What Is a Zero-Day Vulnerability?

A zero-day vulnerability is a system or software vulnerability unknown to the vendor and for which no patch or means of mitigation are available at the time it is discovered. A zero-day attack occurs when threat actors develop and release malware that targets the zero-day vulnerability. By exploiting these security vulnerabilities, attackers can access critical systems and steal sensitive information.

Zero-day vulnerabilities pose a high risk to organizations because they are typically discovered before security researchers or software developers are aware of them and a patch can be released, allowing threat actors to exploit flaws and profit from their schemes.

How Zero-Day Attacks Work

A threat actor finds a system or software vulnerability, swiftly writes and implements an exploit code, and then deploys it to take advantage of a zero-day vulnerability. Threat actors often leverage social engineering attacks and exploit code to take advantage of vulnerable systems whenever a patch is unavailable for a zero-day vulnerability.

The combination of a vulnerability and targets' susceptibility to social engineering attacks explains why zero-day attacks are consistently very successful and present a significant security risk.

Examples of Zero-Day Attacks

Several well-known zero-day vulnerabilities have created significant problems.

Strontium, a Russian hacking syndicate, launched a spear-phishing campaign against the Democratic National Convention in 2016, sending spear-phishing emails that targeted Microsoft Windows and Adobe Flash vulnerabilities. These security flaws allowed attackers to install a backdoor through which they access a device's browser.

A zero-day vulnerability in Windows was discovered in January 2019, according to the Google virus-hunting team VirusTotal. This vulnerability allowed attackers to take advantage of how Windows authenticates file signatures. Via this vulnerability, attackers could slip a malicious file through Windows security by attaching it to a file already code-signed by Microsoft or Google.

Zero-Day Vulnerabilities vs. Zero-Day Exploits

Although both terms are used interchangeably, zero-day vulnerabilities occur when a flaw in software is unknown to the developer. Threat actors can develop a zero-day exploit if a patch is not released.

Zero-day exploits are usually disguised as malware or a bug; their deployment can be devastating for organizations until security measures are implemented to identify and block their progress.

Preventing Zero-Day Attacks

System developers and users are frequently unaware of zero-day vulnerabilities unless it is reported or discovered as a direct consequence of an attack. Traditional anti-malware solutions cannot always detect zero-day exploits, though solutions powered with cybersecurity AI can effectively block even never-before-seen zero-day attacks. Additional proactive best practices can prevent zero-day vulnerabilities from being exploited.

Routine Patch Management

Performing frequent scans of hardware and software assets is key to discovering newly released security patches. Because every endpoint is vulnerable to zero-day exploits, automating the patching cycle to coincide with publicly shared common vulnerability exposure (CVEs) or vendor-deployed fixes helps an organization prioritize responses to known and unknown vulnerabilities.

AI-Based Malware Detection

Traditional signature-based methods of combating zero-day threats have proven increasingly ineffective. Recognizing a threat, or waiting for notification from users, followed by developing a signature to recognize and counteract it, is too slow, leaving organizations vulnerable to attack. A solution leveraging Cybersecurity AI, though, can rapidly analyze millions of data sets to detect malware based on its behavior.

CylanceGUARD Prevents Zero-Day Attacks

Our Managed XDR solution CylanceGUARD^® is well equipped to mitigate the risks posed by zero-day vulnerabilities, and defends customers against exploitation of their systems. Our AI-driven approach to cybersecurity puts prevention first, neutralizing malware and increasing your cyber resilience.

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