Definition - What does Zero-Day Exploit mean?
A zero-day exploit involves targeting specific computer vulnerabilities in tandem with a general announcement that identifies the explicit security vulnerability within a software program. When software vulnerability is identified, information about its nature is relayed to a specific person or software company and a secure remedy is urgently implemented. It is during this precious time period that an attack may occur should the vulnerability be announced to the entire public. The time involved it takes to combat the problem may be longer than it takes to spread the word about it, providing a tip to hackers who may be on the lookout for this type of opportunity.
Techopedia explains Zero-Day Exploit
Once a computer vulnerability is exposed to the general public, there is a very real danger that malicious parties will exploit the vulnerability before it can be repaired. In other instances, the hacker may be the very first to discover the vulnerability and may announce it to the general public. In this case, the software company or individual may not be notified in time to fix the vulnerability, giving hackers just enough time to exploit it. To guard against this type of exploitation, companies can enlist various protection measures including network access controls, lockdowns of wireless access entries, virtual local area networks and intrusion detection systems.