1. GSM, UTMS, Wi-Fi and some Bluetooth
G53SEC
Mobile Security
GSM, UTMS, Wi-Fi and some Bluetooth 1

2. Security in the mobile world GSM 3GPP / UTMS Mobile IPv6 Wi-Fi
G53SEC
Today’s Lecture:
Security in the mobile world
GSM
3GPP / UTMS
Mobile IPv6
Wi-Fi
Bluetooth 2 2

3. Mobile computing one of the fastest growing segments of the PC market
G53SEC
Introduction:
Mobile computing one of the fastest growing segments of the PC market
What is a mobile network?
Changing physical / geographical location
Changing network topology
Attached somewhere to a fixed network
Wireless communication 3 3

4. What is different about mobile networks?
G53SEC
Introduction:
What is different about mobile networks?
Low bandwidth – minimise message size and volume
Increased risk of eavesdropping
Security issues
Authentication
Privacy
Charging 4 4

5. Mobile services pose new challenges Some derive from technology
G53SEC
Introduction:
Mobile services pose new challenges
Some derive from technology
Some from applications
Physical access – no longer a barrier to network
- Wi-Fi access to corporate networks
Technology – easier eavesdropping
Wifi – e.g. attacker in car park 5 5

6. Current most active mobile technologies GSM 3GPP/UTMS Mobile IP
G53SEC
Introduction:
Current most active mobile technologies
GSM
3GPP/UTMS
Mobile IP
IEEE
Bluetooth
Mbile IP – allow mobile devices to move from one network to another while maintaining a permanent IP address 6 6

7. Other areas of mobile networks with security implications
G53SEC
Introduction:
Other areas of mobile networks with security implications
WAP – Wireless Application Protocol
Malicious scripting, Infrastructure issues
SMS – Short Messaging Service
Spam, spoofing, viruses
MANETs – Mobile Ad-hoc Networks
- Rogue nodes, Security only at academic stage
Wap (wireless application protocol) – tried to be internet of wireless – failed
Sms – short messaging service
Mobile adhoc network – self-configuring network of mobile devices 7 7

8. G53SEC
GSM – Cell Towers: 8 8

9. 1st Generation Cell Phones Charge fraud – simple authentication
G53SEC
GSM:
1st Generation Cell Phones
Charge fraud – simple authentication
Alibi creation – call forwarding
GSM – Improvement from 1st generation
Good voice quality
Cheap end-systems
Low running costs
etc.. 9 9

10. Creation affected by political influences
G53SEC
GSM:
Creation affected by political influences
Differing national regulations and attitudes towards cryptography
Law enforcement requested ability to wiretap
GSM security goals
Protection against charge fraud
Protection of voice and signal traffic
Phone theft tracking
Phone theft tracking not always implemented 10 10

11. GSM user – subscriber in home network
G53SEC
GSM:
Components
GSM user – subscriber in home network
Where service requested – serving network
Mobile station comprises
Mobile equipment
Subscriber Identity Module (SIM)
SIM card – smart card chip
Performs cryptographic operations
Stores keys
Stores personal data 11 11

12. IMSI – International Mobile Subscriber Identity
G53SEC
GSM:
IMSI – International Mobile Subscriber Identity
Unique subscriber identification
TMSI – Temporary Mobile Subscriber Identity
Used to avoid location tracking
Served when device joins a new subnet
IMSI catchers
Device authenticates to network but not vice versa
Catcher masquerades as a base station
Collects IMSI numbers
TMSI – used to avoid location tracking
Catcher – used by law enforcement and intelligence agencies to eavesdrop
Catcher – a type of man-in-the middle attack 12 12

13. Uses symmetric cryptography 3 algorithms
G53SEC
GSM:
Cryptography
Uses symmetric cryptography
3 algorithms
A3 – authentication (Provider specific)
A5 – encryption (Standardised)
A8 – key generation (Provider specific)
No official publication of algorithms exists
Cryptanalytic attacks do exist 13 13

14. Location Based Services
G53SEC
GSM:
Location Based Services
GSM network records location information of mobile equipment
Used for various services (e.g. traffic info)
Used for emergencies (Medical, Police, etc…)
Obligatory in some countries (e.g. the US)
Privacy implications 14 14

15. GSM does not transmit secrets in the clear
G53SEC
GSM Summary:
GSM does not transmit secrets in the clear
Voice traffic encrypted over radio but not after base station
Some privacy protection through TMSI
but IMSI catchers exist to avoid TMSI
Law enforcement has access to recorded location data
TMSI – Temporary Mobile Subscriber Identity 15 15

