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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 firewall--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
_________________________________________________________________
This document can also be found at
<http://www.us-cert.gov/cas/tips/ST05-003.html>
Copyright 2005 Carnegie Mellon University
Terms of use
<http://www.us-cert.gov/legal.html>
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