WLAN 802.11b Security FAQ

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Christopher Klaus

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Sep 24, 2002, 10:54:31 AM9/24/02

Wireless LAN Security FAQ

By Christopher W. Klaus of Internet Security Systems (ISS). Please
send corrections, additions, and new questions to cwkp...@iss.net.

Version 1.5 - Last Updated April 22st 2002
_________________________________________________________________

Contents

* [0] Where do I get the latest version of this Wireless LAN
Security FAQ?
* [1] What is the overview of Wireless LAN 802.11 technology?
+ [1.1] When will 802.11a arrive and how will the security be
different than 802.11b?
+ [1.2] What is an Access Point?
+ [1.3] How much does the equipment for wireless 802.11b cost?
+ [1.4] Are companies the only wireless targets by attackers?
+ [1.5] Where can you find wireless 802.11 networks?
+ [1.6] How does the antenna affect wireless LAN security?
o [1.6.1] How do I build a cheap and effective antenna?
+ [1.7] Can you spot a laptop with wireless 802.11 capability
by looking for the antenna?
* [2] What are the major security risks to 802.11b?
+ [2.1] What are Insertion Attacks?
o [2.1.1]Plug-in Unauthorized Clients
o [2.1.2]Plug-In Unauthorized Renegade Base Stations
+ [2.2] What are Interception and monitoring wireless traffic
attacks?
o [2.2.1] Wireless Sniffer
o [2.2.2] Hijacking the session
o [2.2.3] Broadcast Monitoring
o [2.2.4] ArpSpoof Monitoring and Hijacking
# [2.2.4.1] Hijacking SSL (Secure Socket Layer) and
SSH (Secure Shell) connections
o [2.2.5] BaseStation Clone (Evil Twin) intercept traffic
+ [2.3] What are AP and Client Misconfigurations?
o [2.3.1] Server Set ID (SSID)
# [2.3.1.1] What are the default SSID's?
o [2.3.2] What is Secure Access Mode?
o [2.3.3] Bruteforce Base Station SSID
o [2.3.4] Can the SSID be encrypted?
o [2.3.5] By turning off the broadcast of SSID, can
someone still sniff the SSID?
o [2.3.6] Wired Equivalent Privacy (WEP)
# [2.3.6.1] Attacks against WEP
# [2.3.6.2] Default WEP Keys
o [2.3.7] SNMP community words
# [2.3.7.1] SNMP Vulnerabilities
o [2.3.8] Configuration Interfaces
o [2.3.9] Client side security risk
o [2.3.10] Installation Risk
+ [2.4] What is Jamming?
o [2.4.1] 2.4 GHz Interfering Technology
+ [2.5] What are Client to Client Attacks?
o [2.5.1] Filesharing and other TCP/IP service attacks
o [2.5.2] DOS (Denial of Service)
o [2.5.3] Hybrid Threats
+ [2.6] War Driving Access Point Maps
+ [2.7] Parasitic Grids
* [3] What are solutions to minimizing WLAN security risk?
+ [3.1] Wireless Security Policy and Architecture Design
+ [3.2] Treat BaseStations as Untrusted
+ [3.3] Base Station Configuration Policy
o [3.3.1] 802.1X Security
+ [3.4] Base Station Discovery
+ [3.5] Base Station Security Assessments
+ [3.6] Wireless Client Protection
* [4] Who is making 802.11 Security Solutions?
+ [4.1] 802.11 Gateway Infrastructure
+ [4.2] 802.11 Security Analysis Tools
* [5] About Internet Security System's Wireless 802.11b Solution
_________________________________________________________________

Recent Updates

Version 1.5
* Added all of Netgear's default WEP keys.
* Added Pringles Can and Waveguide Antenna Info.
* Added hybrid threats, next-gen virus/worm spread by wireless.
* Added Parasitic Grids. Free anonymous access for intruders.
* Added SNMP vulnerabilities.
* Added 802.1X Security, and its flaws.
* Added MiniStumbler, Wireless Scanner, BlackICE PC Protection.
* Added info on Broadcast pings.

Version 1.3
* Added Section 1.7 regarding internal antenna.
* Added link to Cigital regarding ArpSpoofing. Cigital put together
a nice diagram of the attack.
* Added Default WEP key for NetGear AP.
* Added link to BSD version of AirSnort.

Version 1.2
* Added where this WLAN Security FAQ can be found.
* Cleaned up the formatting
* Added better indexing, added hyperlinks between index and content
* Added link to article on wireless LAN antennas

Version 1.1
* Added NetStumbler, WEPCrack tools, Added WEP insecurity paper
* Added Ecutel, BlueSocket, and NetMotion as WLAN Sec. Products
* Updated Accuracy of WEP description and made it clear that SSID
not being encrypted.
* Added Broadcast of SSID turned off can still be circumvented.
* Added Addtron's default SSID, a popular AP
* Added War Driving AP maps.
* Added 802.11 ArpSpoof, a technique used by ISS X-Force Consulting.
* Added hijacking SSH and SSL connections via wireless.
* Added 2 X-Force Advisories on Wireless 802.11 flaws

Version 1.0
* First draft
_________________________________________________________________

[0] Where do I get the latest version of this Wireless LAN Security FAQ?

