Can Ferris Bueller Still Have His Day Off? Protecting Privacy in the

Wireless EraAuthors: Ben Greenstein, Ramakrishna Gummadi,

Jeffrey Pang,Mike Y. Chen, Tadayoshi Kohno,Srinivasan Seshan,

David WetherallPresenter: Yinzhi Cao

Introduction

• The advent of mobile devices and ubiquitous computing devices has really pushed security and privacy in this environment to the forefront and is fast developing as an important area of research.

• A device can be indentified and tracked over time through its persistent link-layer address, list of known networks(SSIDs), and other protocol and physical layer characteristics.

802.11 Case Study (1)

802.11 Case Study (1) CONT’D

802.11 Case Study (1) CONT’D

• ResultPeople may know that Ferris went to Park on

Tuesday while he says he is sick and should be at home.

802.11 Case Study(2)

802.11 Case Study(3)

802.11 Case Study(3)

• Sequence Number Field (the rate of package transmissions)

• Traffic Indication Map in beacon frames for clients using power-save functionality(count of power-save user number)

Research Challenge

• Naming• Discovering resources and binding• Limiting information leakage

Naming

• Unique MAC address Leakage• Solution:– Periodically Changing MAC addresses

(Pseudonym)– Hiding Persistent ID

• Problem– Pseudonyms can be linked together– Link 802.11 with bluetooth– Prevent Normal Users

Discovering resources and binding

• Designing Goal– Only clients who are authorized to use a private

service should be capable of learning of its presence.

– At most the client and the service involved should know when a binding is established or broken between them; optionally, the identity of the client may be hidden from the service as well.

Limiting information leakage

• We can’t encrypt all the frames.– some link header fields are designed to be

broadcast to all users. For example, the duration field.

– if a client were to encrypt the remaining fields so that only the AP could decrypt them, then the AP would suffer additional computation load, and would thus be more susceptible to denial-of-service attacks

Devices That Tell On You: Privacy Trends in Consumer Ubiquitous

ComputingAuthors: T. Scott Saponas, Jonathan

Lester, Carl Hartung, Sameer Agarwal,Tadayoshi Kohno

Presenter: Yinzhi Cao

The Sling Media Slingbox Pro

• Usage– allows users to remotely view (sling) the contents

of their TV over the Internet

• Vulnerability– Based on throughput, we can deduce which TV

program users are watching

The Sling Media Slingbox Pro

The Sling Media Slingbox Pro Cont’d

• Method

The Sling Media Slingbox Pro Cont’d

• Result

The Nike+iPod Sport Kit: Devices that Reveal Your Presence

• Usage– The Nike+iPod Sport Kit allows runners and

walkers to hear real time workout progress reports on their iPod Nanos.

The Nike+iPod Sport Kit: Devices that Reveal Your Presence Cont’d

• Vulnerability

Zunes: Challenges with Managing Ad Hoc Mobile Social Interactions

• Usage– portable media devices to include wireless

capability for the purpose of sharing media– Block Mechanism

Zunes: Challenges with Managing Ad Hoc Mobile Social Interactions

• Circumventing the Zune Blocking Mechanism– Disappearing attack Zune– Fake MAC addresses– Post-blocking privacy

Thank you