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Q&A: Locking Down Wireless Networks



Md Sohail Ahmad, a senior wireless security researcher at AirTight Networks, which develops wireless security products, recently talked with Dr. Dobb's editor in chief Jon Erickson about the state of wireless security.

Dr. Dobb's: What's unique about wireless security?

Ahmad: Wireless brings a fundamental paradigm shift to security in that the network access and data transmission is now over the air which is a shared and unbounded medium (radio waves spill way beyond your premises). This means that without appropriate security, it's very easy for an unauthorized user sitting in the parking lot outside your building or even few blocks away to steal your data in the air and similarly to gain access to your organization's network through the air. The Wi-Fi (802.11) is an open standard, operates in unlicensed frequency band, and hardware and software is available off-the-shelf, which maximizes this risk. This risk is absent in wired networks.

Dr. Dobb's: What's the biggest wireless threat?

Ahmad: Wi-Fi access points (APs) are inexpensive and available off the shelf. Most portable computers like laptops and netbooks as well as smartphones (e.g., iPhone, Blackkberry) and consumer devices (e.g., printers) come with Wi-Fi built in. These devices are flooding the enterprise, in turn putting enterprise security into the hands of end-users more than ever before. End-users could inadvertently (or maliciously) put enterprise security at risk, for instance, by plugging in an unsecured Wi-Fi AP into the enterprise network, or sharing their enterprise network access with outsiders over Wi-Fi. This threat from unmanaged, unsecured Wi-Fi devices and the flood of Wi-Fi endpoints into the enterprise and the lack of awareness among administrators and users about it, is the biggest wireless threat.

Dr. Dobb's: What's the biggest security mistake companies make?

Ahmad: As far as wireless security is concerned, the biggest mistake organizations can make is to apply wired network security philosophy and solutions to implement wireless security. Often network administrators make the mistake of thinking that having solid wired security is enough to take care of Wi-Fi security risks. On the contrary, unsecured Wi-Fi attached to the enterprise network, can open a backdoor for hackers to enter the wired enterprise network while completely bypassing all wired security measures such as firewalls, wired IDS/IPS, and content filters.

Dr. Dobb's: Are there emerging wireless security standards?

Ahmad: Given that Wi-Fi transmissions are over the air, the security of inflight wireless data starts with strong encryption and authentication. The earliest Wi-Fi security protocol was the Wired Equivalent Privacy (WEP) protocol, which is now known to be broken; the latest is Wi-Fi Protected Access version 2 (WPA2), which uses the advanced encryption standard and 802.1x based authentication. While WPA2 has so far done its job in protecting Wi-Fi networks from outsiders, a flaw in the protocol that was recently demonstrated at BlackHat Arsenal 2010 and Defcon18 exposes WPA2-secured Wi-Fi networks to insider attacks.

Dr. Dobb's: How safe are airports for wireless users?

Ahmad: Not only are airports rife with Wi-Fi hotspots that are used by travelers, but many businesses and critical operations (e.g., baggage handling, ticketing) are increasingly relying on Wi-Fi. This makes airports a prime target for Wi-Fi based attacks. AirTight Networks has conducted a Wi-Fi security study by scanning over 30 airports worldwide. The report from this study is available here. Most Wi-Fi hotspots on airports use Open Wi-Fi configuration which is extremely insecure for Wi-Fi users. Given the well-known risks of using Open Wi-Fi, some hotspot providers (e.g., Tmobile) are migrating to the WPA2 protocol for Wi-Fi security. But travelers using these hotspots should beware of the recently uncovered Hole196 vulnerability in the WPA2 protocol that exposes the inherent lack of inter-user data privacy among authorized users of a WPA2-secured Wi-Fi network. Details of WPA2 Hole196 vulnerability are available here.

Dr. Dobb's: What' s the easiest thing companies can do to enhance wireless security?

Ahmad: Like any security, there are no shortcuts to wireless security. Companies should follow some best practices to protect their networks from wireless vulnerabilities and threats:

  • Use WPA2 (AES and 802.1x) to secure your Wi-Fi network from outsiders.
  • Use a wireless intrusion prevention system to continuously monitor your airspace and proactively detect, block, and locate threat-posing Wi-Fi devices or those that may be violating your company's security policy.
  • Educate end users about risks from careless use of Wi-Fi on their endpoints on premises or on the road, such as at airports and coffee shops.

Here is a check list of best practices for wireless computing on public networks:

  1. Remove undesirable wireless networks from your wireless network connection profile
  2. Remove any peer to peer network from your wireless network connection profile
  3. Connect only to trusted networks which are known to you
  4. Disconnect immediately if you accidentally connect to an unknown network
  5. Turn off your wireless card when you do not need to be connected over wireless
  6. Use a VPN client when connecting over insecure public Wi-Fi hotspots
  7. When a VPN client is not available, use a secure Web browser (SSL)
  8. Avoid accessing confidential, sensitive or valuable information over unencrypted connections
  9. Upgrade your Wireless software regularly. Always keep your laptop's wireless drivers updated to the latest version
  10. Review points 1 - 9 every time you are connecting wirelessly


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