* The most current version is on the Web at
http://www.iss.net/wireless
* It will be regularly posted to issf...@iss.net
(http://www.iss.net/maillists).

* It will be posted to the following Usenet newsgroups:
* comp.security.misc,comp.security.firewalls,comp.security.unix,
* comp.std.wireless,comp.dcom.sys.cisco,comp.dcom.sys.nortel,
* comp.dcom.telecom

[1] What is the overview of Wireless LAN 802.11 technology?

Wireless LAN technology standard 802.11b has the strongest momentum to
becoming the main standard for corporate internal wireless LAN
networks. The bandwidth of 802.11b is 11 mbits and operates at 2.4 GHz
Frequency. The successor of this current 802.11b standard is 802.11a
and it is designed to be faster speed and operate at a different
frequency. While 802.11a standard and the technology behind it will be
in the near distant future, 802.11b is here today and many companies
and even individuals are deploying and using it now.

As more wireless technology is developed and implemented, the
complexity of the types of attacks will increase, but these appear the
standard main methods used to break and attack wireless systems. These
attacks may be very similar against other wireless type technologies
and is not unique to 802.11b. By understanding these risks and how to
develop security solution for 802.11b, this will be a good
stepping-stone for providing a good secure solution to any wireless
solution.

[1.1] When will 802.11a arrive and how will the security be different than
802.11b?

Most manufacturers of wireless technologies are claiming to come out
with 802.11a technology either late 2001 or beginning of 2002. The
specifications for the protocols of 802.11a are very similar to
802.11b, therefore many of the security risks are shared for both
802.11a and 802.11b. Many of the security issues around 802.11b will
continue to be an issue with 802.11a, therefore by understanding
current issues will help organizations deal with future issues as
well.

[1.2] What is an Access Point?

The AP (access point also known as a base station) is the wireless
server that connects clients to the internal network. Base stations
typically act as a bridge for the clients. There is an IP address for
management configuration of the base station. The base stations
typically have an SNMP agent for remote management.

[1.3] How much does the equipment for wireless 802.11b cost?

Base stations have become relatively inexpensive, approximately under
$300US. The 802.11 client cards for PDAs, laptops, and desktops are
approximately under $100US. Because of inexpensive equipment to get
into wireless, attackers can get easy access to the tools necessary to
apply the attack. Because of the inexpensive price, within many
companies employees can purchase wireless equipment without approval
and deploy this in a rogue fashion, creating additional risk.

[1.4] Are companies the only wireless targets by attackers?

While this FAQ focuses on the risk issues from a corporate network
perspective, these same issues apply to home networks and
telecommuters that are using wireless. As the corporate networks are
allowing in remote users, these remote users may be using wireless at
their end-point to connect in. In this case, even if wireless
capabilities have not been installed on the corporate network, they
may still be affected by the risk that their remote employees are
using wireless at home or on the road.

[1.5] Where can you find wireless 802.11 networks?

Airports, hotels, and even coffee shops like Starbucks are deploying
802.11 networks so people can wirelessly browse the Internet with
their laptops. As these types of networks increase, this will create
additional security risk for the remote user if not properly
protected.

[1.6] How does the antenna affect wireless LAN security?

Because the intruder must be within range of the signal, a properly
selected and positioned antenna within a building can minimize how far
the signal can reach and therefore reduce leakage and interception.
For selecting different antenna designs for appropriate signal
reception, here is an article on wireless antennas:
* Antennas Enhance WLAN Security in Byte Magazine, October 2001.
* http://www.byte.com/documents/s=1422/byt20010926s0002/1001_marshal
l.html

[1.6.1] How do I build a cheap and effective antenna?

There are many people who are building cheap antennas with various
cheap cans bought at the grocery store including the Pringles can and
beef stew cans. The waveguide cans appear to be significantly
stronger in strength. Here is a good guide to building Pringles and
waveguide antennas:
* 802.11b Homebrew Antenna Shootout
* http://www.turnpoint.net/wireless/has.html

[1.7] Can you spot a laptop with wireless 802.11 capability by looking for the
antenna?

Many major computer manufacturers are now supporting built in wireless
802.11 capability and many new laptops are building an internal
wireless antenna. The physical antenna will not be easy to spot on all
laptops.

[2] What are the major security risks to 802.11b?

Here is the list of main known security risks with 802.11b:
* Insertion Attacks
* Interception and monitoring wireless traffic
* Misconfiguration
* Jamming
* Client to Client Attacks

[2.1] What are Insertion Attacks?

The insertion attacks are based on placing unauthorized devices on the
wireless network without going through a security process and review.

