Comprehensive and Detailed Explanation From Exact Extract:
A Zero-day vulnerability refers to a security flaw in software or hardware that is unknown to the vendor or has not yet been patched. If this vulnerability is exploited before the vendor has issued a fix or patch, it becomes a Zero-day exploit. These attacks are highly dangerous because they take advantage of the absence of defenses due to the lack of awareness or mitigation options.
A. Spoofing is a form of impersonation, not necessarily tied to unpatched vulnerabilities.
B. Brute-force attacks rely on repeatedly guessing credentials and are not related to software flaws.
C. DoS (Denial of Service) attacks are meant to overwhelm systems and don't necessarily exploit unknown vulnerabilities.
[Reference:, CompTIA A+ 220-1102 Objective 2.3: Compare and contrast common social engineering, threats, and vulnerabilities., Study Guide Section: Threat types — Zero-day attacks, definitions, and implications, , , ]
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