addroid!! privilege!separaon!for!applicaons! …pearce/talks/addroid_asiaccs_2012.pdf ·...
TRANSCRIPT
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AdDroid Privilege Separa,on for Applica,ons
and Adver,sers in Android Paul Pearce1, Adrienne Porter Felt1, Gabriel Nunez2,
David Wagner1 1 University of California, Berkeley
2 Sandia Na,onal Laboratory May 4, 2012
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SCARY CAMPFIRE STORY
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Android Market
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Android Market Android Market Search
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Market Search Results
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Market Search Results App Install Dialog
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Market Search Results App Install Dialog App Permissions Dialog
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Market Search Results App Install Dialog App Permissions Dialog
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Market Search Results
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Market Search Results
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Market Search Results App Install Dialog
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Market Search Results App Install Dialog App Permissions Dialog
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Market Search Results App Install Dialog App Permissions Dialog
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Market Search Results
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Market Search Results
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Market Search Results
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Market Search Results
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Market Search Results App Install Dialog
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Market Search Results App Install Dialog App Permissions Dialog
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What’s happening here?
Adver;sements • App developers use ads for revenue
• Ad networks overprivilege apps – Ads are part of apps – Ads require permissions that apps may not
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Key Points
• Adver,sing overprivileges 49% of ad-‐supported applica,ons (28% of all applica,ons) on Android
• We present AdDroid, a privilege separated adver,sing framework to solve this problem
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ANDROID AND ADVERTISING BACKGROUND
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Ads in Applica,ons Market Search Results
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Ads in Applica,ons Market Search Results
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Ads in Applica,ons Market Search Results Brightest Flashlight App
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Ads in Applica,ons Market Search Results Brightest Flashlight App
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Android Browser
Ads in Applica,ons Market Search Results Brightest Flashlight App
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Android Permissions
• A permission gives an app the ability to perform a privacy-‐ or security-‐ relevant ac,on – E.g. INTERNET controls network access, ACCESS_FINE_LOCATION control GPS access
• Permissions are requested by apps at install-‐;me. – Once granted, users are not asked again
• Permissions are enforced by the Android Pla[orm
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Adver,sing Libraries
• Adver,sing networks distribute adver,sing libraries for app developers to use
• Developers integrate these libraries into their applica,ons – Permissions are enforced at the granularity of applica,ons – Adver;sing libraries and host applica;ons share permissions
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Current Android System Design
API Permission Checks
Application
Host Applicaton
http
Android Platform
AdvertisingLibrary
Phone Web
API CallsAdvertisingNetwork
http
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WHAT CAN GO WRONG
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What Can Go Wrong • Users can’t determine if an app uses ads • Users can’t differen,ate permissions used by an app from those used by ads – What if I trust one principal more than the other?
• Ad libraries can introduce vulnerabili,es to apps – Some ad libraries download code over HTTP
• Ad libraries may not be trustworthy – Some ad libraries opportunis,cally use host app permissions
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MEASURING THE PROBLEM
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Methodology • Analyze a set of 964 applica,ons collected from the Android Market – 764 most popular free – 100 most popular paid – 100 most recent free
• Disassemble each applica,on into the host applica,on and the adver,sing library components
• Use sta,c analysis to determine which component used each permission
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Measurement Results: Ad Usage
Percent of apps using at least 1 ad library
Total apps
Top Free Apps 50.4% 764 Top Paid Apps 16.0% 100
Recent Free Apps 72.0% 100
• 49% of applica,ons in our dataset contain 1 or more adver,sing library
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Measurement Results: Overprivilege
Permission to access Percent of apps
reques;ng permission only for ads
Total apps reques;ng
The Internet (INTERNET) 16.2% 809
Loca,on (LOCATION) 33.5% 361
IMEI iden,fier(READ_PHONE_STATE) 12.8% 312
Network informa,on(ACCESS_NETWORK_STATE) 9.1% 395
• Adver,sing libraries overprivilege: – 46% of applica,ons with adver,sements – 28% of all apps
• Breakdown of applica,ons that use loca,on only for adver,sing – 56% of ad-‐supported applica,ons – 34% of all applica,ons
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ADDROID: A SOLUTION TO OVERPRIVILEGING
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Design Overview • Key idea: Separate privacy-‐sensi;ve ad func;onality from applica;ons
• AdDroid is an extension to Android that provides special support for ads
• Applica,ons that want adver,sements now request new ADS permissions, not INTERNET or LOCATION – Gives apps the ability to have ads without INTERNET or LOCATION
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AdDroid Design
API Permission Checks
Application
Host Applicaton
Android Platform
Phone Web
API CallsAdvertisingNetwork
httphttp
AdvertisingLibrary
Android Platform
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AdDroid Design
API Permission Checks
Application
Host Applicaton
Android Platform
Phone Web
API CallsAdvertisingNetwork
AdvertisingLibrary
Android Platform
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AdDroid Design
API Permission Checks
Application
Host Applicaton
Android Platform
Phone Web
API CallsAdvertisingNetwork
Android Platform
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AdDroid Design
API Permission Checks
Application
Host Applicaton
Android Platform
Phone Web
API CallsAdvertisingNetwork
AdvertisingService
Android Platform
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AdDroid Design
API Permission Checks
Application
Host Applicaton
Android Platform
Phone Web
API CallsAdvertisingNetwork
https
https
AdvertisingService
Android Platform
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New Permissions Adver,sing Loca,on based Adver,sing
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What Can Go Wrong Right • Users can determine if an app uses ads • Users can differen,ate permissions used by an app from those used by ads – Apps don’t request addi,onal permissions for ads, besides the ads permissions themselves
• Ad libraries can’t introduce vulnerabili,es or abuse app permissions – Ad libraries replaced with standard Android library code
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Compa,bility and Prac,cality • Compa,ble with exis,ng applica,ons and libraries – If you don’t want to use the AdDroid API, you just don’t get the benefits
• Easy for app developers to adopt – API based on exis,ng adver,sing libraries
• Incremental system change – Adver,sing Service model similar to exis,ng services
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CONCLUSION
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Conclusion • Adver,sing related overprivilege impacts much of the Android ecosystem – 49% of all ad-‐supported apps (28% of all apps) are overprivileged by adver,sing libraries
– This poses a variety of problems for users and developers
• AdDroid solves these problems by isola,ng privileged privacy-‐sensi,ve ad func,onality from applica,ons
• Ques;ons?