Zero-Day (0-day)

Zero-Day (0-day) is a vulnerability in software that is unknown to its developers or vendor. The name comes from the fact that the developer had "zero days" to fix the vulnerability before it was discovered.

Why It's Dangerous

• No official patch available
• Antivirus doesn't detect
• Can be used in targeted attacks
• High value on black market

Types of Zero-Day

• Zero-Day Vulnerability — the vulnerability itself
• Zero-Day Exploit — code to exploit it
• Zero-Day Attack — attack using the exploit

Protection

• Defense in Depth
• Behavior-based detection
• Sandboxing
• Regular patching
• Network segmentation