MBWS Tutorial

GSM Security Feature, Threats and Solution

Security Feature

The reason of having security is to make sure the GSM system is as secure as the Public Switched Telephone Network (PSTN) and also to make sure that phone cloning is not allow and GSM uses air for transmission media so it will allow quite a number of potential threats from eavesdropping.

So the following is the Security Feature:

• Subscriber Identity Protection using Temporary Mobile Subscriber Identity (TMSI) which is assigned to each mobile phone
• User anonymity - Designed to protect the user against someone, from tracking the location of the user or to identify calls made to or from that user by eavesdropping on the radio path
• Key Management Scheme - Ki – Subscriber Authentication Key uses 128 bit key for authentication of user by operator. 
• Detection of Compromised Equipment using International Mobile Equipment Identifier (IMEI), Equipment Identity Register (EIR) and Central Equipment Identity Register (CEIR).

• Subscriber Authentication is to protect the network against unauthorized user, by challenge-response authentication of users by operator.
• Signaling and user data protection used to protect data and signaling over the radio path

Threats

• Microwave Links - Link between BS and BSC is a point to point microwave link so this link can be eavesdropped.
• False Based Station - MS is authenticated to the BS, but BS is not authenticated to MS, so GSM provides unilateral authentication. Hence it will allows attacks on mobile user by allow user to connect to a Fake Based Station. But setting up a Based station is expensive so this threat is very rare.
• Denial of service (DoS) attack will cause the network not to transmit messages or causing the network to send messages it should not. The network will not be able to distinguish real traffic from a fake traffic.

Solution

• Subscriber Authentication is to protect the network against unauthorized user, by challenge-response authentication of users by operator.

Using Spatscheck it will have three key points for preventing DoS attack

• Accounting for all consumed resources per client
• Detection when any client uses too much resources
• Containment it will reclaim the tied resources after detection by dedicating minimum additional server resources to the task and thus preventing a follow up attack.

GPRS Security Feature, Threats and Solution

Security Feature

The security feature of GPRS is very similar to GSM standard

• Identity Confidentiality to provide privacy to the user, a Temporary Logical Link Identifier (TLLI) is used that is combined with Routing Area Identity (RAI) to avoid ambiguities, and the identity is stored in the database in each SGSN.
• Identity Authentication it is done by the SGSN. Pairs of Random Numbers and Signed respones (RAND & SRES) is gathered from the HLR/AUC and kept by the SGSN.
• Signaling and user data protection used to protect data and signaling over the radio path

Threats

• GGSN exhaustion: Attackers can creates and forwards GTP commands (i.e., PDP Context Create, Delete or Update) to a GGSN, overloading it and changing the servicing contexts of users. This results in denial of service (DoS).
  

• Hackers will release viruses, trojans, malware and spyware as GPRS is designed to allow users to use the internet and the terminal equipment will be 'always on' and it has software like internet browsing and email application, that mean the equipment will be attack from viruses. Hence the software which can execute computer code so it allow code to be downloaded to the equipment and it can monitor user usage, making calls unknown to the user etc. 

Solution

• There are a range of antivirus software developed programmed to scan for viruses and firewalls can be used to prevent this attack from happening.

References

Christos Xenakis, D. A. (n.d.). A Qualitative Risk Analysis for the GPRS Technology. Retrieved Jan 04, 2012, from A Qualitative Risk Analysis for the GPRS Technology: citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.148

Howard, P. (n.d.). IIR-Overview. Retrieved Jan 04, 2012, from IIR-Overview: http://www.isrc.rhul.ac.uk/useca/OtherPublications/IIR-overview.pdf

Kröger, C. (n.d.). GSM security. Retrieved Jan 04, 2012, from GSM security: http://www.google.com.sg/url?sa=t&rct=j&q=gsm%20security%20features&source=web&cd=30&ved=0CHQQFjAJOBQ&url=http%3A%2F%2Freferaat.cs.utwente.nl%2FTSConIT%2Fdownload.php%3Fid%3D951&ei=eVkFT_7tJoXPrQf6md2sAQ&usg=AFQjCNEhtsXtzplEp5Pu5b2G206fBojhZg&cad=rja

 

Stepanov, M. (n.d.). GSM Security Overview . Retrieved Jan 04, 2012, from GSM Security Overview : www.cs.huji.ac.il/~sans/students_lectures/GSM%20Security.ppt