What is the most common kind of no day malware?

Zero day malware is a type of malware that is not yet understood to the anti-virus software.  https://catbitcoin.com/?p=1494 The most typical type of no day malware is a trojan horse.  https://cleardex.io/?p=849 A trojan horse is a type of malware that disguises itself as a safe program in order to gain access to a system.