[2.1.1] Plug-in Unauthorized Clients

An attacker tries to connect their wireless client, typically a laptop
or PDA, to a basestation without authorization. Base stations can be
configured to require a password before clients can access. If there
is no password, an intruder can connect to the internal network by
connecting a client to the base station.

[2.1.2] Plug-in Unauthorized Renegade Base Station

Many companies may not be aware that internal employees have deployed
wireless capabilities on their network. An internal employee wanting
to add their own wireless capabilities to the network plugs in their
own base station into the wired intranet. This is a risk if the base
station has not been properly secured. This could lead to the
previously described attack of unauthorized clients then gaining
access to unauthorized base stations, allowing intruders into the
internal network. Typically, companies may need a policy against
allowing employees to add wireless base stations onto the corporate
network without requesting permission and going through a security
process. A sophisticated intruder may physical place a base station on
the victims' network to allow them remote access via wireless.

[2.2] What are Interception and monitoring wireless traffic attacks?

These interception and monitoring attacks are popular on broadcast
wired networks like Ethernet. The same principles apply to wireless.

[2.2.1] Wireless Sniffer

An attacker can sniff and capture legitimate traffic. Many of the
sniffer tools for Ethernet are based on capturing the first part of
the connection session, where the data would typically include the
username and password. An intruder can masquerade as that user by
using this captured information. An intruder who monitors the wireless
network can apply this same attack principle on the wireless.

One of the big differences between wireless sniffer attacks and wired
sniffer attacks is that a wired sniffer attack is achieved by remotely
placing a sniffer program on a compromised server and monitor the
local network segment. This sniffer based attack can happen from
anywhere in the world. Wireless sniffing requires the attacker to
typically be within range of the wireless traffic. This is usually
around 300 feet range, but wireless equipment keeps strengthening the
signal and pushing this range further out.

[2.2.2] Hijacking the session

If an attacker can sniff the wireless traffic, it is possible to
inject false traffic into a connection. An attacker may be able to
issue commands on behalf of a legitimate user by injecting traffic and
hijacking their victim's session.

[2.2.3] Broadcast Monitoring

If a base station is connected to a hub rather than a switch, any
network traffic across that hub can be potentially broadcasted out
over the wireless network. Because the Ethernet hub broadcasts all
data packets to all connected devices including the wireless base
station, an attacker can monitor sensitive data going over wireless
not even intended for any wireless clients.

[2.2.4] ArpSpoof Monitoring and Hijacking

Normally, in regards to an AP, the network data traffic on the
backbone of a subnet would be treated similarly like a network switch,
thus traffic not intended for any wireless client would not be sent
over the airwaves. This could reduce significantly the amount of
sensitive data over the wireless network.

An attacker using the arpspoof technique can trick the network into
passing sensitive data from the backbone of the subnet and route it
through the attacker's wireless client. This provides the attacker
both access to sensitive data that normally would not be sent over
wireless and an opportunity to hijack TCP sessions. Dsniff is a
popular tool that enables arpspoofing and is available at:
http://www.monkey.org/~dugsong/dsniff/

and Cigital has a diagram depicting the attack available at:
http://www.cigital.com/news/wireless/arppoison.gif

[2.2.4.1]Hijacking SSL (Secure Socket Layer) and SSH (Secure Shell)
connections.

By using arpspoofing technique, an attacker can hijack simple TCP
connections. There are tools that allow for hijacking SSL and SSH
connections. Typically, when SSL and SSH connections get hijacked, the
only alert to the end-user is a warning that the credentials of the
host and certificate have changed and ask if you trust the new ones.
Many users simply accept the new credentials, thus allowing an
attacker to succeed. A reasonable interim measure to prevent the
attack is to have users enable SSH's StrictHostKeyChecking option, and
to distribute server key signatures to mobile clients.

The Dsniff FAQ explains how to hijack in detail SSH and HTTPS
connections: http://www.monkey.org/~dugsong/dsniff/faq.html

[2.2.5] BaseStation Clone (Evil Twin) intercept traffic

An attacker can trick legitimate wireless clients to connect to the
attacker's honeypot network by placing an unauthorized base station
with a stronger signal within close proximity of the wireless clients
that mimic a legitimate base station. This may cause unaware users to
attempt to log into the attacker's honeypot servers. With false login
prompts, the user unknowingly can give away sensitive data like
passwords.

[2.3] What are AP and Client Misconfigurations?

By default, all the base stations analyzed out of the box from the
factory were configured in the least secure mode possible. Adding the
proper security configuration was left up as an exercise to the
administrator to lock down. Unless the administrator of the base
station understands the security risks, most of the base stations will
remain at a high risk level. The analysis of three base station models
by the leading 802.11 vendors lead to many configuration issues that
should be audited and assessed by the organization. The top three base
station vendors analyzed were Cisco, Lucent, and 3Com. The security
risks identified may change in newer versions of the 802.11 solution
as it is evolving rapidly. Each vendor had different implementation
security risks, but the underlying issues are the same and can be
applied to other vendors not listed here.

