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Smartening the Environment using Wireless
Sensor Networks in a Developing Country
Wireless Network Security
3G, 4G
Wireless PAN/LAN/MAN
Al-Sakib Khan Pathan
Department of Computer Science
International Islamic University Malaysia
UTM, 23 May 2012
Guided and Unguided Media
• All types of communications need some kind of
medium.
• The information is encoded in a signal that is
carried through a medium.
– Quality depends on the characteristics of the medium.
• Two main groups of transmission media, namely
the guided medium and the wireless medium.
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Guided and Unguided Media
• For the guided medium, there is a physical path
(such as a cable) for electromagnetic wave
propagation.
• For the wireless medium, the electromagnetic
wave is transmitted through air, water, or
vacuum (space).
• A wireless medium is also called an unguided
medium.
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Wireless LAN
• A wireless LAN or WLAN is a wireless local area
network that uses radio waves as its carrier.
• The last link with the users is wireless, to give a
network connection to all users in a building or
campus.
• The backbone network usually uses cables.
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Wireless Network? Security?
Source: http://www.pinellascomputers.com/wp-content/uploads/2011/07/wireless-networking-wifi-internet-setup.jpg
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Wireless Network Features
• Wireless networks are treated as having more
vulnerabilities than wired networks because of
their
–
–
–
–
shared nature
naturally broadcasted states
unclear perimeters
invisible access
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What other “Wireless”?
• 3G Wireless Networks
– 3G or 3rd generation mobile telecommunications is a
generation of standards for mobile phones and mobile
telecommunication services fulfilling the International
Mobile Telecommunications-2000 (IMT-2000)
specifications by the International Telecommunication
Union.
– Application services include wide-area wireless voice
telephone, mobile Internet access, video calls and
mobile TV, all in a mobile environment.
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What other “Wireless”?
• 4G Wireless Networks
– In telecommunications, 4G is the fourth generation of
cell phone mobile communications standards. It is a
successor of the third generation (3G) standards.
– 4G system provides mobile ultra-broadband Internet
access, for example to laptops with USB wireless
modems, to smartphones, & to other mobile devices.
– Conceivable applications include amended mobile
web access, IP telephony, gaming services, highdefinition mobile TV, video conferencing, 3D
television.
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3G Wireless
Source: http://www.topglobalusa.com/images/j041.gif
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A Cell Tower
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3G and WiFi
S: http://www.cryptech.com.au/wp-content/uploads/2010/03/difference-between-3g-mobile-broadband-and-wifi-wireless-network.png
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What they have in Common?
• Wireless unguided medium.
• Potential threat from anybody within the range of
wireless coverage/communication.
• Attenuation.
• Distortion during signal propagation.
• Noises.
• Do all of these impact security?
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Security Viewing Angles
• Viewing Angle 1
–
–
–
–
(a) Key Management
(b) Secure Routing
(c) Secure Services
(d) Intrusion Detection Systems (IDS) [outsider, insider]
• Viewing Angle 2
–
–
–
–
–
(a) Physical security
(b) Deployment security (sparse or dense, etc.)
(c) Topological security (cluster/flat, hierarchy/tree, etc.)
(d) Wireless communication security
(e) Data security
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Security Viewing Angles
• Viewing Angle 3: Holistic Security
–
–
–
–
–
(a) Application layer security
(b) Transport layer security
(c) Network layer security
(d) Data link layer security
(e) Physical layer security
• Holistic Security? – Still open research issue!
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Main Security Aspects
•
•
•
•
•
Authentication
Authorization
Privacy/Confidentiality
Integrity
Non-repudiation
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3G Security: Background
• One of the aspects of GSM that has played a
significant part in its global appeal is its set of
security features
• GSM was the first public telephone system to
use integrated cryptographic mechanisms
• GSM security model has been adopted, modified
and extended for DECT, TETRA and 3GPP
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3GPP
• The 3rd Generation Partnership Project (3GPP)
is a collaboration between groups of
telecommunications associations, known as the
Organizational Partners.
• The initial scope of 3GPP was to make a
globally applicable 3G mobile phone system
specification based on evolved Global System
for Mobile Communications (GSM) specifications
within the scope of the International Mobile
Telecommunications-2000 project of the ITU.
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3GPP Security Principles
• Ensure that 3G security builds on the security of
GSM where features that have proved to be
needed and that are robust shall be adopted for
3G
• Ensure that 3G security improves on the security
of second generation systems by correcting real
and perceived weaknesses
• Ensure that new 3G security features are
defined as necessary to secure new services
offered by 3G
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3G Security Objectives
• Ensure that
– information generated by or relating to a user is
adequately protected against misuse or
misappropriation.
