GSM Security Feature, Threats and Solution

What is GSM?

Global System for Mobile Communications or widely known as GSM, is a digital mobile telephony system. GSM alters and compresses data. It will then be sent down to a channel with two other streams of user data, each in its own time slot. It operates at either the 900Mhz or 1800Mhz frequency band.

Security Features:

• Authentication - The user is identified by the network operator. This information along with the user's authentication key, includes sensitive identification credentials. The design of the GSM authentication and encryption schemes is such that, this sensitive information would never be transmitted over the radio channel. The network operator uses a challenge-response mechanism to confirm the user is not a fake.

• Signaling and Data Confidentiality - This protects voice, data and sensitive signaling information against eavsdropping on the radio path.

• Anonymity - This protects against someone tracking the location of the user. It also protects against someone identifying calls made to or from the user by eavesdropping on the radio path.

However, there are some problems with GSM security. Some examples are that, it only provides access security. This means that communications and signaling traffic in the fixed networks are not protected. Another example of the problem with GSM security is that is has a lack of user visibility. This means that for example, the user would not know if the authentication is encrypted or not.

GSM Threats:

• Eavesdropping

- This means that an intruder can intercept the traffic and signaling information to other users. The required equipment for eavesdropping would be a modified mobile phone.

• Impersonation of a User

- This means that there is a rogue data or signaling messages that was sent to the network with the intent of making them appear to be from another user. To impersonate another user also requires a modified mobile phone.

• Impersonation of the Network

- This means that there is a rogue data or signaling message that was sent to another user with the intent of making them appear from a real genuine network. To impersonate a network, it also requires a modified mobile phone.

• Man-In-The-Middle (MITM)

- This means that an attacker is put itself in between the network and the valid user in order to eavesdrop, modify, delete, re-order or even forge the signaling data between the two parties.

• Network Authentication Compromise

- This means that the intruder has a compromised authentication vector which may include challenge/response pairs, cipher keys and integrity keys. This data may have been taken by intercepting signaling messages on network links.

GSM Solutions:

• Securing the backbone traffic - Encrypting the traffic between the networks can prevent the attacker to eavesdrop or modify the transmitted data.
• Using secure algorithms - The network operators could perform improvement on themselves, without any need for the hardware and software manufacturers.
• Change to a more secured platform.

References:

www.cs.huji.ac.il/~sans/students_lectures/GSM%20Security.ppt

jazi.staff.ugm.ac.id/IC3-Royal%20Holloway/IC30304pt7.ppt

Threats and Countermeasures in GSM Networks