A zero day in cybersecurity refers to a security vulnerability in software, hardware, or firmware that is unknown to the vendor or anyone capable of mitigating it. The term “zero day” highlights that the developers have had zero days to address or patch the flaw because it has just been discovered—often by malicious actors—before any fix or defensive measures are available.
Key Concepts
• Zero-Day Vulnerability:
An undiscovered or unaddressed security flaw in a system that is not yet known to the vendor or the public. Because there is no patch or fix, systems remain exposed and vulnerable to attack.
• Zero-Day Exploit:
The method or technique used by an attacker to take advantage of a zero-day vulnerability. This could involve malware, code injection, or other tactics to gain unauthorized access or cause harm.
• Zero-Day Attack:
An attack that occurs when a threat actor uses a zero-day exploit to compromise a system before the vendor has had a chance to develop and release a patch. These attacks are particularly dangerous because traditional security defenses are not prepared for them.
Why Are Zero Days Dangerous?
Zero-day vulnerabilities are especially threatening because:
• There is no available fix or patch at the time of discovery.
• Attackers can exploit the vulnerability before anyone is aware of it, leaving users and organizations defenseless.
• Detection is difficult, as signature-based security tools cannot recognize the new threat.
Notable Examples
• The Stuxnet worm (2010) used multiple zero-day vulnerabilities to sabotage Iran’s nuclear program, demonstrating the significant impact such exploits can have.
• The Zoom vulnerability (2020) allowed attackers to gain remote access to users’ computers before a patch was released, affecting millions of users during the rise of remote work.