5. Gaining Access - WEP Cracking

Basics

• WEP means: Wired Equvalent Privacy
• it'It's an old encryption
• usesUses an algorythm called RC4
• stillStill used in some networks
• canCan be cracked easily

How Encryption works

• eachEach Package is encrypted via a unique Keystream
• Random Initialization Vector (IV) is used to generate the Keystreams
• The IV is only 24 bits
• IV + (password) Key = keystream

WEP Cracking

IV is too small (24bits) IV is sent in plain text

Weakness

IV's will repeat on busy networks This will make WEP vulnerable to statistical attacks Repeated IV's can be used to determine the Keystream And break the encryption

Because the router already knows the (password) Key WLAN devices just need to send the IV