Vulnerability of Wireless Networks to Interception

This paper examines the vulnerability of wireless systems to interception, and provides some simple steps that can be taken to improve security. A commercially available computational electromagnetics software package was used to predict signal levels in complex indoor and urban environments. The simulation results can be used to determine the detection range of the network. Two basic scenarios are presented: (1) indoor-to-outdoor propagation for a local area network operating in a two story building, and (2) a wireless point-to-point link on an airbase. The simulations illustrate some of the unique propagation conditions that occur inside of buildings and in urban areas. This research has identified several possible system weaknesses and suggested some simple, yet effective, methods of improving security. Introduction A variety of wireless systems are used in both the civilian and military sectors. Some reasons for choosing wireless local area networks (WLANs) and point-to-point (PTP) systems over hardwired networks are their real-time information availability, achievable high bandwidths, resilience to failures, and simple and rapid installation (Boerner, 1995; Pahlavan, 1995). One concern in deploying systems that radiate in free space is the possibility of signals being intercepted by unauthorized users. The first step in the hacking process is to gain unauthorized access to network traffic. In many cases this is most easily accomplished by intercepting wireless signals. Authentication and encryption provide data security. Complex encryption techniques make it difficult for the average person to penetrate the system, however, the algorithms that are built into the network software have been defeated by knowledgeable hackers (Singhal, 2001; Conjungi, 2003). Although wireless security is vastly improved since the first generation systems, the threats continue to grow, and maintaining security is a constant challenge (ITworld, 2004). Predicting and subsequently controlling the electromagnetic radiation is an effective means of securing the network. In the case of WLANs, even though the power levels involved are low, a person in a public lobby or just outside of a building could conceivably tap into a system in a restricted area. Even for PTP systems that use directive antennas, the antenna illumination area on the ground (i.e., its “footprint”) increases with the range between two network nodes. Additionally, there are unique propagation conditions that occur Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE 2004 2. REPORT TYPE N/A 3. DATES COVERED 4. TITLE AND SUBTITLE Vulnerability of Wireless Networks to Interception 5a. CONTRACT NUMBER