Zero-day

Zero-day, also spelled 0-day, is a computer security term used to describe a vulnerability or exploit which is known to the public but has not yet been patched or otherwise mitigated. It is an exploit which can be used by hackers to gain access to sensitive data, or control of vulnerable systems, prior to the development of a fix by the vendor or the public recognition of the exploit.

Zero-day attacks are considered very dangerous both for their potential to cause wide-scale security breaches as well as because they are difficult to detect and prevent. As soon as an attacker discovers a zero-day vulnerability, he or she can use it to launch a successful attack without detection before a patch has been created and applied. Such attacks have become increasingly common, and as a result a large number of techniques for discovering and responding to zero-day problems have been developed.

The term zero-day was first used in the late 1990s, although the concept behind it has existed since the dawn of computing. Security researchers have developed sophisticated methods to detect and react to zero-day threats, such as honeypots, fuzzing, and code rewriting. A wide range of mitigation technologies are available, such as antivirus, firewalls, intrusion prevention systems, patch scanning, trusted computing, and virtualization.

With the increase of internet usage, the number of zero-day threats has also grown; therefore, protecting against them has become an essential part of cybersecurity, with companies taking proactive measures to stay safe from these attacks.