Definition - What does Zero-Day Malware mean?
Zero-day malware is a specific kind of malware or malicious software that has only recently been discovered. In general, a zero-day phenomenon is one that is not previously known about or anticipated. Security teams respond to zero-day malware and other zero-day events, tracking their ability to resolve them in real time.
Techopedia explains Zero-Day Malware
Zero-day malware can affect specific operating systems in specific ways. Some types of malware infiltrate a system attached to e-mails or otherwise disguised as harmless files. Others manipulate security protocols for wireless or IP networks. For example, many instances of zero-day malware affecting the Microsoft Internet Explorer browser have been addressed by Microsoft in the past. Many instances of zero-day malware are resolved with security upgrades or software patches.
In general, IT professionals will use the term zero-day malware to indicate that malware is brand new and that, as a result, teams may not have many resources with which to fight it. Over time, the developer and security communities build up these resources.
The term zero-day malware is a helpful marker to show that there is a new threat and that it needs to be documented and resolved as quickly as possible.