[2.3.1] Server Set ID (SSID)

SSID is a configurable identification that allows clients to
communicate to the appropriate base station. With proper
configuration, only clients that are configured with the same SSID can
communicate with base stations having the same SSID. SSID from a
security point of view acts as a simple single shared password between
base stations and clients.

[2.3.1.1] What are the default SSID's?

Each of the base station models came with default SSIDs. Attackers can
use these default SSIDs to attempt to penetrate base stations that are
still in their default configuration. Here are some default SSIDs:
* "tsunami" - Cisco
* "101" - 3Com
* "RoamAbout Default Network Name" - Lucent/Cabletron
* "Default SSID"
* "Compaq" - Compaq
* "WLAN" - Addtron, a popular AP
* "intel" - Intel
* "linksys" - Linksys
* "Wireless"

[2.3.2]What is Secure Access mode?

Lucent has Secure Access mode. This configuration option requires the
SSID of both client and base station to match. By default this
security option is turned off. In non-secure access mode, clients can
connect to the base station using the configured SSID, a blank SSID,
and the SSID configured as "any".

[2.3.3] Bruteforce Base Station SSID

Most base stations today are configured with a server set id (SSID)
that acts as a single key or password that is shared with all
connecting wireless clients.

An attacker can try to guess the base station SSID by attempting to
use a bruteforce dictionary attack by trying every possible password.
Most companies and people configure most passwords to be simple to
remember and therefore easy to guess. Once the intruder guesses the
SSID, they can gain access through the base station.

The SSID could be obtained through one of the wireless clients
becoming compromised or an employee resigns knowing the key, there is
risk that anyone with the SSID could still connect to the base station
until the SSID is changed. If there are many wireless users and
clients, it can become problematic to scale this security solution if
the SSID needs to be changed frequently and all clients and base
stations need to reconfigured with an updated shared single SSID each
time.

[2.3.4] Can the SSID be encrypted?

WEP, the encryption standard for 802.11, only encrypts the data
packets not the 802.11 management packets and the SSID is in the
beacon and probe management messages. The SSID is not encrypted if WEP
is turned on. The SSID goes over the air in clear text. This makes
obtaining the SSID easy by sniffing 802.11 wireless traffic.

[2.3.5] By turning off the broadcast of SSID, can someone still sniff the
SSID?

Many APs by default have broadcasting the SSID turned on. Sniffers
typically will find the SSID in the broadcast beacon packets. Turning
off the broadcast of SSID in the beacon message (a common practice)
does not prevent getting the SSID; since the SSID is sent in the clear
in the probe message when a client associates to an AP, a sniffer just
has to wait for a valid user to associate to the network to see the
SSID.

[2.3.6] Wired Equivalent Privacy (WEP)

WEP can be typically configured in 3 possible modes:
* No encryption mode
* 40 bit encryption
* 128 bit encryption

WEP, by default out of the box, all base station models analyzed have
WEP turned off. 40 bit encryption versus 128 bit encryption provides
no added protection against the known flaw in WEP.

Most public wireless LAN access points (i.e., airports, hotels, etc)
do not enable WEP. Based on statistical analysis in regions like New
York, San Francisco, London, Atlanta,

most companies do not turn on WEP security on their APs. If the AP
does not enable WEP, the wireless clients can not use the WEP
encryption.

In some base stations, it is optional whether the encryption is
enforced. The WEP encrypted may be turned on, but if it is not
enforced, a client without encryption with the proper SSID can still
access that base station.

[2.3.6.1] Attacks against WEP

802.11b standard uses encryption called WEP (Wired Equivalent
Privacy). It has some known weaknesses in how the encryption is
implemented.

Papers on WEP Insecurities
* Researchers at Berkeley have documented these findings at:
* http://www.isaac.cs.berkeley.edu/isaac/wep-faq.html
* Using the Fluhrer, Mantin, and Shamir Attack to Break WEP
* http://www.cs.rice.edu/~astubble/wep/wep_attack.html

Using WEP is better than not using it. It at least stops casual
sniffers. Today, there are readily available tools for most attackers
to crack the WEP keys. Airsnort and others tools take a lot of packets
(several million) to get the WEP key, on most networks this takes
longer than most people are willing to wait. If the network is very
busy, the WEP key can be cracked and obtained within 15 minutes.

The fix for encryption weakness for the standard is not slated to be
addressed before 2002.

Because of the WEP weakness, wireless sniffing and hijacking
techniques can work despite the WEP encrypted turned on.

There is the IEEE 802.1X standard which allows network access to be
authenticated and keys to be distributed. This allows access to APs to
be authenticated and WEP keys to be distributed and updated. More APs
are starting to support this standard.

[2.3.6.2] Default WEP Keys

The NetGear Access Point uses the following 4 WEP sequences as default
keys.
* 10 11 12 13 14
* 21 22 23 24 25
* 31 32 33 34 35
* 41 42 43 44 45

It is recommended not to use the default WEP keys.

