MAC address filtering: Many networks use MAC address filtering as a basic security measure. This means only devices with pre-approved MAC addresses are allowed to connect. By spoofing the MAC address of a trusted device, an attacker can bypass this filter.
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A) To bypass network segmentation and access restricted network segments: While MAC spoofing might be a small part of a larger attack aimed at bypassing network segmentation, it's not the primary use case. Network segmentation relies more heavily on VLANs, firewalls, and routing rules, which are not directly affected by changing a MAC address.
C) To exploit weaknesses in wireless encryption protocols like WPA2: Exploiting WPA2 vulnerabilities is a separate attack vector. While a spoofed MAC address might be used in conjunction with a WPA2 attack (like capturing a handshake), the MAC spoofing itself doesn't directly exploit WPA2 weaknesses.
D) To disrupt the network by causing address conflicts with legitimate devices: This is possible, and it's called a MAC flooding or MAC spoofing attack for denial-of-service. However, the question asks for the primary reason, and impersonating a trusted device to gain unauthorized access is a more common and direct motive for simply changing one's MAC address.