Syngress - Eleventh Hour Network+ Exam N10-004 Study Guide (11 ...

Common Exploits of Wireless Networks 67
■
(www.netstumbler.com). This type of scan, driving around looking for
wireless networks, is known as war driving.
Protecting against wireless network detection To defend against the use
of NetStumbler and other programs to detect a wireless network easily,
administrators should configure the wireless network as a closed system.
This means that the AP will not respond to empty set SSID beacons and
will consequently be “invisible” to programs such as NetStumbler, which
rely on this technique to discover wireless networks.
Crunch Time
Sniffing
Sniffing is the electronic form of eavesdropping on the
communications that computers transmit across networks.
Wireless networks function very similarly to the
original repeaters and hubs by allowing every communication
across the wireless network to be viewable to
anyone who happens to be listening to the network. In
fact, the person who is listening does not even need to
be associated with the network in order to sniff!
The hacker has many tools available to attack and monitor
a wireless network. These tools work well for sniffing
both wired and wireless networks. All of these software
packages function by putting your network card in what
is called promiscuous mode. When the network interface
controller is in this mode, every packet that goes past the
interface is captured and displayed within the application
window.
■
Protecting against sniffing and eavesdropping To protect wireless users
from attackers who might be sniffing is to utilize encrypted sessions wherever
possible: SSL for e-mail connections, secure shell (SSH) instead of
Telnet, and secure copy (SCP) instead of file transfer protocol (FTP). Additionally
turn off any network identification broadcasts and, if possible, close
down the network to any unauthorized users.
Active Attacks on Wireless Networks
The mechanisms used in active attacks can be comprised of a combination of
methods that ultimately result in an intruder being able to navigate his or her
way through the interworking of your network. Some possible attack methods
include the following:
■
■
Spoofing and network hijacking Usage of a legitimate IP address or MAC
address by an unauthorized device oftentimes resulting in the redirection
of legitimate data packets to the unauthorized device.
MITM through rogue APs Interception of network communications
through deployment of an AP with enough strength so that the end users
may not be able to tell which AP is the authorized one that they should
be using. Using this technique, the attacker is able to receive authentication
requests and information from the end workstation regarding the secret key
and where they are attempting to connect.