SYN Flood is a DOS attack in which an attacker deliberately violates the three-way handshake and opens a large number of half-open TCP connections.The signature for SYN Flood attack is:
Answer(s): C
A SYN attack occurs when an attacker exploits the use of the buffer space during a Transmission Control Protocol (TCP) session initialization handshake. The attacker floods the target system's small "in-process" queue with connection requests, but it does not respond when a target system replies to those requests. This causes the target system to time out while waiting for the proper response, which makes the system crash or become unusable.
Henry is an attacker and wants to gain control of a system and use it to flood a target system with requests, so as to prevent legitimate users from gaining access. What type of attack is Henry using?
Answer(s): B
Henry’s intention is to perform a DoS attack against his target, possibly a DDoS attack. He uses systems other than his own to perform the attack in order to cover the tracks back to him and to get more “punch” in the DoS attack if he uses multiple systems.
Eve decides to get her hands dirty and tries out a Denial of Service attack that is relatively new to her. This time she envisages using a different kind of method to attack Brownies Inc. Eve tries to forge the packets and uses the broadcast address. She launches an attack similar to that of fraggle. What is the technique that Eve used in the case above?
Answer(s): A
A fraggle attack is a variation of the smurf attack for denial of service in which the attacker sends spoofed UDP packets instead of ICMP echo reply (ping) packets to the broadcast address of a large network.
Peter is a Network Admin. He is concerned that his network is vulnerable to a smurf attack. What should Peter do to prevent a smurf attack? Select the best answer.
Answer(s): E
Unicasts are one-to-one IP transmissions, by disabling this he would disable most network transmissions but still not prevent the smurf attack. Turning of multicast or fragmentation on the router has nothing to do with Peter’s concerns as a smurf attack uses broadcast, not multicast and has nothing to do with fragmentation. Anti-virus protection will not help prevent a smurf attack. A smurf attack is a broadcast from a spoofed source. If directed broadcasts are enabled on the destination all the computers at the destination will respond to the spoofed source, which is really the victim. Disabling directed broadcasts on a router can prevent the attack.
Peter has been monitoring his IDS and sees that there are a huge number of ICMP Echo Reply packets that are being received on the External Gateway interface. Further inspection reveals they are not responses from internal hosts request but simply responses coming from the Internet. What could be the likely cause of this?
An attacker sends forged ICMP echo packets to broadcast addresses of vulnerable networks with forged source address pointing to the target (victim) of the attack. All the systems on these networks reply to the victim with ICMP echo replies. This rapidly exhausts the bandwidth available to the target.
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