How to Prevent Zero-Day Attacks?

Zero day prevention has become a top priority for security teams worldwide, as these attacks bypass traditional defenses and cause devastating damage before patches become available.

Understanding how to prevent zero day attacks requires a multi-layered approach combining proactive security measures, continuous monitoring, and rapid response capabilities. Unlike conventional threats that security teams can prepare for, zero-day attacks exploit zero-day vulnerabilities that vendors haven’t yet discovered or patched, making zero day threat prevention one of the most challenging aspects of modern cybersecurity.

This guide examines proven strategies for defending against zero-day threats, from implementing robust security controls and employee training to leveraging threat intelligence and establishing effective incident response procedures.

How does a zero-day attack work? 

The discovery of a zero-day vulnerability often follows a sequence of events. Initially, a researcher, a malicious actor, or even a user may find a flaw. However, instead of immediately reporting the issue to the vendor for a patch, the discoverer might choose to exploit it or sell the information on the black market. This underground market for previously undisclosed bugs can be lucrative. These vulnerabilities fetch high prices due to their potency and the potential for covert exploitation.

Once a zero-day vulnerability is discovered, it can be weaponized through an exploit. An exploit is a piece of code or technique that takes advantage of a vulnerability to gain unauthorized access to a system, escalate privileges, bypass authentication, or execute malicious actions. Exploits can be deployed in various ways, including email attachments, malicious websites, or other vectors. They can target specific software or hardware versions, making it imperative for users to keep their systems up to date with patches and security updates.

Examples of zero-day attacks and exploits

Zero-day attacks have led to some of the most high-profile cybersecurity incidents in the last decade, including: 

1. Fortinet FortiOS vulnerability

In June 2023, Fortinet published an advisory about CVE-2023-27997, a critical vulnerability in FortiOS, the operating system for FortiGate firewalls and virtual private networks (VPNs).

SecurityScorecard’s threat intelligence team has provided guidance on how to identify vulnerable Fortinet devices within your organization and how to mitigate CVE-2023-27997.

2. MOVEit file transfer vulnerability

The 2023 vulnerability affecting MOVEit file transfer software was widespread, affecting multiple organizations around the world in government, energy, transportation, retail, communications, and professional services. This incident underscored the importance of securing file transfer systems and implementing comprehensive monitoring for unusual activity patterns.

3. Log4j remote code execution

The 2021 flaw related to Log4j enabled threat actors to remotely execute commands via remote code execution (RCE) on nearly any machine using Log4j. This zero-day attack affected millions of applications worldwide, demonstrating how widely used components can become attack vectors.

4. Chrome browser V8 engine

In 2021, Google’s Chrome browser suffered a series of zero-day threats. The vulnerability was caused by a bug in the V8 JavaScript engine used in the Chrome web browser. These vulnerabilities allowed attackers to execute arbitrary code within the browser context, highlighting the importance of keeping software applications updated and implementing browser security controls.

5. Zoom remote access vulnerability

This 2020 zero-day attack saw hackers access a user’s PC remotely if they were running an older version of Windows, take over their device, and gain access to all their files. The vulnerability specifically targeted older Windows versions, emphasizing the critical role of operating system updates in zero-day prevention strategies.

Consequences of zero-day exploits

One common type of exploit is the “drive-by download,” where a user unknowingly downloads malware by visiting a compromised website. The exploit code leverages the zero-day vulnerability to install malware on the user’s device, often without any visible signs of compromise. This stealthy approach allows attackers to infiltrate systems and establish a foothold for further malicious activities.

The consequences of previously unknown vulnerabilities and exploits can be severe. They can lead to data breaches, financial losses, reputational damage, and even endanger national security. A successful zero-day exploit can give unauthorized access to sensitive information, such as personal identities, financial records, or intellectual property. 

Furthermore, exploited systems can be used as launchpads for further attacks, amplifying the potential damage. This cascading effect demonstrates why comprehensive zero day threat prevention must address not only direct organizational risks but also third-party and vendor relationships.

