Zero day malware is malware that is not yet understood to anti-virus software vendors or companies. It makes use of vulnerabilities in software or hardware that have not yet been covered or fixed. The term "no day" comes from the reality that once the malware is discovered, there is zero time to patch the vulnerabilities before enemies can exploit them.
Zero day malware is typically utilized in targeted attacks versus specific organizations or individuals. The assaulters will carefully select their targets, and after that craft their malware to particularly make use of the vulnerabilities in those target's systems. This makes no day malware really difficult to protect and detect versus.
https://cleardex.io/?p=731 Among the most well-known examples of zero day malware is the Stuxnet worm, which was utilized to attack commercial control systems. Stuxnet was able to spread itself through USB drives and infected networks of computers, without being identified by anti-virus software application. https://tourismcrisis.org/?p=355 It then particularly targeted Siemens commercial control systems, and caused physical damage to centrifuges in Iran.
Absolutely no day malware is a serious risk to individuals and companies. It is essential to keep your systems up-to-date with the current security patches, and to be knowledgeable about the current hazards.