16. Cryptographic algorithms not made public Unilateral authentication
G53SEC
GSM Summary:
Criticism:
Cryptographic algorithms not made public
Unilateral authentication
Only mobile equipment authenticates to the network
Fraud:
Revenue flow attacked
Roaming fraud
Premium rate fraud
TMSI – Temporary Mobile Subscriber Identity 16 16

17. Universal Mobile Telecommunications System Next generation of GSM
G53SEC
3GPP/UTMS:
Universal Mobile Telecommunications System
Next generation of GSM
Besides technical advancements, contains some security enhancements
Security architecture similar to GSM
Avoids IMSI Catchers
- Due to mutual authentication of mobile equipment to the network and vice versa 17 17

18. Support for mutual authentication Privacy Increased key sizes
G53SEC
3GPP/UTMS:
Authentication
Support for mutual authentication
Privacy
Increased key sizes
Support for securing core network signalling data
Enhanced user identity confidentiality
Other
Integrity of signalling
Cryptographic algorithms made public 18 18

19. In IP if nodes move around:
G53SEC
Mobile IPv6:
GSM & UTMS have problems with access control due to lack of pre-established relationship
In IP if nodes move around:
- When IP address kept, data will not reach node at new location
- When IP address changes, communication has to be terminated and restarted
Mobile IP deals with these issues 19 19

20. Mobile node has two addresses permanent Home Address
G53SEC
Mobile IPv6:
Mobile node has two addresses
permanent Home Address
Care of Address – associated with network the node is visiting
Addresses consist of location as well as interface identification 20 20

21. Home agent – nodes with permanent address within agent's network
G53SEC
Mobile IPv6:
Home agent – nodes with permanent address within agent's network
Foreign agent – nodes visiting network
When a node wants to communicate with another node, it uses its home address
Packets sent are intercepted by Home agent
Home agent uses care-of address advertised by Foreign Agent to communicate with destination node 21 21

22. A number of security protocols proposed WEP WPA WPA2
G53SEC
Wi-Fi:
Wireless technology generally based on a set of standards called IEEE
A number of standards (a,b,g,n) exist depending on speed and technological improvements
A number of security protocols proposed
WEP
WPA
WPA2 22 22

23. G53SEC
WiFi: 23 23

24. Wi-Fi Increasingly used at home and as part of businesses
G53SEC
Wi-Fi:
Wi-Fi Increasingly used at home and as part of businesses
New uses emerge frequently
City wide Wi-Fi
BT FON 24 24

25. Incorrectly setup Access Points Encryption Access control
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Wi-Fi:
Many Issues:
Incorrectly setup Access Points
Encryption
Access control
Wi-Fi not included in security policies in many institutions
- Weak encryption standards used
- Rogue Access Points
- War-driving 25 25

26. Key size a major security limitation
G53SEC
Wi-Fi:
WEP
Key size a major security limitation
Algorithm is susceptible to a cryptanalysis attack
It uses the RC4 stream cipher algorithm
WEP allows certain packet parts to be reused
This allows attacker to obtain some known text
The rest is only a matter of statistical analysis 26 26

27. 2007 – WEP cracked under 60 seconds by researchers from Germany
G53SEC
Wi-Fi:
WEP
Original attack required hours of collected data to successfully find encryption key
2007 – WEP cracked under 60 seconds by researchers from Germany
WPA
A quick preliminary solution to WEP issues
However vulnerable to a password guessing attack 27 27

28. A complete redesign of WLAN security mechanisms
G53SEC
Wi-Fi:
WPA2
A complete redesign of WLAN security mechanisms
Stream cipher RC4 replaced by AES
but WPA2 requires new hardware
To Remember:
For Wi-Fi access points only use WPA2 or in worst case WPA
WEP is totally broken! 28 28

29. Technology for wireless ad-hoc networks For short range communications
G53SEC
Bluetooth:
Technology for wireless ad-hoc networks
For short range communications
e.g. for keyboards, headsets, etc..
Contains cryptographic mechanism for traffic protection between devices
Application level attacks exist
Bluesnarf exploits flawed implementations of access control – retrieves personal information
Viruses are beginning to appear 29 29

30. Security in the Mobile environment Current mobile technologies
G53SEC
Summary:
Security in the Mobile environment
Current mobile technologies 30 30