How to respond to and prevent zero-day attacks

Cyberattacks on critical infrastructure have escalated significantly in recent years. Between January 2023 and January 2024, global critical infrastructure experienced over 420 million cyberattacks. This is equivalent to 13 attacks per second, a 30% increase from the previous year. In the energy and water sectors, median recovery costs from ransomware attacks have quadrupled to $3 million, highlighting the escalating financial impact.

Additionally, the number of high-severity vulnerabilities detected across publicly exposed digital footprints increased by 38% in 2024. With an average of 14 days for an exploit to be released into the wild following the detection of a vulnerability, precise prevention and response strategies are essential. This is especially true considering the average cost of a data breach, which increased significantly in recent years.

Having a solid team when responding to a zero-day threat is key. Once a zero-day vulnerability is found, the clock is already ticking, so you need to have the right people ready to detect, triage, and analyze what you’re dealing with. That’s why training your employees is critical, and so is knowing how to reach your vendors if the usual means of communication are down.

Government’s role in stopping zero-days

Governments and international organizations also play a vital role in addressing zero-day software bugs. They can establish regulations and frameworks that encourage responsible vulnerability disclosure and enforce penalties for those who exploit vulnerabilities for malicious purposes. 

Collaboration and information sharing between industry stakeholders, researchers, and government agencies are essential for a coordinated and effective response to the zero-day threat. 

How to prevent zero-day attacks and protect against zero-day threats

Being able to mitigate the risks associated with zero-day vulnerabilities and exploits requires a multifaceted approach. Vendors play a crucial role by implementing robust, secure coding practices, conducting regular security audits, and fostering a culture of responsible vulnerability disclosure. Encouraging researchers and ethical hackers to report vulnerabilities to vendors, instead of exploiting them or selling them on the black market, promotes a safer digital environment.

In addition to vendor efforts, end-users and organizations must prioritize cybersecurity hygiene. This includes keeping software up to date, employing security measures such as firewalls and antivirus software, and educating users about phishing and other common attack vectors. Regular training and awareness programs can significantly reduce the likelihood of falling victim to exploits.

Furthermore, fostering a cybersecurity community that actively engages in proactive defense measures, such as vulnerability research and threat intelligence sharing, can aid in the early detection and mitigation of zero-day vulnerabilities. Security researchers and organizations need platforms to collaborate, share insights, and collectively work towards enhancing the overall security posture of not just their own environments but that of their third- and fourth-party vendors as well.

Key zero-day prevention strategies

Step 1: Build Your Foundation: Create comprehensive asset inventories covering all systems, software, and devices. Implement defense in depth with multiple security layers for redundancy when primary defenses fail.

Step 2: Deploy Advanced Detection: Install behavioral analytics and threat detection systems to identify anomaly patterns indicating zero-day activity. Set up endpoint detection to monitor suspicious behavior that traditional antivirus misses.

Step 3: Secure Your Network: Implement network segmentation to limit attack spread through strategic isolation, preventing lateral movement. Deploy a zero-trust architecture to verify every user and device accessing network resources.

Step 4: Manage Third-Party Risks: Continuously monitor vendor security postures, as supply chain attacks often leverage vulnerabilities in partner organizations. Create and test incident response plans for rapid threat containment.

Step 5: Train and Stay Informed Provide security awareness training to help employees recognize emerging threats before exploitation. Leverage threat intelligence to keep teams informed about new vulnerabilities and attack patterns.

Step 6: Test and Validate: Conduct regular penetration testing to identify attack vectors before malicious exploitation, strengthening zero day threat prevention across digital ecosystems.

Conclusion

Zero-day attack prevention isn’t about perfect security. It’s about building resilient systems that can detect, contain, and recover from threats quickly. The strategies above represent proven approaches to significantly improve your defensive posture against these invisible threats.

But what happens when prevention isn’t enough? The most forward-thinking security teams supplement these foundational strategies with predictive intelligence that identifies zero-day threats before they strike.

SecurityScorecard provides continuous monitoring of your entire digital ecosystem, including third-party vendors, with real-time security ratings. Our Zero-Day-as-a-Service (ZDaaS) takes this protection further with early warning detection for newly discovered vulnerabilities across your supply chain.

Get your free security rating today, or explore our ZDaaS service for predictive threat intelligence that protects your entire vendor ecosystem.