confidential and proprietary capturing air: tools and methods to make wireless assessments a breeze...

Confidential and Proprietary

Capturing Air: Tools and Methods to Make Wireless Assessments a

Breeze

Leo Walsh, GSNA

Professional

Jefferson Wells


Topics

• Auditing Mindset

• Wireless Basics

• Wireless Security Issues

• Typical Wireless Architectures

• Auditing Wireless Networks


Why are you here?

• You might be required to do a wireless audit.

• You want to learn more about wireless security.

• You would like to learn how to secure your home wireless router.

• You hope the presenter will show you how to hack into your neighbor’s wireless router.

• Your company is paying for your lunch at the Hereford house.


Auditing Mindset – Common Ground

• Independent Cooperative

• Appraisal Assurance

• Enemy Team Mate

• Auditing is measuring

• Answers the question, “How do you know?”


Auditing Mindset – Working with IT

IT thinks they are:

•“Just Fine”

•“The Experts”

•“Overworked”

•“Secure”

Auditors think IT is:

•“Insecure”

•“Stubborn”

•“Aloof”

•“Arrogant”


Auditing Mindset – Working with IT

• Obtain Wireless information up front– SSID– Network Architecture

• Wireless Device Configurations and Model #’s• IP Addresses• Internet Connectivity• Corporate Network Connectivity

– Risk Mitigation Techniques– Remote Management– Logging and Monitoring Procedures– Authentication and Encryption Methods


Wireless Basics – Terms

• Access Point– An access point connects multiple

wireless devices much like a hub or switch. Most wireless routers are access points

• End Point– An end point connects to an access

point or another end point. Computers are the most common end points.



• Open Network– An open network can be accessed by any

end point. The data transmitted on the open network is not encrypted and can be read by anyone with a wireless device. When using an open network users are very susceptible to attack and information leakage. If required to use an open network immediately connect to a VPN or use only SSL sites. The Jefferson Wells VPN does not encrypt HTTP traffic for web sites on the Internet.



• WEP Encrypted Network– WEP stands for Wired Equivalent

Privacy. It was designed to provide the same level of privacy a user could expect when connecting to a LAN. The wireless traffic on a WEP network is encrypted using an inferior encryption scheme. It is easy for potential attackers to obtain the encryption key and decrypt WEP traffic.



• WPA Encrypted Network– WPA stands for WiFi Protected

Access. WPA is far superior to WEP. Traffic on a WPA wireless network is encrypted using a simple password. It is difficult (but not impossible) to guess this password and decrypt WPA traffic. WPA replaced WEP in 2003.



• SSID– SSID stands for service set

identifier which is used to identify that a particular packet is assigned to the network associated with that SSID.



• BSS– BSS stands for basic service set. It

is composed of at least 2 devices with the AP acting as the master control.

• ESS– ESS stands for extended service

set. It is a set of one or more interconnected BSS’s with the same SSID.



• WLAN– WLAN stands for Wireless Local

Area Network

• Wi-Fi– Wi-Fi is a brand name owned by the

Wi-Fi Alliance, a group of independent companies that have agreed upon certain standards in order to ensure interoperability



• 802.11– 802.11 is the generic IEEE standard for

WLAN communication. The number is followed by a letter (like a, b or g) to describe a specific standard.

• 802.1x– 802.1x is the IEEE standard for network

access control (authentication). It is frequently confused with 802.11 standards. 802.1x standards are frequently used in WLAN implementations.



• Radio Frequency (RF)– RF is the rate of oscillation of a

radio wave. 802.11 applies to the frequencies of 5 GHz and 2.4 GHz, which are both public sector bands.

• Signal Strength– The signal strength of a RF devices

is measured in watts. The higher the strength the larger the distance covered by the RF device. Modern AP’s range from 32 mW to 200 mW.