– the resources and services provided are adequately
protected against misuse or misappropriation.
– the security features standardized are compatible with
world-wide availability.
– the security features are adequately standardized to
ensure world-wide interoperability and roaming
between different serving networks.
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3G Security Objectives
• Ensure that
– the level of protection afforded to users and providers
of services is better than that is provided in
contemporary fixed and mobile networks (including
GSM).
– the implementation of 3GPP security features and
mechanisms can be extended and enhanced as
required by new threats and services.
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3G Requirements Capture
• Based on the threat analysis, a comprehensive
list of security requirements were captured and
categorized
• The security requirements help identify which
security features need to be introduced in order
to counteract the threats
• The requirements capture has led to the
identification of additional security features
beyond those retained from GSM
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3G Security Arch: Background
Source:
Peter Howard ,
Vodafone, UK
Presentation Slides
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3G R99 Security Features
(beyond GSM)
• Protection against active attacks on the radio
interface
– New integrity mechanism added to protect critical
signaling information on the radio interface
– Enhanced authentication protocol provides mutual
authentication and freshness of cipher/integrity key
towards the user
• Enhanced encryption
– Stronger algorithm, longer key
– Encryption terminates in the radio network controller
rather than the base station
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3G R99 Security Features
(beyond GSM)
• Core network security
– Some protection of signaling between network nodes
• Potential for secure global roaming
– Adoption of 3GPP authentication by TIA TR-45 /
3GPP2
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3G Security Architecture
Home Environment (HE)
Serving Network (SN)
Access Network (AN)
Mobile Terminal (MT)
Terminal Equipment (TE)
User Services Identity Module (USIM)
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3G Network Architecture
Circuit
Network
Circuit/
Signaling
Gateway
Feature
Server(s)
Circuit
Switch
IN Services
RNC
Voice
Radio
Access
Control
Mobility
Manager
Data +
Packet
Voice
Call
Agent
IP Core
Network
Packet
Gateway
Packet Network
(Internet)
IP RAN
Intelligent Network (IN)
Radio Network Controller (RNC)
IP Radio Access Network (IP RAN)
2G
2G/2.5G
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3G
Source: Presentation Slides of
Myagmar, Gupta: UIUC, USA, 2001
26
Improved Security Features, 1
• Network Authentication
– The user can identify the network
• Explicit Integrity
– Data integrity is assured explicitly by use of integrity
algorithms
– Also stronger confidentiality algorithms with longer
keys
• Network Security
– Mechanisms to support security within and between
networks
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Improved Security Features, 2
• Switch Based Security
– Security is based within the switch rather than the
base station
• IMEI Integrity
– Integrity mechanisms for IMEI (International Mobile
Equipment Identity) provided from the start
• Secure Services
– Protect against misuse of services provided by SN
and HE
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Improved Security Features, 3
• Secure Applications
– Provide security for applications resident on USIM
• Fraud Detection
– Mechanisms to combating fraud in roaming situations
• Flexibility
– Security features can be extended and enhanced as
required by new threats and services
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Improved Security Features, 4
• Visibility and Configurability
– Users are notified whether security is on and what
level of security is available
– Users can configure security features for individual
services
• Compatibility
– Standardized security features to ensure world-wide
interoperability and roaming
– At least one encryption algorithm exported on worldwide basis
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Improved Security Features, 5
• Lawful Interception
– Mechanisms to provide authorized agencies with
certain information about subscribers
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Problems of 3G Security, 1
• IMSI (International Mobile Subscriber Identity) is
sent in cleartext when allocating TMSI
(Temporary Mobile Subscriber Identity) to user.
• The transmission of IMEI (International Mobile
Equipment Identity) is not protected; IMEI is not
a security feature.
• A user can be enticed to camp on a false BS.
Once the user camps on the radio channels of a
false BS, the user is out of reach of the paging
signals of SN.
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Problems of 3G Security, 2
• Hijacking outgoing/incoming calls in networks
with disabled encryption is possible. The intruder
poses as a man-in-the-middle and drops the
user once the call is set-up.
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4G Security?
• Two issues are at the forefront of 4G
development:
– the verification of users and
– the limitation of network access in the heterogeneous
architecture.
• Other vulnerabilities involve providers utilizing
different systems and the basis of user-centered
design, which allows users to select their
preferred connection method.
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Wireless PAN
• WPAN?
– A wireless personal area network (WPAN) is a
personal area network - a network for interconnecting
devices centered around an individual person's
workspace - in which the connections are wireless.
•
•
•
•
•
•
IrDA (Infrared Data Association)
Bluetooth
Wireless USB
Z-Wave
ZigBee
Body Area Network
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Wireless LAN/MAN
• WLAN?
