what is Zero Day Attack

---Zero Day Attack<---

---------->can be harmful to specific computer long after a patch has been created and the vulnerability has been closed ,because many computer owners do not regularly update their software with patches made available by the software makers.But first because the typical zero day attack is unknown unit a large number of computer have been infected the option on anti-virus software to block currently unknown viruses and worms. A zero day attack will take advantage of that problem before a patch has been created. It is named zero day because it occurs before the first day the vulnerability is known.