Please e-mail cwkp...@iss.net if you know of other default WEP keys
for Access Points.

[2.3.7] SNMP community words

Many of the wireless base stations have SNMP (Simple Network
Management Protocol) agents running. If the community word is not
properly configured, an intruder can read and potentially write
sensitive information and data on the base station. If SNMP agents are
enabled on the wireless clients, the same risk applies to them as
well.

By default, all three base stations are read accessible by using the
community word, "public". With the default of most base stations using
the community word "public", potentially sensitive information can be
obtained from the base station.

By default, the 3com base station has write access by using the
community word, "comcomcom". Cisco and Lucent/Cabletron require the
write community word to be configured by the user before it is
enabled.

[2.3.7.1] SNMP vulnerabilities

Many implementations of SNMP were found to be vulnerable by using the
PROTOS tool developed by University of Oulu . This affected many
vendors, many of which produce wireless access points. Check with
your vendor and see if there is a firmware patch regarding SNMP
vulnerabilities. For more information on the testing tool for finding
SNMP issues, check here:
* http://www.ee.oulu.fi/research/ouspg/protos/
* http://www.iss.net/security_center/alerts/advise110.php

[2.3.8] Configuration Interfaces

Each base station model has its own interfaces for viewing and
modifying the configuration. Here are the current interface options
for each base station:
* Cisco - SNMP, serial, Web, telnet
* Lucent / Cabletron - SNMP, serial (no web/telnet)
* 3Com - SNMP, serial, Web, telnet.

3com base station lacks any access control from the web interfaces for
reading the configuration options. By connecting to the 3com base
station web interface, it provides SSID on the "system properties
menu" display. An attacker who finds a 3com base station web interface
can easily get the SSID.

3com base station does require a password on the web interface for
write privileges. The password is the same as the community word for
write privileges, therefore 3com base stations are at risk if deployed
using the default, "comcomcom" as the password. This gives an attacker
easy write access.

[2.3.9] Client side security risk

For the clients connecting to the base station, they store sensitive
information for authenticating and communicating to the base station.
If the client is not properly configured, access to this information
is available.
* Cisco client software stores the SSID in the Windows registry.
Cisco stores the WEP key in the firmware, which is difficult to
gain access to.
* Lucent/Cabletron client software stores the SSID in the Windows
registry. The WEP is stored in the Windows registry but it is
encrypted. The encryption algorithm is not documented.
* 3Com client software stores the SSID in the Windows registry. The
WEP key is stored in registry with no encryption.

Windows XP has 802.11 configuration and has a display of the available
SSID's built-in to the OS.

[2.3.10] Installation Risk

By default, all installations are optimized for the quickest
configuration to get users successful out of the box. Inversely, by
default, the installations are configured the least secure mode as
possible.

From out of the box experience, Cisco was simple and easiest to
install. 3Com installation was straight forward out of the box. And
Lucent/Cabletron had many firmware upgrades which led to confusion on
which upgrades to install.

[2.4] Jamming

Denial of service attacks for wired networks are popular. This same
principle can be applied to wireless traffic, where legitimate traffic
gets jammed because illegitimate traffic overwhelms the frequencies,
and legitimate traffic can not get through.

[2.4.1] 2.4 GHz Interfering Technology

An attacker with the proper equipment and tools can easily flood the
2.4 GHz frequency, so that the signal to noise drops so low, that the
wireless network ceases to function. This can be a risk with even
non-malicious intent as more technologies use the same frequencies and
cause blocking. Cordless phones, baby monitors, and other devices like
Bluetooth that operate on the 2.4 GHz frequency can disrupt a wireless
network.

[2.5] What are Client to Client Attacks?

Two wireless clients can talk directly to each other by-passing the
base station. Because of this, each client must protect itself from
other clients.

[2.5.1] Filesharing and other TCP/IP service attacks

If a wireless client, like a laptop or desktop, is running TCP/IP
services like a web server or file sharing, an attacker can exploit
any misconfigurations or vulnerabilities with another client.

[2.5.2] DOS(Denial of Service)

A wireless client can flood another wirelss client with bogus packets,
creating a denial of service attack. An attacker and sometimes
employees unintentionally can configure their client to duplicate the
IP or MAC address of another legitimate client causing disruption on
the network.

[2.5.3] Hybrid Threats

Next generation virus and worms have become a multi-vector attack
programs that self-propagate through any TCP/IP interface including
wireless. If one computer on a wireless network is infected with a
hybrid threat, this threat can easily spread to other wireless
computers and potentially internal computers behind the wireless
network.

[2.6] War Driving Access Point Maps

As people are "War Driving", and locating the APs and recording the
GPS coordinates of the AP location, these AP maps are being shared to
any attacker on the Internet. If a company has their AP location and
information shared on the Internet, their AP becomes a potential
target and increases their risk. One of the popular places to upload
War Driving AP maps, is to http://www.netstumbler.com. It includes a
visual map and a database query tool for locating various AP's.

