Which of the following attacks allows the bypassing of access control lists on servers or routers, and helps an attacker to hide? Each correct answer represents a complete solution. Choose two.

IP spoofing involves forging the source IP address in a packet header. This allows an attacker's traffic to appear as if it originates from a trusted, internal source, thereby bypassing IP-based Access Control Lists (ACLs) on routers and firewalls. Similarly, MAC spoofing alters the Media Access Control (MAC) address of a network interface to impersonate a legitimate, authorized device. This is effective against security mechanisms like MAC filtering on switches and wireless access points. Both techniques inherently obfuscate the attacker's true origin, making it difficult to trace the malicious activity back to its source.

A. DNS cache poisoning: This attack redirects users to a malicious site by corrupting DNS records; it does not directly bypass ACLs on a target server or router.
D. DDoS attack: The primary goal of a Distributed Denial-of-Service (DDoS) attack is to overwhelm a target with traffic to make it unavailable, not to bypass access controls.

1. For IP Spoofing: Kaur, J., & Singh, A. (2015). A Survey of IP Spoofing Attacks and Their Countermeasures. Proceedings of the 2015 2nd International Conference on Computing for Sustainable Global Development (INDIACom), 170-175. Section II.A states, "IP spoofing is a technique used to gain unauthorized access to computers, where intruder sends messages to a computer with an IP address indicating that the message is coming from a trusted host." This directly supports bypassing access controls (unauthorized access) and hiding (impersonating a trusted host). (Available via IEEE Xplore).

2. For MAC Spoofing: Tanenbaum, A. S., & Wetherall, D. J. (2011). Computer Networks (5th ed.). Pearson Education. In Chapter 8, "Network Security," the text discusses how authentication can be based on source addresses (like MAC addresses for 802.11). It explains that an intruder can "spoof" the MAC address of an authorized station to bypass this access control. (Refer to Section 8.4.3, "IEEE 802.11 Security").

3. For General Concepts: Purdue University, CS 526: Information Security course materials. Lecture notes on "Network Security" describe how IP spoofing is used to circumvent authentication mechanisms that are based on IP addresses, which are a form of access control. The notes also cover how MAC spoofing bypasses MAC address filtering. (Specific lecture slides on Network Security and Firewalls).