Wireless Security

Nilesh Sapariya CEH v8 , CCNA

Security Engineer

About me :

Agenda

1) Introduction to WLAN Security

2) WLAN Architectures

3) WPA / WPA2 PSK (Personal) Cracking

WLAN

1 ) In computing, Wireless LAN or Wireless Local Area Network is a term to refer to a Local Area Network that does not need cables to connect the different devices.

2) Instead, radio wave are used to communicate

From Fixed Device to Mobile Device

These Device’s don’t have LAN Port

Only and Best Mode of Connectivity

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D D D D

D D D OO

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Wireless is a more efficient, many-to-one access method

AP

O

“Right-sized” Edge (One port supports multiple users and devices simultaneously)

With Wi-Fi Ports Can Be Easily Cut In Half

7

L

12 VOIP phones7 Desktop PC’s5 Laptop PCs

1 Wireless AP (mobile devices, guests, etc.)

6 Conference room & public area ports5 Other devices (printer, copier, fax, etc.)12 Ports (reserved for future use)

D

V

F

O

C

AP

V VVV V V

V VVV V V

D D D D

D D D

AP

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O O F F FFFF

F F FFFF

L L L LL

C C C C C CO

Existing Wired Network Edge (1:1 ratio of ports to devices)

Representative 12-person Workgroup

Wi-Fi Comes Problem

Challenging Wi-Fi

Environment

Client DensityAnd

Diversity Challenges

Security againstUncontrolled Wireless

Devices and Infrastructure attacks

RF Noise Metal Objects with Wheels

Building Materials

Security Risk

Uncontrolled Wireless Devices• Rogue APs• Laptops acting as bridges• Misconfigured WLAN Settings on laptops• Ad-Hoc networks

Attacks against WLAN infrastructure• Denial of Service/flooding• Man-in-the-Middle• WEP (Wired Equivalent Privacy ) cracking (aircrack-ng –

famous tool)• WPA/WPA2 ( Wireless protected access ) cracking

(aircrack-ng – famous tool)

Security Risk

Ad HocAccess Point MAC

Spoofing

?

Server

Rogue User

Mis-configured Access Point

Office

And More such kind of Attacks

Wireless Standards - 802.11a, 802.11b/g/n, and 802.11ac

• 1997 IEEE ( Institute of Electrical and Electronics Engineering ) created First WLAN

• Called as 802.11 • 802.11 only supports max network BW = 2

Mbps (to slow for most of application )

WLAN Operation

• Wireless LAN (WLAN) Can operate in 2 different frequency ranges

• 2.4GHz (802.11 b/g/n ) • 4.9 or 5GHz (802.11 a/h/j/n)• Note : your wireless card can only be on one

channel ( it has single radio ) • Every country has allowed channel ,users and

maximum power levels

• Fair distribution of clients across channels

• eg. Channel 1, 6, 11

• Fair distribution of clients across bands

• eg. 2.4-GHz and 5-GHz

Channel 11

Channel 6

Channel 1

WLAN Setup

802.11a/b/g/n

Antennas

Policy

Mobility

Forwarding

Encryption

Authentication

Management

“Fat” Access Point”

Centralized Management Centralized Security

“Thin” Access Points

Policy

Mobility

Forwarding

Encryption

Authentication

Management

802.11a/b/g/n

Antennas

Many devices to manage Many entry points to secure

Centralized Mobility Controller

Wardriving

• How to find SSID in your area • How to find hidden SSID • Tools used :-i. inSSIDerii. Common view for wifi

Understanding WPA / WPA2 (Wi-Fi Protected Access )

Wireless Encryption

• The main source of vulnerability associated with wireless networks are the methods of encryption. There are a few different type of wireless encryption including:

• WEP• WPA• WPA2

WEP

• Stands for Wired Equivalent Privacy.• WEP is recognizable by the key of 10 or

26 hexadecimal digits.

WPA or WPA2

• Stands for Wi-Fi Protected Access• Created to provide stronger security• Still able to be cracked if a short password is

used. • If a long passphrase or password is used, these

protocol are virtually not crackable.• WPA-PSK and TKIP or AES use a Pre-Shared

Key (PSK) that is more than 7 and less than 64 characters in length.

Why WPA ?

WEP (Wired Equivalent Privacy )broken beyond repair

if you are using 64 bit or 128 bit key WEP will be broken

Weaknesses of WEP

1. Poor key management

• WEP uses same key for authentication/encryption• Provides no mechanism for session key refreshing• Static Key encryption used

2. One-way authentication

WEP Replacement

Long Term Solution Use CCMP ( Counter Mode Cipher

Block Chaining Message Authentication Code Protocol )

Based on AES Hardware Change Require

Personal Enterprise Personal Enterprise

Intermediate solution by Wifi-Alliance

Use TKIP (Temporal Key Integrity Protocol )

Based on WEP Hardware change not required Firmware update

PSK PSK802.1x + Radius 802.1x + Radius

WPA WPA2

Difference between WPA-Personal & WPA-Enterprise

Wireless Architecture How to create profile for WPA-

Personal and WPA-Enterprise

WEP :Static Key Encryption

Static WEP Key

Static WEP Key

Probe Request-Response

Authentication RR , Association RR

Data Encrypted with Key

WPA :Non Static Key

Static WEP Key

Static WEP Key

Probe request response

Authentication , Association

Dynamic Key Generated First

Data Encrypted with Dynamic Key

How are dynamic keys Created ?

