No day malware, also called absolutely no hour malware or no day attacks, is a kind of malware that takes benefit of a previously unidentified software vulnerability. https://scarabnet.org/?p=501https://zerogov.net/?p=830 Attackers who have the ability to exploit these vulnerabilities can acquire access to a system or network with no detection. This makes zero day malware a severe hazard to services and individuals alike.
Traditional malware, on the other hand, is malware that is popular and has actually been around for a long time. Although conventional malware can still be dangerous, it is not as difficult or stealthy to discover as zero day malware.