How secure is your wireless network?


Wireless networks are a key risk area for companies that implement them, says David Halstead of Deloitte.

A number of independent surveys published recently have found that 60-70% of Wireless Local Area Networks (WLANs) are fundamentally insecure. Failure to implement adequate security controls allows, at the very least, all traffic over the WLAN to be monitored by an outsider, and poses a significant risk that must be managed. Some attacks are intended to seriously damage the systems and the network itself.

There are a number of steps that can be taken to reduce risk. For instance, security tools, which perform a security health check of WLANs such as Netstumbler (Windows) and Kismet (Linux), are freely available for download on the Internet.

Unauthorised access points are commonly found where users have set up their own unauthorised WLAN. Access points are as cheap as 130, a figure which could be expensed by an employee rather than budgeted as capital expenditure. The risk to the security of the network is heightened if the WLAN interfaces with the main company network.

Some important issues for CEOs to address with their IT Security team are:

  • Server Set ID (SSID)

    Most access points are configured with an SSID, which acts as a single key or password and is shared with all connecting wireless clients. An attacker can try to guess the base station SSID by using a bruteforce dictionary attack, which tries every possible word in the dictionary. Most WLANs' configuration passwords are simple to remember and easy to guess. The intruder can gain access through the base station by easily guessing the SSID.

  • Wired Equivalence Privacy (WEP)

    Physical wire networks, by their very nature, have a built-in layer of security. Wireless networks rely on a data encryption process to add this level of security. WEP is a commonly used encryption tool and CEOs should check with their IT Security team that WEP has been enabled.

    This is important because, by default, in most out-of-the-box access point models reviewed by surveys, WEP is not activated and traffic flowing on the WLAN is therefore open to view by all intruders.

    Active involvement by senior management is an important step in ensuring that wireless networks are not the weak link in the security chain, and that all wireless activity is governed by an adequate Wireless Security Policy.

    The topical subject of 'Security and the Internet' was the subject of a recent Cambridge Network Open Lecture. Read about the event

    deloitte logoDavid Halstead is a Partner at Deloitte in Cambridge. For more detailed information, please contact David or Dan Harris

    6 May 2004

    This article first appeared in Tangent, a fortnightly column offering business advice and comment

    The Deloitte Cambridge office comprises 8 Partners and over 250 staff who deliver a full range of professional services to the East Anglian region. As well as focussing on the life sciences and technology sectors for which the region has become so renowned, the office has long standing specialisms in other sectors including the professions, consumer business, food and agribusiness.

    Deloitte LLP