Upload
lacey-isgrigg
View
218
Download
5
Tags:
Embed Size (px)
Citation preview
1 © NOKIA FILENAMs.PPT/ DATE / NN
Mobile Technology Overview
Ed Gibbs
Technologist
ISSA - September 20, 2001
Sacramento, California
2 © NOKIA FILENAMs.PPT/ DATE / NN
Ed Gibbs Biography
• Prior: Digital Equipment Corporation, Lockheed-Martin, Dow Jones & Company, and a few start-ups that don’t exist anymore!
• Focus on Firewalls, VPN, internetworking, 802.11, Mobile Data including WAP, and carrier infrastructure
• Recently completed chapter for Eoghan Casey’s new book“Handbook of Computer Crime” to be published in
October/Nov.• Collecting digital evidence within a cellular and 802.11
network
• Contact Information:• Nokia, 313 Fairchild Drive, Mountain View, CA 94043• Mobile: +1 650-868-9091• E-mail: [email protected]
3 © NOKIA FILENAMs.PPT/ DATE / NN
Introduction
• Why is understanding Cellular networking important?• As voice and data merge over cellular networks, you
may be tasked securing both• Wireless data handsets are inescapable
• Carrier infrastructures are very complex – to what degree should one become acquainted?
• Just the basics – that’s what we’ll cover here today• As security experts, there’s significant value in
obtaining this knowledge to prepare you for the future
• Carriers have enjoyed closed networks, opening them up to the Internet is a major challenge
4 © NOKIA FILENAMs.PPT/ DATE / NN
Types of Cellular Networks
5 © NOKIA FILENAMs.PPT/ DATE / NN
Analog Mobile Phone Service
• What is AMPS:• Commercially available in 1970 by Bell Telephone
Laboratories• Geographic areas are subdivided into smaller areas
which are commonly known as “cells”• Each cell has it’s own antenna that is set to operate
at distinct transmission frequencies
• Communications occur at a set frequency in each direction
• AMPS is still widely used today
7-cell pattern, each with different frequencies to avoid interference
824Mhz to 894Mhz with 30Khz of bandwidth separation per assigned channel for Transmit/Receive
6 © NOKIA FILENAMs.PPT/ DATE / NN
Digital Advanced Mobile Phone Service
• D-AMPS is far more complex than AMPS and supports two modes of operations
• Voice traffic is digital• AMPS used for channel setup and signaling• IS-54 – Uses Time-Division Multiple Access (TDMA) to
divide the radio channels used by AMPS• IS-136 (D-AMPS 1900) supports dual-mode, dual-
band:– Dual-Mode: Analog or Digital– 800Mhz cellular frequency used by AMPS– 1900Mhz frequency spectrum – Personal
Communications Service (PCS)– Allows for pages and short message services (SMS) of
up to 239 characters
7 © NOKIA FILENAMs.PPT/ DATE / NN
Time Division Multiple Access
• TDMA separates users by assigned time slots, which minimizes interference from other simultaneous transmissions
• Disadvantage: When changing cells (handoff), the assigned time-slot in the new cell may already be occupied however this is a capacity problem
• Transmission (uplink/downlink or send/receive) is allocated two slots:
• One used at a defined frequency for uplink• Second used at a particular frequency for downlink
• Extends battery life-time of handset by only transmitting a portion of time instead of a continuous transmission
• AT&T, Cingular (Eastern/Central US) uses TDMA• Cingular formally PacificBell uses a technology called
GSM which is not compatible with TDMA
8 © NOKIA FILENAMs.PPT/ DATE / NN
Code Division Multiple Access
• CDMA (IS-95) offers 6-10x the capacity of TDMA and uses codes to separate users as opposed to TDMA, which uses assigned time slots
• Uses broadband spread-spectrum developed in the 1940s for military purposes and uses a direct sequence technique, with the spreading sequence based on a pseudorandom binary sequence
• Also uses the 800Mhz and 1900Mhz frequency bands.• When using 800Mhz AMPS mode, more AMPS channels
needed to obtain frequency for CDMA (operator must clear 1.23Mhz/30khz or 41 channels) to accommodate
• When in 1900Mhz mode, CDMA uses PCS
• Directly supports IP packet data protocols
• Sprint, SBC uses CDMA
9 © NOKIA FILENAMs.PPT/ DATE / NN
Global System for Mobile Communications
