Zero day attack
A zero-day (or zero-hour or day zero) attack is a computer threat that attempts to manipulate the computer application vulnerabilities that are undisclosed to the software developer. Zero-day exploits is the actual code that can use a security hole to carry out an attack. These exploits are used or shared by attackers before the software developer knows about the vulnerability.
Zero day
The zero day or day zero is the day a new vulnerability is made known. In some cases, a zero day exploit is referred to as an exploit for which no patch is available yet. Day one is a day at which the patch is made available.
Zombies
A zombie computer is a computer connected to the internet that has been compromised by a hacker, a computer virus, or a trojan horse. Generally, a compromised machine is only one of many in a botnet, and is used to perform malicious tasks of one sort or another under remote direction.