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Cyber Security Tip ST05-003
Securing Wireless Networks
Wireless networks are becoming increasingly popular, but they introduce
additional security risks. If you have a wireless network, make sure to take
appropriate precautions to protect your information.
How do wireless networks work?
As the name suggests, wireless networks, sometimes called WiFi, allow you to
connect to the internet without relying on wires. If your home, office,
airport, or even local coffee shop has a wireless connection, you can access
the network from anywhere that is within that wireless area.
Wireless networks rely on radio waves rather than wires to connect computers
to the internet. A transmitter, known as a wireless access point or gateway,
is wired into an internet connection. This provides a "hotspot" that
transmits the connectivity over radio waves. Hotspots have identifying
information, including an item called an SSID (service set identifier), that
allow computers to locate them. Computers that have a wireless card and have
permission to access the wireless frequency can take advantage of the
network connection. Some computers may automatically identify open wireless
networks in a given area, while others may require that you locate and
manually enter information such as the SSID.
What security threats are associated with wireless networks?
Because wireless networks do not require a wire between a computer and the
internet connection, it is possible for attackers who are within range to
hijack or intercept an unprotected connection. A practice known as
wardriving involves individuals equipped with a computer, a wireless card,
and a GPS device driving through areas in search of wireless networks and
identifying the specific coordinates of a network location. This information
is then usually posted online. Some individuals who participate in or take
advantage of wardriving have malicious intent and could use this information
to hijack your home wireless network or intercept the connection between
your computer and a particular hotspot.
What can you do to minimize the risks to your wireless network?
* Change default passwords - Most network devices, including wireless
access points, are pre-configured with default administrator passwords
to simplify setup. These default passwords are easily found online, so
they don't provide any protection. Changing default passwords makes it
harder for attackers to take control of the device (see Choosing and
Protecting Passwords for more information).
* Restrict access - Only allow authorized users to access your network.
Each piece of hardware connected to a network has a MAC (media access
control) address. You can restrict or allow access to your network by
filtering MAC addresses. Consult your user documentation to get specific
information about enabling these features. There are also several
technologies available that require wireless users to authenticate
before accessing the network.
* Encrypt the data on your network - WEP (Wired Equivalent Privacy) and
WPA (Wi-Fi Protected Access) both encrypt information on wireless
devices. However, WEP has a number of security issues that make it less
effective than WPA, so you should specifically look for gear that
supports encryption via WPA. Encrypting the data would prevent anyone
who might be able to access your network from viewing your data (see
Understanding Encryption for more information).
* Protect your SSID - To avoid outsiders easily accessing your network,
avoid publicizing your SSID. Consult your user documentation to see if
you can change the default SSID to make it more difficult to guess.
* Install a firewall - While it is a good security practice to install a
firewall on your network, you should also install a firewall directly on
your wireless devices (a host-based firewall). Attackers who can
directly tap into your wireless network may be able to circumvent your
network firewallâ??a host-based firewall will add a layer of protection to
the data on your computer (see Understanding Firewalls for more
information).
* Maintain anti-virus software - You can reduce the damage attackers may
be able to inflict on your network and wireless computer by installing
anti-virus software and keeping your virus definitions up to date (see
Understanding Anti-Virus Software for more information). Many of these
programs also have additional features that may protect against or
detect spyware and Trojan horses (see Recognizing and Avoiding Spyware
and Why is Cyber Security a Problem? for more information).
_________________________________________________________________
Authors: Mindi McDowell, Allen Householder, Matt Lytle
_________________________________________________________________
Produced 2005 by US-CERT, a government organization.
Note: This tip was previously published and is being
re-distributed to increase awareness.
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