[2.7] Parasitic Grids

From article, "An underground movement to deploy free wireless access
zones in metropolitan areas is taking hold... The movement, called
by some the "parasitic grid" and by others more simply the "free metro
wireless data network," has already installed itself in New York; San
Francisco; Seattle; Aspen, Colo., Portland, Ore., British Columbia;
and London..." This provides attackers and intruders completely
anonymous access. Trying to locate and trace attackers using the
parasitic grid becomes an impossible task.
* http://www.infoworld.com/articles/hn/xml/01/08/24/010824hnfreewire
less.xml

[3] What are solutions to minimizing WLAN security risk?

There are many options that organizations can do today to put proper
security protection around their wireless strategy and technology.

[3.1] Wireless Security Policy and Architecture Design

Many organization need to develop a wireless security policy to define
what is and what is not allowed with wireless technology. From a
holistic view, the wireless network should be designed with the proper
architecture to minimize risk.

[3.2] Treat BaseStations as Untrusted

From an network security architecture, the base stations should be
evaluated and determined if it should be treated as an untrusted
device and need to be quarinteed before the wireless clients can gain
access to the internal network. The architecture design may include
appropriately placing firewalls, VPNs, IDSes, vulnerability
assessments, authentication requirements between base station and the
Intranet.

[3.3] Base Station Configuration Policy

The wireless policy may want to define the standard security settings
for any 802.11 base station being deployed. It should cover security
issues like the Server Set ID, WEP keys and encryption, and SNMP
community words. Turning off broadcast pings on the Access Point
makes it invisible to 802.11b analysis tools like NetStumbler.

[3.3.1] 802.1X Security

Windows XP and many hardware vendors are building in 802.1X security
standards into their Access Points. This provides a higher level of
security than the typical WEP security. The 802.1x standard has a key
management protocol built into its specification which provides keys
automatically. Keys can also be changed rapidly at set intervals.
Check to see if your Access Points support 802.1X.

There have been some security flaws noted by security researches in
802.1X standard. This points out the need for good VPN technology
despite this new standard. Here is a document that outlines the issues
in 802.1X security:
* http://www.cs.umd.edu/~waa/1x.pdf

[3.4] Base Station Discovery

* From a wired network search, an organization could identify
unknown and rogue base stations by searching for SNMP agents. The
rogue base stations are identified as 802.11 devices through SNMP
queries for host id.
* Some base stations have a web and telnet interface. By looking at
the banner strings of these interfaces, this provides another
method of identifying some 802.11 devices.
* An additional means is by using unique TCP/IP attributes like a
fingerprint, it can help identify devices as base stations. Most
TCP/IP implementations have a unique set of characteristics and
many OS fingerprinting technologies use this method for
identifying the OS type. This concept can be applied to the base
stations.
* From a wireless network search, an organization can identify these
rogue base stations by simply setting up a 2.4 GHz sniffer that
identifies 802.11 packets in the air. By looking at the packets,
you may find the IP addresses to help identify which network they
are on. In a densely populated area with many businesses close
together, running a sniffer may pick up more the intended
organization's traffic, but a close neighboring company.

[3.5] Base Station Security Assessments

An organization can examine and analyze the base station
configuration. A security audit and assessment could determine whether
the passwords and community words are still default or easily guessed
and if better security modes have been enabled like encryption.

With router ACLs and firewall rules, an organization can minimize
access to the SNMP agents and other interfaces on the base station. A
security assessment can determine how widely accessible is the
configuration interfaces to the base stations are allowed to within
the organization.

[3.6] Wireless Client Protection

The wireless clients should be assessed for having the following
security technologies:
* firecell (distributed personal firewalls) - lock down who can gain
access to the client.
* VPN - adds another layer of encryption and authentication beyond
what 802.11 can provide.
* intrusion detection - identify and minimize attacks from
intruders, worms, viruses, Trojans and backdoors.
* desktop scanning - identify security misconfigurations on the
client.

[4] Who is making 802.11 Security Solutions?

[4.1] 802.11 Gateway Infrastructure

* BlueSocket: The WG-1000 Wireless Gateway(TM) offers a single
scalable solution to the security, quality of service (QoS) and
management issues facing enterprises and service providers that
deploy wireless LANs based on the IEEE 802.11b and Bluetooth(TM)
standards.
* EcuTel: Viatores Secure WLAN edition is different from legacy
virtual private networks (VPNs) in that it maintains VPN and
application sessions uninterrupted with no configuration or
re-boot required. Viatores combines two advanced protocols for
mobility and security to enable roaming from LANs to WLANs and
between WLAN subnets seamlessly and securely. Application sessions
and security tunnels are maintained while the user moves from one
subnet to another. Roaming users can communicate easily with
colleagues, regardless of where they are or how they are
connected, because Viatores maintains a single network address.
Viatores Secure WLAN edition includes:
+ Industry-strength secure communication well beyond the WEP
standard;
+ Seamless roaming from wired to wireless networks and between
different wireless networks;
+ Support for two-way, peer-to-peer communication;
+ Data confidentiality and integrity, including key exchanges,
digital signatures, and industry-strength encryption;
+ Option to upgrade to secure and seamless roaming from public
networks.
* NetMotion Wireless - NetMotion Mobility provides a VPN designed to
work with WLAN security.
http://www.netmotionwireless.com/resource/whitepapers/netmotion_se
curity.asp has an overview of wireless security and how NetMotion
Mobility(TM) prevents unauthorized users from accessing your
system and stops eavesdropping, replay, and other network-level
attacks.

