01 June 2004
The latest and greatest technology
Wireless solutions offer an inherently more secure infrastructure.
By Arturo Herrera
The ability to wirelessly transmit serial and Internet Protocol (IP) data over Ethernet is it.
That enables organizations to use new applications and services and gain access to information anytime, from anywhere.
Advancements in networking and communications have added risks, typically from individuals with less than honorable intentions when it comes to the information contained on a network. These risks can pose threats to industrial network infrastructures.
Securing the entire network is the ultimate goal, but the wireless portion of a network that uses built-in security layers can help enable end-to-end security throughout the network. This article will discuss different layers of security, including features available in wireless devices, such as RC4 128-bit encryption, automatic key rotation, two-way authentication, and finally the inherently secure nature of frequency hopping spread spectrum (FHSS) technology.
Transmit industrial protocols
Today, utilities' communication networks incorporate public, private, physical, and wireless infrastructure, all connected to the corporate network. The most recent development in industrial networking is the ability to transmit serial and industrial protocols over Ethernet in a wireless environment. Con-necting disparate networks (such as the corporate network with various supervisory control and data acquisition [SCADA] networks), hardware and software platform interoperability, collision avoidance, high transmission efficiency, and the ability to add new devices to a network without disrupting traffic flow are all benefits of this new practice. The use of IP over Ethernet also opens up new possibilities for integrating a utility-wide intranet, the World Wide Web, and/or video into a network. Products of this type have important applications in alarm and surveillance monitoring, including the transmission of video and other high-bandwidth traffic. Our focus here, however, is on securing the information traveling on the network.
Security has moved to the forefront as a critical element in data, voice, and video communications. Heightened awareness and sensitivity has led to increased security efforts. Although it is impossible to achieve and guarantee absolute security in wireless or wired networks, wireless networks can actually offer layers of security benefits that do not exist within a typical wired environment.
Cable-based systems that rely on telephone, fiber optics, or coaxial cables operate at a higher risk for breakage and damage from storms, motor vehicle accidents, construction work, and sabotage. Signal quality can also suffer, especially in older wired systems that have become noisy due to exposure and poor connections. Cable troubles can be difficult to locate, and repair depends on the priorities of maintenance crews. During a widespread event, such as a weather-related outage, repairs may have to wait for several days or even weeks while overloaded crews respond to other pressing incidents.
The availability of a wired network is also of concern, especially where the public telephone system is involved. During periods of heavy use, such as during a widespread emergency, it may not be possible to access the telephone network and get system data through. Voice traffic is always the priority, and unfortunately, in this scenario, the smooth operation of a network will be vital to organizations. It is important to note that cellular-based technologies, such as cellular digital packet data, are also subject to these limitations. Consumer voice traffic is the first priority of cell providers, not data services. Wired networks are vulnerable to accidental or intentional damage. It is impossible to ensure the integrity of the network.
Although no system can be 100% secure, wireless solutions offer an inherently more secure infrastructure, simply because there are no cables exposed to possible damage or sabotage by unauthorized persons. Wireless systems replace the cable infrastructure with an over-the-air radio frequency link. The main security issue with wireless networks, especially radio networks, is that wireless networks intentionally radiate data over an area the often exceeds the limits of the area the organization physically controls. Al-though wireless networks are susceptible to tapping if they platform on standards-based technology, through the use of custom hardware and software they can still be secure. Furthermore, additional levels of new securing technology combat risks to wireless network systems.
Security risks and mitigation
With the merger of corporate and control networks, security is becoming even more important. Password protection, firewalls, and virtual private networks (VPN) are three basic components of enterprise-level security that every company should have in place. Securing the network at the enterprise level is one layer. However, most security breaches do not enter through the company's front door security. Usually, there are back doors left open by contractors or disgruntled employees that allow a potential hacker to attack the systems without going through all the defenses that are normally set up to protect the corporate and SCADA networks. Most of the security breaches in SCADA networks happen due to serial modems attached to devices by contractors or employees looking to maintain a system. These leave holes for a hacker to attack a system and gain direct access to the network without having to hack the VPN, firewall, or router configurations. Built-in security features within 900-megahertz wireless devices can prevent the access of data transmission using wireless packet sniffers, interception and insertion of wireless information, unauthorized/unauthenticated devices from joining the network, denial of service attacks, Media Access Control (MAC) IP spoofing, and network topology discovery.
The readily available tools on the Web designed to hack into standards-based networks (802.11b WLAN) do not work with 900-megahertz solutions. Wi-Fi (2.4 gigahertz) devices came into being with interoperability as the goal and main feature, and this fact has proven to be a major security concern. For instance, 802.11b radio waves at 2.4 gigahertz easily penetrate building walls. An individual blocks away can receive and retrieve sensitive data by using the 802.11b wireless network interface card surreptitiously. Wireless devices operating in the 900-megahertz frequency range create a huge hurdle for hackers who only have access to this standards-based card.
In addition, most standards-based WLAN devices use direct sequence spread spectrum (DSSS) communications. Based upon that assumption, anyone with an 802.11b card can tune to the same spreading sequence and access data. Solutions that are 900 MHz alleviate this circumstance by using FHSS technology, which provides transmission security for military applications. Unlike DSSS, the carrier frequency changes several times per second, and to listen to data, one needs another radio set to the exact same pattern. Standards-based hacking devices cannot access information sent by radios equipped with FHSS.
Confidentiality of data is critical to industrial applications and now assured through the use of RC4 128-bit encryption and dynamic key rotation. The RC4 symmetric key algorithm from RSA Security masks data using a secret code that is unintelligible to unauthorized parties. Dynamic key rotation is a function of the encryption scheme that exists to prevent key cracking. The set of keys shared between radios changes periodically to further enhance security. Using privileged information, keys update and redistribute throughout the system. This information may include a pseudorandom seed value and a key identifier to indicate which secret key to modify.
It is virtually impossible to gain unauthorized network access because of the two-way authentication and provisioning list incorporated into some of the better designed wireless solutions. A network administrator can restrict connectivity between an access point (AP) and its remotes by ensuring the remote radios are on the AP's list of acceptable devices with which to communicate. The AP knows to accept communications only from remotes on its list. The same holds true for remote radios. If an unauthorized user is unable to authenticate, this prevents network topology discovery and MAC/IP spoofing.
So, and finally, security of a network is paramount when conducting business. It is important to remember there is no such thing as a completely secure network. Rather, security is something businesses can practice and not something exclusively bought. The advantages of an IP-based industrial network are evident in its innovative security features, both at the network and physical levels.
Wireless devices offering scalability, capability of supporting multiple users and applications on the same infrastructure, and security features for wireless data, voice, and video applications provide for an exciting innovation in wireless communication. Mitigating the risks involved with wirelessly transmitting critical data through built-in security features such as RC4 128-bit encryption, dynamic key rotation, two-way authentication, and FHSS can keep data and transactions secure. Basic safeguarding techniques such as password protection, firewalls capable of intrusion detection, packet filtering and proxy services, as well as a VPN all work together to secure networks further. Together, these solutions provide the layering necessary to supply full-spectrum security. W
Behind the byline
Arturo Herrera is a manager at Microwave Data Systems. Write him at firstname.lastname@example.org.