– Wireless connected LAN.
• WMAN?
– A metropolitan area network (MAN) is a computer
network that usually spans a city or a large campus. A
MAN usually interconnects a number of local area
networks (LANs) using a high-capacity backbone
technology, such as fiber-optical links, and provides
up-link services to wide area networks (or WAN) and
the Internet. Wireless Version!!
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What About Security?
• Common solutions may work in each type of
network.
• Basic wireless security barriers are present but
based on characteristics and network settings,
things may be different and may demand
specific security measures.
• Based on different standards, different security
requirements are met.
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What About Security?
Two security services are mainly emphasized:
• Authentication
– Shared Key Authentication
• Privacy/Confidentiality (Encryption)
– Wired Equivalence Privacy
• Other aspects are often requirement specific.
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WLAN Security?
• 802.11 standard specifies the operating
parameters of wireless local area networks
(WLAN)
– History: 802.11, b, a, g, i
• Minimal security in early versions.
• Original architecture not well suited for modern
security needs.
• 802.11i attempts to address security issues with
WLANs.
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IEEE 802.11b
• Wired Equivalent Privacy (WEP)
– Confidentiality
• Encryption
– 40-bit keys (increased to 104-bit by WEP2)
– Based on RC4 algorithm
• Access Control
– Shared key authentication + Encryption
• Data Integrity
– Integrity checksum computed for all messages
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IEEE 802.11b
• Vulnerabilities in WEP
– Poorly implemented encryption
• Key reuse, small keys, no keyed MIC
– Weak authentication
– No key management
– No interception detection
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IEEE 802.11b: Attacks
• Successful attacks on 802.11b
– Key recovery - AirSnort
– Man-in-the-middle
– Denial of service
– Authentication forging
– Known plaintext
– Known ciphertext
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IEEE 802.11i
• IEEE 802.11i-2004 or 802.11i, implemented as
WPA2 (Wi-Fi Protected Access II), is an
amendment to the original IEEE 802.11.
• The draft standard was ratified on 24 June 2004
• Later amendments in 2007 and 2012!
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Original IEEE 802.11i
• Security Specifications
– Improved Encryption
• CCMP (AES), TKIP (Temporal Key Integrity Protocol), WRAP
(Wireless Robust Authenticated Protocol)
–
–
–
–
2-way authentication
Key management
Ad-hoc network support
Improved security architecture
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802.11i Authentication
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802.11 Encryption
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802.11i: Potential Weaknesses
• Hardware requirements
– Hardware upgrade needed for AES (Advanced
Encryption Standard) support
• Strength of TKIP and WRAP questionable in the long term
– AS (auth. server) needed for 2-way authentication
• Complexity
– The more complex a system is, the more likely it may
contain an undetected backdoor
• Patchwork nature of “fixing” 802.11b
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Connecting WLAN – Control?
• Options:
– May be connected securely (WPA2, 802.11i, etc.)
– If unsecured, connect to your secure systems
securely:
• VPN – Virtual Private Network
• SSL connections to secure systems
– Be careful not to expose passwords
– Watch for direct attacks on untrusted networks
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802.11i Improvements
• 802.11i appears to be a significant improvement
over 802.11b from a security standpoint
• Vendors are nervous about implementing
802.11i protocols due to how quickly WEP was
compromised after its release
• Time will tell how effective 802.11i actually is
• Wireless networks will not be completely secure
until the standards that specify them are
designed from the beginning with security in
mind
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Remarks – WLAN Security
• Wireless LAN Security also could be
benefited by the advancements of security
measures for other networks.
• The main reason that WLANs are attacked
is due to their availability for long time and
the medium used, where anybody can try
to join in.
• All these apply to PAN and MAN as well!!
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References
[1] Marius Popovici, Daniel Crisan, Zagham Abbas, "Wireless
Networks",
http://ftp.utcluj.ro/pub/users/cemil/rlc/Wireless%20Networks.ppt
[2] Peter Howard, "3G Security Overview", Presentation Slides,
Vodafone, UK
[3] http://www.3gpp.org/ftp/Specs/html-info/FeatureOrStudyItemFile60150.htm
[4] Colin Blanchard, "Security for the Third Generation (3G) Mobile
System", Network Systems & Security Technologies.
[5] Myagmar, Gupta , “3G Security Overview”, Presentation Slides of
UIUC 2001.
[6] Kim W. Tracy, "Wireless LAN Security", NEIU, University Computing
www.neiu.edu/~ncaftori/355/Wireless.ppt
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THANK YOU
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Questions and Answers
[email protected] , [email protected]
http://staff.iium.edu.my/sakib/
???
http://staff.iium.edu.my/sakib/ndclab
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