Network Attacks

Question 1

How does a TCP Reset Attack work?

Answer 1

By sending a RST packet to immediately break the connection

Question 2

How does a TCP Flooding Attack work?

Answer 2

By sending continuously sending packets that do not finish the 3rd step of the TCP handshake (sending acknowledgment packet)

Question 3

What is a countermeasure to the SYN flooding attack

Answer 3

SYN Cookies

Question 4

How do SYN cookies work?

Answer 4

They do not store half open connections in queue.
This is done by asking for a hashed sequence number that can be decrypted using only a secret key from the server.
This value is H.
H will be sent as initial sequence number from the server.
H will not reach the attacker as the attacker must create half open connections to random IPs.

Question 5

What is the goal of the TCP session hijacking attack?

Answer 5

To inject data in a TCP connection, triggering buffer overflow at the receivers machine

Question 6

What is the requirement for the TCP session hijacking attack in terms of the sequence number?

Answer 6

It must inject data at the next sequence number.
If a packet uses x + theta, then the injected data will be stored theta spaces later, having no effect.
Furthermore, if theta is too large, it may fall out of the boundary

Question 7

What countermeasures exist to make it difficult for attackers to spoof packets

Answer 7

Randomise initial sequence number.
Encrypt TCP payload and header.