Wireless LAN Security potx

Introduction WLAN Security Threats Evolution of Wireless LAN Security y Demo : Crack WEP, WPA PSK Prevention Q&A... Wireless LAN Security Threats... Evolution of Wireless LAN Security...

Wireless LAN Security

Hồ Đắc Biên bien.ho@ttgtc.com

0985 196 884 MCSA, MCITP-EA, CCNP, , , , CCIE Written, Security+, CEH

Introduction WLAN Security Threats Evolution of Wireless LAN Security y Demo : Crack WEP, WPA PSK

Prevention Q&A

Introduction WLAN Security Threats

Introduction

Wireless LAN Security Threats

Toys for Hackers

A Dual-Use Product

Netstumbler

Kismet

Sniffer on WLAN

• All messages are sent in clear over the wireless network.

• Eavesdroppers may be stealing your messages secretly…

eavesdropper

gateway.cstelnet gateway.cs

Evolution of Wireless LAN Security

Evolution of Wireless LAN Security

ƒ User

ƒ Standardized

ƒ Improved encryption

ƒ Strong user

ƒ AES strong encryption

ƒ 802.1X EAP (LEAP, PEAP)

ƒ Strong, user authentication (such as, LEAP, PEAP, EAP-FAST)

ƒ Dynamic key management

WEP (Wired Equivalent Privacy)

WEP (Wired Equivalent Privacy)

Uses either 40 bit or 104 bit shared ke

Uses either 40-bit or 104-bit shared-key encryption with a 24-bit initialization vector This encryption scheme is extremely vulnerable yp y

1 WEP keys are static

2 Initialization vector is short and possibly

constant

3 Initialization vector easily known to attacker

4 WEP has no cryptographic integrity protection

4 WEP has no cryptographic integrity protection

WEP (Continued)

RC4 Developed by Ron Rivest Became public in 1994

Stream cipher used for WEP Ideal for its extremely fast speed for generating pseudo random numbers

WEP(Diagram)

Encryption Standards(Continued)

WPA

128 bit ti ith 48 bit i iti li ti t 128-bit encryption with a 48-bit initialization vector Uses TKIP

Extends the IV space

Cracks in WEP – Historic Evolution

2001 - The insecurity of 802.11, Mobicom, July 2001

N Borisov, I Goldberg and D Wagner.

2001 - Weaknesses in the key scheduling algorithm of RC4.

S Fluhrer, I Mantin, A Shamir Aug 2001.

2002 U i th Fl h M ti d Sh i Att k t B k WEP

2002 - Using the Fluhrer, Mantin, and Shamir Attack to Break WEP

A Stubblefield, J Ioannidis, A Rubin.

2004 – KoreK, improves on the above technique and reduces the

l it f WEP ki W i l d complexity of WEP cracking We now require only around 500,000 packets to break the WEP key.

2005 Adreas Klein introduces more correlations between the

2005 – Adreas Klein introduces more correlations between the RC4 key stream and the key.

2007 – PTW extend Andreas technique to further simplify WEP Cracking Now with just around 60 000 – 90 000 packets it is

Cracking Now with just around 60,000 90,000 packets it is possible to break the WEP key.

WEP Attacks – exposure area

Using known methods, exposure is

limited to RF range of WEP enabled

No Mutual Authentication

p

Message Modification

Message Injection

1 10 100 1000 On the Moon

Demo : Crack WEP Key, WPA PSK

Wireless network model

2 A user computer connects to p

router through wireless

connection which is protected

by WEP

3 Attacker doesn’t know the WEP

password and even the SSID

password and even the SSID

and Channel.

Crack WEP Key

1 Wireless card support crack WEP key pp y

Wireless Card Crack WEP

TL-WN510G WG511T

WG111T D-Link WUA-1340 WG111T

Setup Card & Begin Scan

First, you need to scan for a victim & setup your

card For atheros, Kismet automatically detects, others you will need to edit Kismet’s config.

Once you know the bssid & channel you need,

Once you know the bssid & channel you need, set your network card to Monitor

Begin Dumping & Injecting

Use airodump to record all of the IVs you’ll need

to crack Use aireplay to inject a mass quantity to get new IVs to use to crack the key.

You’ll need at least 100,000 keys to crack a bit WEP key, generally 200-300k is good

128-Use new PTW attack we only need 20,000 for 64 bits, 60,000 – 80,000 for 128 bits WEP

Demo: Airodump

1 Select adapter 2.Choose interface

*

*Airodump Airodump supports limited supports limited kind of wireless adapters including:

including: Atheros Atheros Aironet Aironet, ,

Realteak Realteak, , PrismGT PrismGT and Intel and Intel 3956.

Aircrack-ng

Crack WPA PSK

aircrack-ng -w (dictionary file) (file name of cap created by airdump)

Prevention

Security on Open Networks y p

Use a personal firewall or similar protection

Use an intrusion protection system (IPS)

Scan for viruses

Keep systems religiously up to date

Keep systems religiously up to date

Website : http://ttgtc.com Forum : http://ttgtc.com/forum

Securing WEP

Use WEP only if nothing else better is available y g

Use 128 bit encryption

Test all access points for weak packets (Kismet)

Consider changing shared access keys periodically or

when security situation changes

Use with MAC controls on small networks

Keep access points behind a firewall in a DMZ

Assume the network is untrusted and provide for

Assume the network is untrusted and provide for

additional security

Securing WPA/WPA2

Use WPA2 or WPA when ever available

Use hardened authentication where possible

Radius EAP / LEAP

Use strong passwords for WPA Pre-Shared Keys

Minimum of 17 characters Include complex characters (numbers, caps, punc) It's easier to break weak passwords on WPA PSK than it is to do codebook attacks on WEP!

Resources and References

http://www.informationheadquarters.com/Internet/WIFI.shtml http://www.networkintrusion.co.uk/wireless.htm

htt // b ifi t / http://www.usbwifi.orcon.net.nz/

Q & A

Email : bien.ho@ttgtc.com You can download this slide at TTG forum

http://ttgtc.com/forum/

Website : http://ttgtc.com Forum : http://ttgtc.com/forum