• GSM developed in Europe in 1980s and became an international standard 13 years later
• There are two standards:• European: 900Mhz (International Standard)• North American – 800Mhz (900Mhz used by Government)
and 1900Mhz GSM PCS• North American GSM and European GSM are not compatible due to their
frequency• Tri-mode phones are available that operate at 800Mhz, 900Mhz, and
1900Mhz
• Uses TDMA framework but not compatible• Subdivides each radio channel into eight time slots; D-
AMPS subdivides into six time slots• Over 250 GSM Networks are presently operating in 110
countries• Data rates: 9.6Kbps to 14.4Kbps• Carriers: Pacific Bell (now Cingular), VoiceStream, and now
AT&T Wireless
10 © NOKIA FILENAMs.PPT/ DATE / NN
GSM
• GSM uses the Subscriber Information Module (SIM card) which comes in two forms – credit card sized format and thumb tip size
• Embedded in the card is a microprocesor, ROM and RAM
• Also contains data such as:• The subscriber’s phone number which is referred to
as the MSISDN (Mobile Subscriber ISDN Number)• The IMSI (International Mobile Subscriber Identity).
The IMSI is globally unique to a particular subscriber• The subscriber’s PIN which is used to prevent
unauthorized use of the mobile device• Authentication Keys
11 © NOKIA FILENAMs.PPT/ DATE / NN
Carrier Infrastructure
12 © NOKIA FILENAMs.PPT/ DATE / NN
Simple Architecture
Radio Access Network
Base Station
Core Network
SwitchSubscriberInformation
BillingRecords
Network Operationsand Maintenance
To otherNetworks
Mobile Device
Radio Link
13 © NOKIA FILENAMs.PPT/ DATE / NN
Detailed Architecture
BSC
BTS
BTS
BTS
Mobile Phone
BSC
BTS
BTS
BTS
MSC
VLR HLR
ChargingGateway
SMSc
LIG
To other networks(e.g. PSTN)
OMC
Connected to all elements inthe core network
Connectedto all BSCs
Radio Access Network
Core Network
14 © NOKIA FILENAMs.PPT/ DATE / NN
Network Operation Parameters
• The adjunct processor handling operational issues may handle records that drill down deep into the network operation details. These records can cover such items as:
• A subscriber’s phone call attempt
• Whether the attempt was successful
• Whether the call was ended normally or was dropped
• Date and time of the call
• Signal strength of the subscriber’s mobile device as seen by the BTS
• In what cell site was the call set up
• In what cell site sector was the call set up
• Handover information
• What channel was used
• What frequency/time slot/PN number was used
15 © NOKIA FILENAMs.PPT/ DATE / NN
Surveillance & Tracking
16 © NOKIA FILENAMs.PPT/ DATE / NN
Methods of Tracking• AOA: By knowing the direction from which a wireless signal is
received (via the use of special antennas at the cell site), Angle of Arrival techniques calculate the location of a mobile device.
• This technology is deployed at the cell sites of the network operator.
• TDOA: Time Difference of Arrival technology uses the difference in time that it takes for a wireless signal to arrive at multiple cell sites to calculate the location of the mobile device.
• This technology is deployed at the cell sites of the network operator.
• E-OTD: Enhanced Observed Time Difference involves a mobile device receiving the signals from at least three base stations, while a special receiver in the network (at a known position) also receives these signals.
• The mobile device location is calculated by comparing the time differences of arrival of the signals from the base stations at both the mobile device and the special receiver.
• This technology is deployed at cell sites and in the mobile device itself.
17 © NOKIA FILENAMs.PPT/ DATE / NN
Methods of Tracking
• Triangulation is a process by which the location of a radio transmitter can be determined by measuring either the radial distance, or the direction of the received signal from two or three different points
• Time delay response can be used in conjunction with triangulation to determine how far away the signal is between multiple points
• When a cell phone is turned on – it’s communicating! • Call or standby mode
• Tracking is often difficult if not impossible in some situations
• Signal reflection, distortion, weak signal, etc.
