As laptops and personal devices get smaller and more mobile, wireless infrastructure is popping up everywhere to keep these devices connected. But, in the messy and chaotic 2.4GHz area of the radio wave spectrum – do you really know what, or more importantly, to whom you are connecting?
In a wired environment, you can usually see the end of your Ethernet cable. Someone with any level of security consciousness would find their four pairs of copper plugged into a wall jack or some other ‘friendly’ network device. If you were sitting in the airport waiting for a flight, it probably doesn’t sound like a good idea to plug your Ethernet cable into the laptop of the shady guy next to you in the hopes that you’ll be able to check your email. Every day, countless people (knowingly or unknowingly) plug right in – without the cable, of course.
Wireless security is not just encryption, authentication and filtering. There is a strong human component requiring some basic wireless awareness.
Fundamental Security Problems
If you plan to connect away from home, the familiar methods of security no longer apply. Things that keep trespassers out of your private home network like WPA, MAC filtering and SSID non-broadcasting are often counterproductive in a public hotspot. The purpose of a ‘public’ network is to invite people in, not keep them out. This presents several significant problems.
The fundamental problem of any public wireless network is just that: it is public. It is important to understand that regardless of any security measures put in place, wireless by nature is a ‘broadcast’ technology. Data is transmitted to anyone who will listen. Your laptop simply decides to ignore traffic destined to other devices on the wireless network because it is not the intended recipient of the data. There are numerous tools available that simply listen to what is received regardless of the intended recipient. Although this vulnerability alone does pose a security and privacy concern, most highly sensitive websites are ‘SSL’ encrypted (like web banking sites for example). Any captured data that is encrypted via SSL will be unreadable. For business and corporate users, this is usually not much of a concern either as they connect to the office using some form of VPN (Virtual Private Network). VPNs are essentially encrypted tunnels that help to protect sensitive data on its way across the public internet.
Although this fundamental public wireless security issue may be the most glaring, it is not necessarily the only thing that needs to be considered.
Not All Networks are Friendly
In a world without wires, how can you tell to what, or to whom, you have connected? The SSID (Service Set Identifier) is the primary way for end-users to identify a wireless network. It can be thought of as a simple name. There is no governing body distributing unique SSIDs. Users and administrators are free to ‘label’ their networks as they see fit. As you can imagine, this opens the possibility for someone to imitate or misleadingly label their network. For example, a name like ‘Free Wi-Fi’ or ‘Public Hotspot’ could be used. You may be wondering why someone would need to ‘spoof’ hotspots just to intercept your data. As mentioned previously, everything an individual transmits or receives is broadcast to all devices within the network. The real risk lies in having complete control of the internet connection, including the pages the individual may access. This opens up many possibilities including hosting what might appear to be a legitimate financial site in an attempt to gather sensitive information. What someone may think is a legitimate web site is actually being hosted on the attacker’s machine or network. There is also the potential to spread all sorts of malware to an unsuspecting visitor.
There has been a lot of press lately in regards to the ‘Free WiFi’ scam. An attacker would do the above mentioned simply by broadcasting an SSID like ‘Free WiFi’ or ‘Free Highspeed’ or something to that effect. In today’s digital ‘connected’ age, it is not difficult to find individuals willing to give these networks a try.
“How can I protect myself” you might ask? There are some very simple ‘low tech’ precautions that can be taken. One of the biggest things that all WiFi users (regardless of technical know-how) need to be familiar with is the difference between ‘Infrastructure’ and ‘Ad-hoc’ wireless networks.
Beware of Ad-hoc Networks
Ad-hoc devices, put simply, are other wireless enabled computers, not small boxes with antennae. The easiest way for someone to ‘spoof’ a valid network or to provide some ‘strings attached’ free internet is to use a laptop computer. The individual would simply go to a public location and broadcast an enticing SSID straight from their machine. It is important to note that you will be hard pressed to find a genuine public (or private) ad-hoc wireless network. They are rarely used. The single and perhaps most effective way to reduce your risk is to avoid Ad-hoc connections altogether. Most casual users will likely never find themselves in a situation where they need to connect to an Ad-hoc network.
In Windows XP and just about every 3rd-party wireless application, Ad-hoc networks are graphically represented differently from Infrastructure networks. Avoid them unless you know exactly who you are connecting to! When in doubt, avoid them completely.
The above image was taken from the built-in Windows XP wireless settings window. As you can see above, Infrastructure based networks are shown with what is supposed to be an antenna. The ‘Ad-hoc’ networks are displayed with what is supposed to be a removable laptop network card.
The above was taken from the latest Dell ‘Wireless Utility’. Again, there is a graphical distinction between Ad-hoc and Infrastructure points.
Aside from avoiding manual connections, you can also set your wireless utility to avoid automatic connections to Ad-hoc networks. Somewhere in your wireless tool, there will be an option like what is displayed below: (The below was taken from the ‘Advanced’ menu in Windows XP’s built in wireless tool)
Always ensure that you disable ‘auto connecting’ and ensure that only ‘Infrastructure’ networks can be used. This simple change will help keep you from connecting to something or someone you didn’t expect to.
Although avoiding Ad-hoc computer to computer connections helps significantly, not all infrastructure access points are legitimate either. If you are traveling—trying to get online at a hotel for example, call the front desk to inquire. Ask them what their network is called, and manually connect to it. This is especially important because many organizations do not have straight forward SSIDs. When in doubt, inquire. Same goes for an airport, coffee shop etc.
A little bit of awareness goes a long way.