For several years many articles about computer, network, or Internet compromise mention the phrase “zero day exploit” or “zero day attack,” but rarely do these articles define what this is. A zero day exploit is any attack that was previously unknown to the target or security experts in general. Many believe that the term refers to attacks that were just released into the wild or developed by hackers in the current calendar day.
This is generally not the case. The “zero day” component of the term refers to the lack of prior knowledge about the attack. The main feature of a zero day attack is that since it’s an unknown attack, there are no specific defenses or filters for it. Thus, a wide number of targets are vulnerable to the exploit.
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