WPA / WPA2 PSK(Personal) Cracking

WPA Pre-shared Key

Passphrase (8-63 )

PBKDF2

Pre-Shared Key 256 bit

Passphrase (8-63 )

PBKDF2

Pre-Shared Key 256 bit

PBKDF2

• Password Based Key Derivation Function • RFC 2898 • PBKDF2 (Passphrase, SSID,ssidLen,4096,256 )• 4096 - Number of times the passphrase is

hashed • 256 - Intended Key Length of PSK

How does the Client know ?

• Beacon Frames ?• Probe Response Packets from the AP ? • Can be used to create a WPA/WPA2 Honeypot

as well!

How WEP Works

1) We try to collect large number of data packets

2) Bunch of large data packet contains weak IV 3) We Run it with the algorithm or aircrak-ng

and get the key

Then how to crack WPA-PSK ?

Lets “ Shake the hand” #4-way Handshake Probe Request Response

Authentication RR, Association RR Supplicant Authenticator

Pre-Shared Key 256 bit Pre-Shared Key 256 bit

Message 1

ANounce ANounce

PTK

SNounce

Message 2Snounce

PTK

Message 3

Key Installation Key Installed

Message 4Key Install Acknowledgement

+ MIC

Key Installed

Pairwise Transient Key

• PTK = Function (PTK ,ANounce, SNounce, Authenticator MAC ,Supplicant MAC )

PMK= Pre-Shared Key (Pairwise master Key) ANounce = Random by AP SNounce = Random by Client Authentication MAC = AP MAC Supplicant MAC = Client MAC MIC – Message Integrity Check ( Signature Algorithm )

WPA Working: Block Diagram

Passphrase (8-63 )

PBKDF2

Pre-Shared Key 256 bit

4 Way Handshake

SNonceAnonceAP MAC

Client MAC

PTK

WPA-PSK Susceptible to Dictionary Attack

WPA / WPA2 PSK(Personal) Cracking

DEMO

External Wireless Card

• Alfa Networks AWUS036H USB based card

• Already integrated with Backtrack and Kali

• Allows for packet sniffing • Allows for packet injection• We will use this in our

Demo session

Software Setup

• Run Kali Linux on VM machine • Connecting Alfa Adapter

Understanding Wireless Sniffing

• Wireless : Monitor mode • When you put card in monitor mode then it will

accept all the packet it is seeing in the current channel

• Inbuilt tool in Kali which helps in quickly put card into monitoring mode and sniff the packets

• Will use Tool name : airmon-ng to put card in to monitor mode ( part of aircrack sweet of tools )

Some Basic Terms

• MAC address or physical address is a unique identifier assigned to network interfaces for communications

• Access point >> Wireless router

• SSID (service set identifier) >> Network Name

• BSSID (basic service set identification ) >> MAC address of the access point

Using KaliLinux or BT

• Some Basic Backtrack Terms >>• Wlan0 – wireless interface• Mon0 – monitor mode• Handshake :-refers to the negotiation process between

the computer and a WiFi server using WPA encryption. Needed to crack WPA/WPA2.

• Dictionary - consisting the list of common passowords.• .cap file – used to store packets.

Tools Used

• Airmon-ng >> Placing different cards in monitor mode

Airodump-ng (Packet snniffer ) >> Tool used to listen to wireless routers in the area.

Aireplay-ng ( Packet injector ) >> Aireplay-ng is used to inject frames. – The primary function is to generate traffic for the

later use in aircrack-ng for cracking the WEP and WPA-PSK keys.

• Aircrack-ng >> Cracks WEP and WPA (Dictionary attack) keys.

Lets Hack

Lets Start

This will list all of the wireless cards that support monitor (not injection) mode.

The “(monitor mode enabled)” message means that the card has successfully been put into monitor mode. Note the name of the new monitor interface, mine is mon0.

• Airodump will now list all of the wireless networks in your area.

• airodump-ng –c [channel] –bssid [bssid] –w /root/Desktop/ [monitor interface]Replace [channel] with the channel of your target network. Paste the network BSSID where [bssid] is, and replace [monitor interface] with the name of your monitor-enabled interface, (mon0).

• Airodump with now monitor only the target network, allowing us to capture more specific information about it.

NOTE : • What we’re really doing now is

waiting for a device to connect or reconnect to the network, forcing the router to send out the four-way handshake that we need to capture in order to crack the password.

aireplay-ng –0 2 –a [router bssid] –c [client bssid] mon0

Upon hitting Enter, you’ll see aireplay-ng send the packets, and within moments, you should see this message appear on the airodump-ng screen!

Final Step

• aircrack-ng -a2 -b [router bssid] -w [path to wordlist] /root/Desktop/*.cap

• -a is the method aircrack will use to crack the handshake, 2=WPA method.-b stands for bssid, replace [router bssid] with the BSSID of the target router, mine is 00:14:BF:E0:E8:D5.-w stands for wordlist, replace [path to wordlist] with the path to a wordlist that you have downloaded. I have a wordlist called “wpa.txt” in the root folder./root/Desktop/*.cap is the path to the .cap file containing the password

If the phrase is in the wordlist, then aircrack-ng will show it too you like this

Thank you

Email: nilesh.s.sapariya@gmail.comTwitter : @nilesh_loganxContact : 8898813662