Hacking Wireless Networks

Question 1

Orthogonal frequency-division multiplexing (OFDM)

Answer 1

Orthogonal frequency-division multiplexing is a method of data transmission where a single information stream is split among several closely spaced narrowband subchannel frequencies instead of a single Wideband channel frequency. It is mostly used in wireless data transmission

Question 2

Direct sequence spread spectrum (DSSS)

Answer 2

Direct sequence spread spectrum (DSSS) is a transmission technology used in local area wireless network transmissions. In this technology, a data signal at the sending station is combined with a high data rate bit sequence, which divides user data based on a spreading ratio.

Question 3

Fluhrer, Mantin and Shamir (FMS) Attack

Answer 3

A Fluhrer, Mantin and Shamir (FMS) Attack exposes a weakness in RC4 Key Scheduling Algorithm to recover the key from encrypted messages

Question 4

Issues of WEP

Answer 4

• IV is part of RC4 Encryption
• IV sent in plaintext
• First bytes of keystream are strongly non-random
• Static Key
• Weak Integrity Check Value

Question 5

Steps of WEP

Answer 5

1. Combine plaintext with CRC
2. Initialization Vector and Secret key through RC4 to generate keystream
3. XOR plaintext+CRC with Keystream to generate ciphertext
4. Prepend Initialization Vector to ciphertext

Question 6

ARP Request Replay Attack

Answer 6

Program listens for an ARP Packet and retransmits it back to AP

AP returns packet with new IV

And as the AP continually returns the new IV’s the program can then determine (crack) the WEP Key