(ISC)2 Certified in Cybersecurity Practice Exam

What is a “Zero Day” vulnerability?

1. A vulnerability that is widely known

2. A previously unknown vulnerability that can be exploited

3. A vulnerability that has been patched

4. A common security procedure

The correct answer is: A previously unknown vulnerability that can be exploited

A “Zero Day” vulnerability refers to a previously unknown vulnerability that can be exploited by attackers before any patches or defenses can be developed. The term "zero-day" indicates that the developers or the security team had zero days to address the vulnerability because they were unaware of its existence when it was discovered. This lack of awareness and timing creates a critical security risk, as it allows attackers to exploit the vulnerability without fear of detection or remediation. When a zero-day vulnerability is discovered, the urgency to create a fix increases significantly because it exposes systems to potential attacks without prior notice. Understanding this concept is crucial for cybersecurity professionals, as it underscores the importance of proactive security measures and staying informed about emerging threats to safeguard systems effectively.