GPRS Security Feature, Threats and Solution

General Packet Radio Service security is the packet-switched extension to GSM, it is 2.5G, provides packet-switched data services, usually charges based on volume of data transmitted and it is suited to crowded traffic. Some of the applications would include typical data services like messaging, downloading, corporate LAN access and browsing. It allows the ability of users to use the same phone in a number of network-related countries, short message service which allows users to send and receive 126 characters text messages, allows data transmission and reception, fax transmission and reception across GSM network at a speed of 9600 bps, forwarding of calls to another number, conferencing of calls to multiple parties simultaneously. It allocates scarce radio resources more efficiently by supporting virtual connectivity, migrates traffic that was previously sent using circuit switched data to GPRS instead reducing SMS center and signaling channel loading by migrating some traffic that previously sent using SMS to GPRS instead of using the GPRS/SIM interconnect that is supported by the GPRS standards. GPRS is a new non-voice value added service that allows information to be sent and received across a mobile telephone network. Enabling GPRS on a GSM network requires the addition of two core modules, the Gateway GPRS Service Node and the Serving GPRS Node. GGSN acts as a gateway between GPRS network and Public Data Networks such as IP, it also connects to other GPRS networks to facilitate GPRS roaming. SGSN provides packet routing to and from the SGSN service area for all users in that service area. 

 

GPRS network connects to the Internet, corporate networks and other network service providers who provide services to subscribers. Subscribers are then exposed to viruses like worms, denial of service attaks, trojan horses and other malicious network traffic. Threats would include availability as attackers may be able to flood the link from PDN to the mobile operator with network traffic that prohibits legitimate traffic to pass, confidentiality as there is no protection of data from an MS to the public data network or corporate network, hence it is assumed that other parties are able to viewed the data if IP security or application layer security is not used. Authentication and authorization would also be a threat unless layer 2 or layer 3 tunnels are used at the GGSN to the corporate network, it is also possible for one MS to access the corporate network of another customer. Source address of network traffic cannot be relied upon for authentication and authorization purposes because MS or hosts beyond the MS can create packets with any addresses regardless of IP address assigned to the MS. Solutions to GPRS threats would be using logical tunnels from GGSN to corporate networks because it is not possible to route traffic from the Internet to a corporate network or between corporate network at all. In order to implement this, users have to make sure GGSN can logically separate corporate networks in layer 2 and layer 3 tunnels. If the connection to the corporate network is via the Internet, use IPSec to connect GGSN to the corporate network. Another way would be using traffic rate limiting because it prioritize IPSec traffic from corporate networks over that traffic on connections to Internet. This will ensure attacks from Internet cannot disrupt mobile intranet services, also consider using a separate physical interface for internet traffic separate from corporate internet traffic. 

References: 

http://www.it.iitb.ac.in/~kavita/GSM_Security_Papers/GPRS_Security_Threats_and_Solutions.pdf