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Why is it interesting?

Data separation achieved using separate user profilesProfiles run concurrently

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Research Question

Is it possible to read data from the work profile using a process started bythe personal profile?

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Research Question; narrowed down

Is it possible to read data from a managed profile from the userprofile using the binder?

How does Android for Work handle encryption of data?

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Findings

Data can be read via the Binder

Data is encrypted when device is switched off, but not once it isrunning.

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Encryption; Demo

[...] Once a device is encrypted, all user-created data is automaticallyencrypted before committing it to disk and all reads automatically decryptdata before returning it to the calling process.

- Android for Work Security White Paper

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Root?

Root exploits uncovered in the past

Towel Root, affecting up to KitKat 4.4.2 (2014)Stagefright 2.0, affects up to Lollipop 5.1 (2015)

Rooting Marshmallow 6.0+ Harder but possible

SELinuxExploits in Linux kernel e.g. CVE-2016-0728 (2016)Fuzzing Android System Services by Binder, Blackhat 2015

Once you have root, lie about having it

All Your Root Checks Are Belong to Us, Blackhat 2015

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Android Version Distribution

Figure: Collected over 7-day period ending on 4th January 2016, Google.

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Application Sandboxing

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Binder IPC

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Binder IPC

Isolate kernel from user apps

All communication between processes passes via the Binder

Any data type can be sent

Two components: kernel driver and library loaded in applications

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Attacking the Binder?

1 Inject code into target service

2 Hook the function writing data to the driver

3 Listen on target service

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Attacking Android for Work?

Services shared between users

KeyboardPhone calls...

Flexible

Nothing displayed on UI

Subvert file-based encryption from Enterprise apps (e.g. SophosMobile Encryption)?

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Is it really practical?

Number of obstacles to first overcome

Gaining root accessBypassing SELinuxAvoiding root detection

Will never achieve 100% security

Layered securityEncrypt the trafficMinimize data travelling acrosss Binder

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Conclusion

Data is not encrypted while device is running

Bypassing root detection from MDMs is possible

Data flowing through the Binder can be read by other rooted users

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Questions?

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