What is Zero Day Virus?
A zero-day virus is malicious software that is not documented before a specific day. When the virus is officially detected and identified by an organization in the anti-virus community, it becomes a zero-day virus. Professionals use zero day as a yardstick for responding to a computer virus.
A zero-day virus has a particular application in the antivirus industry. Antivirus software manufacturers operate on certain key principles, including the need to protect their customers from the greatest possible number of viruses and to limit and mitigate cyberattacks. This is a very competitive metric within the industry, as business / government customers and private individuals seek the best virus protection for their networks.
One problem with a zero-day virus is that it doesn't have a signature because it wasn't previously documented. Signatures involve verifying the method and coding of a virus in order to anticipate and protect systems from the virus. One method to work against zero-day viruses is the heuristic anti-virus method, which uses experience-based analysis to examine other factors in addition to a signature for a virus to determine what a system needs to protect against a virus.