[4.2] 802.11 Security Analysis Tools

* AirSnort is a wireless LAN (WLAN) tool that recovers encryption
keys. It operates by passively monitoring transmissions, computing
the encryption key when enough packets have been gathered.
AirSnort will work for both 40 or 128 bit encryption.
+ http://freshmeat.net/projects/airsnort/
+ http://www.dachb0den.com/projects/bsd-airtools.html
* WEPCrack is a to ol that cracks 802.11 WEP encryption keys using
the latest discovered weakness of RC4 key scheduling.
+ http://sourceforge.net/projects/wepcrack
* Network Stumbler scans for networks roughly every second and logs
all the networks it runs into--including the real SSIDs, the AP's
MAC address, the best signal-to-noise ratio encountered, and the
time you crossed into the network's space. If you add a GPS
receiver to the notebook, it logs the exact latitude and longitude
of the AP. Network Stumbler does not use promiscuous mode. Thus,
by simply turning off broadcast pings hides the Access Point from
NetStumbler. Now NetStumbler website includes a PocketPC
MiniStumbler.
+ http://www.netstumbler.com/
+ http://www.netstumbler.com/download.php?op=getit&lid=21
PocketPC MiniStumbler
* Internet Scanner 6.2, the market leading network vulnerability
assessment tool, was the first to assess many 802.11b security
checks. 802.11 checks are in several X-Press Updates (XPU 4.9 and
4.10). This is done by doing assessing via the wired network and
contacting the management interface.
* Wireless Scanner 1.0, designed to look for security issues via the
802.11b airwaves. Has a penetration testing mode and discovery
mode. Uses promiscuous mode, thus capable of capturing the raw
802.11b packets for forensics analysis and replay. Even if
broadcast pings are turned off, Wireless Scanner will still catch
any Access Points if it sends any kind of traffic due to using
promiscuous mode.
+ http://www.iss.net/download/ Evaluation copy of Wireless
Scanner.
+ https://iss.custhelp.com/cgi-bin/iss.cfg/php/enduser/home.php
WS1.0 Knowledge Base
* RealSecure 6.0, the market leading IDS, was the first to monitor
many 802.11b attacks. Recommend to make sure you are up to the
latest X-Press Updates. 802.11 checks for IDS were in XPU 3.1.
Recommend putting IDS behind the Access Point, directly on any
servers and desktops behind the access point, as well as, on any
wireless clients.
* BlackICE PC Protection 3.5, personal firewall with IDS capability,
is used on wireless laptops and desktops to protect against client
to client attacks.

[5] About Internet Security System's Wireless 802.11b Solution

ISS offers the comprehensive wireless security solution:
* Wireless Security Assessments and Penetration Testing
* Wireless Policy Design and Workshops
* Vulnerability Scanning with specific 802.11 configuration checks
* Intrusion Detection for Wireless LAN networks
* Wireless 802.11 Security Classes
* ISS X-Force Advisories:
+ http://xforce.iss.net/alerts/advise83.php 802.11 SNMP Auth.
Flaw
+ http://xforce.iss.net/alerts/advise84.php WEP Key exposed via
SNMP

This document may be redistributed only in its entirety with version
date, authorship notice, and acknowledgements intact. No part of it
may be sold for profit or incorporated in a commercial document
without the permission of the copyright holder. Permission will be
granted for complete electronic copies to be made available as an
archive or mirror service on the condition that the author be notified
and that the copy be kept up to date. This document is provided as is
without any express or implied warranty.

****
Christopher W. Klaus
Founder and CTO
Internet Security Systems
Email: cwkp...@iss.net

Christopher Klaus

unread,

Sep 30, 2002, 9:30:25 AM9/30/02

Wireless LAN Security FAQ

By Christopher W. Klaus of Internet Security Systems (ISS). Please
send corrections, additions, and new questions to cwkp...@iss.net.

