Lecture Information systems security - Chapter 4: Wireless network security

Wireless Network Security
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TJX Data Breach (Marshalls, T.J. Maxx,
HomeGoods, A.J. Wright…)
v

TJX used WEP
security

v

They
lost
45
million customer
records

v

They settled the
lawsuits for $40.9
million


Objectives
v

Describe the
protections

basic

IEEE

802.11

wireless

security

v

Define the vulnerabilities of open system authentication,
WEP, and device authentication

v

Describe the WPA and WPA2 personal security models

v

Explain how enterprises can implement wireless security


IEEE 802.11 Wireless Security
Protections
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IEEE
v

Institute of Electrical and Electronics Engineers (IEEE),
1963

v

In the early 1980s, the IEEE began work on developing
computer network architecture standards

v

This work was called Project 802

v

In 1990, the IEEE formed a committee to develop a
standard for WLANs (Wireless Local Area Networks)
v At that time WLANs operated at a speed of 1 to 2 million bits

per second (Mbps)


IEEE 802.11 WLAN Standard
v

In 1997, the IEEE approved the IEEE 802.11 WLAN
standard

v

Revisions
v IEEE 802.11 (2,4 GHz, 2 Mbps)
v IEEE 802.11a (5 GHz, 54 Mbps, 25- 75m)
v IEEE 802.11b (2.4 GHz, 11 Mbps, 35- 100m)
v IEEE 802.11g (2.4 GHz, 54 Mbps, 25- 75m)
v IEEE 802.11n (2.4 GHz, 5GHz, 300 Mbps, 50- 125m)


Controlling Access to a WLAN
v

Access is controlled by limiting a device’s access to the
access point (AP)

v

Only devices that are authorized can connect to the AP

v

One way: Media Access Control (MAC) address filtering

v

CSE uses this technique (unfortunately)


Controlling Access


MAC Address Filtering


Wired Equivalent Privacy (WEP)
v

Designed to ensure that only authorized parties can view
transmitted wireless information

v

Uses encryption to protect traffic

v

WEP was designed to be:
v Efficient and reasonably strong


WEP Keys
v

WEP secret keys can be 64 or 128 bits long

v

The AP and devices can hold up to four shared secret
keys

v

One of which must be designated as the default key



WEP Encryption Process


Transmitting with WEP


Device Authentication
v

Before a computer can connect to a WLAN, it must be
authenticated

v

Types of authentication in 802.11
v Open system authentication
v

Lets everyone in

v Shared key authentication
v

Only lets computers in if they know the shared key




Vulnerabilities of
IEEE 802.11 Security
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


Open System Authentication
v

To connect, a computer needs
the SSID (network name)

v

Routers normally send out
beacon frames announcing
the SSID

v

Passive scanning
v A wireless device listens for a

beacon frame


Turning Off Beaconing
v

For "security" some people turn off beacons

v

This annoys your legitimate users, who must now type in
the SSID to connect

v

It doesn't stop intruders, because the SSID is sent out in
management frames anyway

v

It can also affect roaming

v

Windows XP prefers networks that broadcast

MAC Address Filtering Weaknesses
v

MAC addresses are transmitted in the clear
v An attacker can just sniff for MACs

v

Managing a large number of MAC addresses is difficult

v

MAC address filtering does not provide a means to
temporarily allow a guest user to access the network
v Other than manually entering the user’s MAC address into

the access point


WEP
v

To encrypt packets WEP can use only a 64-bit or 128-bit
number
v Which is made up of a 24-bit initialization vector (IV) and a

40-bit or 104-bit default key
v

The 24-bit IV is too short, and repeats before long

v

In addition, packets can be replayed to force the access
point to pump out IVs


Cracking WEP
v

With the right equipment, WEP can be cracked in just a
few minutes

v

You need a special wireless card


Personal Wireless Security
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