18 © NOKIA FILENAMs.PPT/ DATE / NN
Triangulation & Timed Response
Base •X
Base•Z
Base•Y
•Cell Phone
Measured Response
Time + Direction
•
19 © NOKIA FILENAMs.PPT/ DATE / NN
Lawful Interception
MSC/VLR
EIRHLR
Gi
Gs
Gf
Gr
GSM & UMTS
SGSN
GGSN
Gn
3GGPRS backbone
PDN
Gp
20 © NOKIA FILENAMs.PPT/ DATE / NN
Functional Roles
Law Enforcement
Authority (LEA)
AuthorisationAuthority (AA)
Network Operator
EquipmentManufacturer
User
Host/Terminal
Target User1 2
2
4
4
3
4
5
21 © NOKIA FILENAMs.PPT/ DATE / NN
Authorizing interceptions
Authorizing Agency (AA)
• Authorizes session using the web interface at the LIC
22 © NOKIA FILENAMs.PPT/ DATE / NN
Enabling interceptions
Law Enforcement Agency (LEA)
• Starts interception at the LIC
23 © NOKIA FILENAMs.PPT/ DATE / NN
E911 Update
• August 2000: FCC adopted an Order to implement the Wireless Communications and Public Safety Act of 1999 (911 Act), enacted on October 26,1999.
• Implemented in two phases:• First Phase – Reveals cell phone number and base-
station caller is using• Second Phase – Pinpoints location accurate within 50-100
meters
• October 1, 2001 Deadline will “not be met”
• All major carriers will file an extension with the FCC• Location based service and tracking software not in
place
• Only %10 of law enforcement is equipped to handle E911
• Official Web-site• http://www.fcc.gov/e911/
24 © NOKIA FILENAMs.PPT/ DATE / NN
Steps to 3rd Generation within the US
Basic GSM data at 9.6 kbit/s & Smart messaging
1997Landline-like circuit services (HSCSD) & Interactive messaging (USSD)2000
Internet-like IP packet services for mass market (GPRS) 144Kbps2001-2002
Enhanced speed and capacity (EDGE)2002
EvolutionEvolution
New multimedia servicesMass market cost of service (WCDMA)2Mbps
2003-2005
Introduction of 3rd generation radio
Development of R
adio Technology
Development of R
adio Technology
25 © NOKIA FILENAMs.PPT/ DATE / NN
GPRS Architecture
VPN VPN
Firewall
Firewall
26 © NOKIA FILENAMs.PPT/ DATE / NN
WAP
27 © NOKIA FILENAMs.PPT/ DATE / NN
Wireless Application Protocol (WAP)
• De-facto world standard for wireless information and telephony services on digital mobile phones and other wireless terminals
• "Internet in Every Pocket"• Objectives:
General environment for wireless applications Internet or Intranet-like services and content to mobile terminals Network, bearer and manufacturer independent
• WAP Forum Started 1997 by Nokia, Ericsson, Motorola and Unwired Planet Now close to 500 member companies
• WAP 1.1 (June ‘99) • The first release for commercial products
• WAP 1.2 (December ’99)
28 © NOKIA FILENAMs.PPT/ DATE / NN
Web Server
Content
CGIScripts
etc.
WM
L D
ecks
wit
h W
ML
-Scr
ipt
WAP Gateway
WML Encoder
WMLScriptCompiler
Protocol Adapters
Client
WML
WML-Script
WTAI
Etc.
