CompTIA Security Plus Mock Test Q511

An administrator notices an unusual spike in network traffic from many sources. The administrator suspects that:

A. it is being caused by the presence of a rogue access point.
B. it is the beginning of a DDoS attack.
C. the IDS has been compromised.
D. the internal DNS tables have been poisoned.

Correct Answer: B
Section: Threats and Vulnerabilities

Explanation:
A Distributed Denial of Service (DDoS) attack is an attack from several different computers targeting a single computer. One common method of attack involves saturating the target machine with external communications requests, so much so that it cannot respond to legitimate traffic, or responds so slowly as to be rendered essentially unavailable. Such attacks usually lead to a server overload. A distributed denial-of-service (DDoS) attack occurs when multiple systems flood the bandwidth or resources of a targeted system, usually one or more web servers. Such an attack is often the result of multiple compromised systems (for example a botnet) flooding the targeted system with traffic. When a server is overloaded with connections, new connections can no longer be accepted. The major advantages to an attacker of using a distributed denial-of-service attack are that multiple machines can generate more attack traffic than one machine, multiple attack machines are harder to turn off than one attack machine, and that the behavior of each attack machine can be stealthier, making it harder to track and shut down. These attacker advantages cause challenges for defense mechanisms. For example, merely purchasing more incoming bandwidth than the current volume of the attack might not help, because the attacker might be able to simply add more attack machines. This after all will end up completely crashing a website for periods of time. Malware can carry DDoS attack mechanisms; one of the better-known examples of this was MyDoom. Its DoS mechanism was triggered on a specific date and time. This type of DDoS involved hardcoding the target IP address prior to release of the malware and no further interaction was necessary to launch the attack.

Incorrect Answers:
A: A rogue access point would not cause a spike in network traffic from many sources unless many computers had connected to the rogue access point and started sending lots of traffic.
C: The question states that an administrator notices an unusual spike in network traffic from many sources. You would typically notice this on a firewall or an IDS system. It’s unlikely the IDS has been compromised. A DDoS attack is far more common.
D: DNS poisoning is the process of inserting incorrect information into DNS records. This may cause a slight increase in broadcast traffic on the network (as computers try to locate each other) but it would not cause a serious spike in network traffic.

References:
http://en.wikipedia.org/wiki/Denial-of-service_attack