Wireless Security Issues

• Radio waves can penetrate walls and be reflected unintentionally

• Signal leakage is a common occurrence

• Can’t detect someone listening to your signal

• Distance is determined by antenna quality – both AP and EP

• Poor encryption• Poor authentication• Devices can be very small


Wireless Security Issues – Location

• Keep in mind what is physically near the AP– Parking lot– Park– Deli / Coffee House– Other buildings or offices

• Keep in mind what is physically distant from the AP– Mountain / Hill– Tall building


Wireless Security Issues – WEP

• WEP uses a very poorly implemented encryption scheme (RC4)

• The WEP key is easy to guess using freely available tools

• WEP has been proven to be obsolete (incredibly worthless) since 2001

• Original version used only a 40 bit key which was changed to a 104 bit key

• Active attacks can dramatically reduce the amount of time required to obtain the key for cracking purposes


Wireless Security Issues – WEP Myths

• New WEP implementations – WEP+, WEP2, Dynamic WEP – fixed the problem

• It takes a very long time to obtain enough information to crack the encryption key

• Using 128 bit WEP is safe• Certain WEP keys are

unbreakable


Wireless Security Issues – Cracking WEP

• Simple process

• Very well described on the Internet

• Freely available tools and drivers

• New tool requires very few packets

• Can be done from long distances


Wireless Security Issues – Cracking WEP – Active Attack

1. Obtain hardware and software to support WEP cracking

2. Place wireless device within range of WEP network to capture traffic

3. Use tool to force end point to disconnect from network

4. Listen for special packet on reconnect

5. Replay packet until enough information is gathered

6. Run tool to obtain WEP key7. Decrypt all WEP traffic


Wireless Security Issues – Cracking WEP – Passive Attack

1. Obtain hardware and software to support WEP cracking

2. Place wireless device within range of WEP network to capture traffic

3. Listen for enough packets to obtain key

4. Run tool to obtain WEP key5. Decrypt all WEP traffic


Typical Wireless Architectures

• Open on public network

• Closed on public network

• Filtered on public network

• Closed on corporate network

• Closed and segregated on corporate network


Typical Wireless Architectures - Open on Public Network

Internet

Corporate


Typical Wireless Architectures - Closed on Public Network

Internet

Corporate


Typical Wireless Architectures - Filtered on Public Network

Internet

Corporate


Typical Wireless Architectures - Closed on Corporate Network

Internet

Corporate


Typical Wireless Architectures - Closed and segregated on corporate network

Internet

Corporate


Auditing Wireless Networks – High Risk First

• Start with assessing the highest/most common risks first– Misconfiguration– Poor encryption– Unapproved devices– Bad implementation


Auditing Wireless Networks – Tools

• Free tools to get the job done:– Network Stumbler

www.netstumbler.com– Aircrack-ng Suite

www.aircrack-ng.org– BackTrack v2.0 Live CD

www.remote-exploit.org/backtrack.html


Auditing Wireless Networks – Hardware

• Check your chipset– Not all chipsets support injection– May have to download a tool to determine– Good info at:

http://www.aircrack-ng.org/doku.php?id=compatible_cards

• Check driver support for OS and application

• Atheros chipset best supported with drivers for Windows and Linux

• Consider an antenna or GPS


Auditing Wireless Networks – NetStumbler

• Windows only• Monitors signal strength• Lists SSID, MAC addresses, etc• Can be used to monitor and log

wireless activity• Can be used to detect wireless

devices– Locate device in list then monitor– Roam around using signal strength

as “hot” or “cold” indication


Auditing Wireless Networks – NetStumbler


Auditing Wireless Networks – Aircrack-ng Suite

• Set of wireless tools mostly designed to crack encryption

• Windows and Linux (although some tools are Linux only)

• Contains a packet sniffer, packet injector, capture file decoder, tunnel interface and multiple crackers

• Used to list SSID’s in range• Prove that WEP is too weak to use in

any scenario


Auditing Wireless Networks – Aircrack-ng Suite


Auditing Wireless Networks – Steps

1. Obtain wireless network information from IT• Configuration and Models• Architecture• SSID• Encryption and Authentication• Mitigation• Logging and Monitoring• Administration

2. Confirm information obtained using manual review of configuration files and wireless tools

3. Provide results and possible recommendations back to IT for comment

4. Provide final report to management


Auditing Wireless Networks – Questions to ask

• What type of encryption are we using?• Is there any 802.1x authentication

configured for the WLAN?• Are connections to the WLAN logged?• Is important data transmitted over our

wireless networks?• What security parameters or configurations

are in place?• What is our SSID?• What is our WPA or WEP key and how is it

protected?


Auditing Wireless Networks – Questions?

Any Questions?

confidential and proprietary capturing air: tools and methods to make wireless assessments a breeze...

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