Zero Days

A zero-day (also known as a 0-day) is a computer software vulnerability that is unknown to, or unaddressed by, those who should be mitigating it. This means the vulnerability has been disclosed or discovered, but no official patch or fix is available from the vendor. The "zero" refers to the fact that the vendor has had zero days to address the flaw.

A zero-day exploit or attack occurs when attackers take advantage of a zero-day vulnerability to cause harm. This can include stealing data, installing malware, disrupting systems, or gaining unauthorized access. Because no patch exists, defending against zero-day exploits is particularly challenging, often requiring proactive security measures and vigilant monitoring.

The discovery of zero-day vulnerabilities can be made by security researchers, malicious actors, or even the software vendor themselves. Once discovered, the vulnerability information might be sold on the black market, used for targeted attacks, or reported to the vendor for patching. The time between discovery and the release of a patch is a critical window of opportunity for attackers.

The value of a zero-day vulnerability depends on several factors, including the affected software, the severity of the vulnerability, and the difficulty of exploiting it. Vulnerabilities in widely used software, such as operating systems and web browsers, are typically more valuable.

Common mitigations against zero-day attacks include:

• Intrusion Detection and Prevention Systems (IDS/IPS): These systems can detect and block malicious traffic that exploits zero-day vulnerabilities.
• Endpoint Detection and Response (EDR): EDR solutions provide visibility into endpoint activity and can detect and respond to suspicious behavior.
• Sandboxing: Running applications in a sandboxed environment can limit the impact of a zero-day exploit.
• Keeping software up to date: While not a defense against true zero-days (by definition), promptly patching vulnerabilities after they are addressed reduces overall attack surface.
• Least Privilege: Limiting user privileges reduces the potential damage an attacker can cause if they exploit a vulnerability.
• Network Segmentation: Isolating critical systems on separate network segments can limit the spread of an attack.