Version 1.6 - Last Updated September 30th 2002
_________________________________________________________________

Contents

# [2.3.6.3] How Large is WEP Keys

o [2.3.7] SNMP community words
# [2.3.7.1] SNMP Vulnerabilities
o [2.3.8] Configuration Interfaces
o [2.3.9] Client side security risk
o [2.3.10] Installation Risk
+ [2.4] What is Jamming?
o [2.4.1] 2.4 GHz Interfering Technology
+ [2.5] What are Client to Client Attacks?
o [2.5.1] Filesharing and other TCP/IP service attacks
o [2.5.2] DOS (Denial of Service)
o [2.5.3] Hybrid Threats
+ [2.6] War Driving Access Point Maps
+ [2.7] Parasitic Grids
* [3] What are solutions to minimizing WLAN security risk?
+ [3.1] Wireless Security Policy and Architecture Design

o [3.1.1] Basic Field Coverage

+ [3.2] Treat BaseStations as Untrusted
+ [3.3] Base Station Configuration Policy
o [3.3.1] 802.1X Security
+ [3.4] Base Station Discovery

o [3.4.1] Honeypots - FakeAP

+ [3.5] Base Station Security Assessments
+ [3.6] Wireless Client Protection
* [4] Who is making 802.11 Security Solutions?
+ [4.1] 802.11 Gateway Infrastructure
+ [4.2] 802.11 Security Analysis Tools
* [5] About Internet Security System's Wireless 802.11b Solution

* [6] Acknowledgements
_________________________________________________________________

Recent Updates

Version 1.6
* Added new war driving maps.
* Updated 802.11a as being now available.
* Added how large is WEP key information.
* Added acknowledgements section
* Added Honeypots - FakeAP
* Add basic field coverage strategy

frequency. While 802.11a standard and the technology behind it has
become available, 802.11b is still widely used today and many
companies and individuals are deploying it or deploying dual 802.11b
and 802.11a devices.

[1.1] When will 802.11a arrive and how will the security be different than
802.11b?

Most manufacturers of wireless technologies have come out with 802.11a
technology now. The specifications for the protocols of 802.11a are

[2.1.1] Plug-in Unauthorized Clients

[2.2.1] Wireless Sniffer

[2.2.2] Hijacking the session

[2.2.3] Broadcast Monitoring

WEP turned off. 64 bit encryption versus 128 bit encryption provides

[2.3.6.1] Attacks against WEP

[2.3.6.2] Default WEP Keys

[2.3.6.3] How Large is WEP Keys

The original 802.11 specification defined a 40-bit key. This key is
combined with a 24 bit quantity known as the "initialization vector"
(which is created automatically by the wireless network hardware) and
these 64 bits are used within the RC4 encryption in order to produce
the encrypted data. Some vendors describe this as 64-bit encryption
(since technically RC4 is using 64 bits), but others describe it as
40-bits
(since the initialization vector is public unencrypted data so it does
not contribute to the security of the system). Therefore 40-bit and
64-bit WEP keys are the same thing, just being described from
different points of view. Most 802.11 hardware now supports a larger
104-bit key; this also has a 24-bit initialization vector and so it is
also sometimes marketed as a 128-bit system.

[2.3.7] SNMP community words

[2.3.7.1] SNMP vulnerabilities

[2.3.8] Configuration Interfaces

[2.3.10] Installation Risk

[2.4] Jamming

[2.5.2] DOS(Denial of Service)

[2.5.3] Hybrid Threats

target and increases their risk. They usually include a visual map and
a database query tool for locating various AP's. Here are some popular
places to upload War Driving AP maps.
* http://www.netstumbler.com.
* http://www.wigle.net
* http://www.wifimaps.com

[2.7] Parasitic Grids

[3] What are solutions to minimizing WLAN security risk?

There are many options that organizations can do today to put proper
security protection around their wireless strategy and technology.

[3.1] Wireless Security Policy and Architecture Design

[3.1.1] Basic Field Coverage

Because of wireless leakage, one of the first principals to basic
field coverage is to only provide coverage for the areas that you want
to have access.
By using directional antennas and lowering the transmit power (on
commercial class equipment - i.e., Cisco and Lucent), 85% (or higher)
of the typical 802.11 signal leakage can be effectively eliminated.

[3.2] Treat BaseStations as Untrusted

Wireless DMZ. This WDMZ includes appropriately placing firewalls,

VPNs, IDSes, vulnerability assessments, authentication requirements

between access point and the Intranet.

[3.3.1] 802.1X Security

[3.4] Base Station Discovery

[3.4.1] Honeypots - FakeAP

Black Alchemy's Fake AP generates thousands of counterfeit 802.11b
access points. Hide in plain sight amongst Fake AP's cacophony of
beacon frames. As part of a honeypot or as an instrument of your site
security plan, Fake AP confuses Wardrivers, NetStumblers, Script
Kiddies, and other undesirables.
* http://www.blackalchemy.to/Projects/fakeap/fake-ap.html

[3.6] Wireless Client Protection

[4.1] 802.11 Gateway Infrastructure

[6] Acknowledgements

This FAQ is written and maintained by Christopher Klaus. The following
people have
contributed to the FAQ. Their contributions are deeply appreciated.
* Skip Carter
* Gunter Ollmann
* Jim Broome
* Phil Brass

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