HTTPWSP/WTP
WAP System Architecture
29 © NOKIA FILENAMs.PPT/ DATE / NN
Common WAP Deployment Scenarios
Mobile
Customer
Dial-inServer
WAPServer/Gateway
Content & ApplicationsServer (s)
Total Corporate Solution
Closed WAP Portal e.g. Operator / ISP
Business ModelTechnical Architecture
Typical WAP Enabled 'Web Destination Site'
Open WAP Portal + Content providers and Merchants
Key
Enterpr. hosted
xSP hosted
30 © NOKIA FILENAMs.PPT/ DATE / NN
Wireless Transport Layer Security
• WTLS provides encryption from the mobile handset to the WAP Gateway
• WTLS to SSL conversion on WAP gateway must decrypt WTLS and re-encrypt to SSL
• Vulnerability: Clear-text
• Four classes:• Class 0: No Security• Class 1: Server Authentication (dh_anon)
• Available today• Class 2: Signed Server Certificate
• Available today• Class 3: Signed Client Servificate
• Coming Soon
31 © NOKIA FILENAMs.PPT/ DATE / NN
WTLS
32 © NOKIA FILENAMs.PPT/ DATE / NN
Wireless Identity Module (WIM)
Terminal HW
(terminal SW)
Additional chip,
"Dual chip"
Integrated reader I.e."dual slot"
External reader
• Wireless PKI Capability
• WIM has five implementation possibilities
WIM inside SIM = SWIM
33 © NOKIA FILENAMs.PPT/ DATE / NN
WAP Modes
• The four modes for WAP communications are:
Mode UDP Port WTLS Security• Connectionless 9200 No• Connection 9201 No• Connectionless 9202 Yes• Connection 9203 Yes
34 © NOKIA FILENAMs.PPT/ DATE / NN
Terminal
WAP Gateway Origin Server
Wireless Network
Internet
Company intranet
FIREWALL
Leased modem pool
Security in WAP
FIR
EW
AL
L
WAP Security
WAP can secure communication between terminal and WAP gateway.
For communications between gateway and origin server, other means e.g. SSL are required.
GSM Security
Internet Security
35 © NOKIA FILENAMs.PPT/ DATE / NN
1. Choosing the movie
2. Choosing the payment method
3. Entering the PIN-code
4. Downloading tickets to the chip
5. Confirming the downloading and loyalty points
Future Example
36 © NOKIA FILENAMs.PPT/ DATE / NN
In the Cinema:
Printing the tickets from terminal with bluetooth
EMPS: Many ways to use it
37 © NOKIA FILENAMs.PPT/ DATE / NN
Corporate Impact
38 © NOKIA FILENAMs.PPT/ DATE / NN
• Currently there are 350 million mobile phone subscribers. By 2003 there will be more than 1 billion! Of these, around 600m are likely to be using WAP compatible products to access the web, compared to a PC installed base of around 400m
Cellular Phones Outnumber PCs
0
200
400
600
800
1000
1200
1997 1998 1999 2000 2001 2002 2003
Cellular Subscribers.Source: EMC 1999
PC installed base. Source: Dataquest 1999
39 © NOKIA FILENAMs.PPT/ DATE / NN
• Mobile phones are becoming media phones• WAP (Wireless Application Protocol) brings standard way to connect mobile
customers to content services
• Now near 300 million mobile phone users, by 2003 there will be more than 1 billion!
50 Milj.Users
RadioTV
WWWInternet
GSM
35 Years155
Today there are more than 150 million GSM subscribers world wide
WAP
Mobile Phone will be a new online Channel
40 © NOKIA FILENAMs.PPT/ DATE / NN
Is you’re organization ready?
• Mobile data is here today
• Accessibility• Modems
• Internal• External
• Internet Portal
• Encryption• WTLS• SSL• VPN
• Device
• Applications
41 © NOKIA FILENAMs.PPT/ DATE / NN
Terms
• 2G – Second Generation Phone Service – What we have today!
• 2.5G - GPRS
• 3G – Third Generation – Packet Switched Radio
• BTS – Base Transceiver Station
• BSC – Base Station Controller
• GGSN – GPRS Gateway Server Node
• HLR – Home Location Registry
• LIG – Lawful Interception Gateway
• MSC – Mobile Switching Center
• SMSc – Small Message Service Center
• PSTN – Public Switched Telephone Network
• SGSN – Serving GPRS Support Node
• VLR – Visitor Location Registry
42 © NOKIA FILENAMs.PPT/ DATE / NN
Questions?
Thank You for listeningThank You for listeningDanke für Ihre AufmerksamkeitDanke für Ihre Aufmerksamkeit
Kiitos huomiostanneKiitos huomiostanneMuchas gracias por atenciónMuchas gracias por atenciónMerci pour votre attentionMerci pour votre attention