Long Term Evolution and Femtocells

Mini-ProjectSecurity and Cooperation in Wireless Networks | EPFLJanuary 19, 2010

By Igor Bilogrevic, LCA1Supervisor: Jean-Pierre Hubaux

Why Next Generation Networks ?

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Higher data-rate demands Smartphones, laptops with 3G modems,

multimedia apps

Origin of mobile network traffic*

Weak indoor coverage* Presentations by ABI Research, Picochip, Airvana, IP.access, Gartner, Telefonica Espana, 2nd Int’l. Conf. Home Access Points and Femtocells;http://www.avrenevents.com/dallasfemto2007/purchase_presentations.htm

Femtocells

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Home base stations for mobile networks Licensed spectrum Low-power, low-range At user’s premises Operated by cell. provider Cellular access through

fixed broadband connection (ADSL,…)

Why femtocells? Better throughput, coverage, lower prices for

users Unload wide area cellular networks, reduce op.

costs

Problem Statement

New mobile network architecture Long Term Evolution is All-IP (EPS) Untrusted connection: cell site operator User-installed but operator controlled

equipment

Challenges

Contributions19/01/2010Security and Privacy in Next Generation Mobile Networks 4

1. Context-aware, user-triggered temporary ID change

2. DDoS protection offer/demand model between ISPs and mobile operators

Outline

1. Related Work

2. Identity and Location Privacy Context-aware, user-triggered ID change

3. Distributed Denial of Service (DDoS) Protection

Location-aware DDoS defense for femtocell networks

4. Conclusion and Future Work

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1. Related Work

Privacy in cellular networks Subscriber de-anonymization using GSM

location traces [DeMulderDBP2008] Privacy-preserving 3-way authentication

protocol (PP3WAKA) [KoeinO2006] Mobile device – serving network – home network

Security in the core network Nobody talks about it Economics of DDoS attacks on femtocell

gateways [SeguraL2009] Criminal organizations queried for costs of

bandwidth attacks19/01/2010Security and Privacy in Next Generation Mobile Networks 6

2. Identity and Location Privacy Currently in UMTS/LTE

Each device is assigned a temporary identifier

Operator decides when to renew it (one each 100 cells)

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Pseudo A

Pseudo A

Pseudo B

Pseudo A

Pseudo C Pseudo

A

Pseudo D

7

2. Identity and Location Privacy Substantial research in

mobile/vehicular ad hoc networks Temporary identifiers (pseudonyms) Mix zones [FreudigerSH2009]

Idea for cellular networks

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Context-aware, device-triggered

temporary ID change

but

Challenges Standards Implementation

Intuition Use femtocell location

to enhance protection Only « insiders »

allowed to connect

Model Interaction ISPs – mobile op

ISPs offer protection, can collaborate Mobile operator chooses to be protected or not

Each entity wants to maximize individual benefits

3. DDoS Protection

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XX

XXXX

Femto GW

Attacker

« Game Theory … what else ? »

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Game Theory Stackelberg game Complete

information

Players Mob. Op leader, plays first ISPs followers, know

the leader’s strategy, one-shot game

Strategies Mob. Op. {Protected, Vulnerable} = {P, V} ISPs {Alone, Cooperate, Nothing} = {A, C,

N}

3. DDoS Protection

3. DDoS Protection

Payoffs

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“

,

,

,

,

Symbol Definition

catt Attack induced cost for Mob. Op.

ρ % of attack cost for which Mob. Op. wants to be protected

αj % of Internet traffic share of ISP j

j % of femtocell subscribers connected to Internet through ISP j

P # of cooperating ISPs

,

,

3. DDoS Protection

Results Mobile operator

ISP j

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3. DDoS Protection

Numerical evaluation 2 games

1 mobile operator, 2 ISPs

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= 0.5 = 0.9

Nash equilibrium is (Alone, Nothing)

Nash equilibrium is (Alone, Alone) ?

4. Conclusion Security and privacy are still an issue

LTE has shortcomings even before its debut All-IP is more efficient but more exposed to

attacks

Contributions Identified privacy and security challenges in LTE Suggested context-aware, user-triggered

temporary ID change inspired by MANET research

Modeled and numerically evaluated DDoS defense dynamics between ISPs and mobile network operators

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4. Future Work

Privacy Feasibility study of proposed idea Implementation on mobile devices (N900 ?)

How easy is it to get cell ID on mobile phone? P2P communication? How to trigger core network action?

DDoS Security Improve flaws of current model

Refine payoff functions, system parameters, effectiveness of ISPs if not exclusive provider

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References [DeMulderDBP2008] Y. De Mulder, G. Danezis, L. Batina, and

B. Preneel, “Identification via location-profiling in GSM networks,” in Proceedings of the 7th ACM workshop on Privacy in the electronic society. ACM New York, NY, USA, 2008, pp. 23–32.

[FreudigerSH2009] J. Freudiger, R. Shokri, and J.-P. Hubaux, “On the optimal placement of mix zones,” in The 9th Privacy Enhancing Technologies Symposium. Springer, 2009.

[KoeinO2006] G. Koien and V. Oleshchuk, “Location Privacy for Cellular Systems; Analysis and Solution,” Lecture Notes in Computer Science, vol. 3856, p. 40, 2006.

[SeguraL2009] V. Segura and J. Lahuerta, “Modeling the economic incentives of DDoS Attacks: femtocell case study,” The Eighth Workshop on the Economics of Information Security (WEIS 2009), 2009.

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Backup Slides

Network Architectures

3G: UMTS vs LTE

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Security and Privacy Challenges

New threats Attacks on femtocells Attacks on backhaul and core network (IPsec

tunnel)Security and Privacy in Next Generation Cellular Networks

Source: www.SafeNet-Inc.com

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Location and Identity Privacy UMTS and LTE identity

management Temporary identifiers (“pseudonyms”)

Security and Privacy in Next Generation Cellular Networks

LA 0LA 1

LA 2

LA 3

Pseudo A

Pseudo B

Pseudo C

Pseudo D

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