The Reality of Cyber Attacks: Why Known Vulnerabilities Are More Dangerous Than Zero-Day Exploits - Most Cyber Attacks Succeed Without Zero-Days

Cybersecurity discussions often highlight zero-day vulnerabilities as the biggest threat to organizations. These flaws, unknown to software makers and security teams, are seen as rare and powerful tools for attackers. Yet, data from 2024 and early 2025 reveals a different story. Most successful cyber attacks do not rely on zero-day exploits. Instead, attackers exploit known vulnerabilities, misconfigurations, and weak identity controls that organizations fail to fix promptly. Understanding this reality helps businesses focus their defenses where they matter most.

Why Zero-Day Vulnerabilities Get Too Much Attention

Zero-day vulnerabilities are exciting to the media and cybersecurity experts because they represent unknown risks. When attackers discover a zero-day flaw, they can exploit it before anyone knows it exists. This makes zero-days seem unstoppable and highly dangerous.

However, zero-day exploits are rare and expensive to develop. They require deep technical knowledge and resources. Because of this, attackers usually save zero-days for high-value targets or specific missions. For most cybercriminals, using zero-days is not practical or necessary.

The Real Threat Comes from Known Vulnerabilities

Most cyber attacks in 2024 and 2025 use vulnerabilities that have been publicly disclosed for months or even years. These known weaknesses exist in widely used software, operating systems, and network devices. Attackers scan for systems that have not applied security patches or updates and exploit these gaps.

For example, the Log4Shell vulnerability discovered in late 2021 affected millions of devices worldwide. Despite widespread awareness and available patches, many organizations still had unpatched systems in 2024. Attackers exploited these known flaws to gain access, steal data, or deploy ransomware.

Why Organizations Fail to Patch Known Vulnerabilities

• Complex IT environments: Many companies run hundreds or thousands of applications and devices. Keeping all of them updated is a massive challenge.

• Resource constraints: Smaller teams may lack the staff or budget to apply patches quickly.

• Fear of downtime: Some organizations delay updates fearing they will disrupt critical services.

• Lack of visibility: Without proper asset management, companies may not know which systems need patching.

  
  

These factors create a large attack surface that cybercriminals can exploit without needing zero-day exploits.

Misconfigurations and Weak Identity Controls Are Easy Targets

Besides unpatched software, attackers take advantage of misconfigurations and poor identity management. These issues are often overlooked but provide simple entry points.

Common Misconfigurations

• Open ports and services exposed to the internet without proper controls

• Default or weak passwords on devices and applications

• Excessive user permissions that allow attackers to move laterally after initial access

  
  

Weak Identity Controls

• Lack of multi-factor authentication (MFA)

• Poor password policies and reuse

• Inadequate monitoring of user activity

  
  

For instance, the 2023 MOVEit Transfer breach started with compromised credentials and weak identity controls. Attackers did not use zero-day exploits but leveraged stolen passwords and misconfigurations to access sensitive data.

How to Focus Cybersecurity Efforts Effectively

Knowing that zero-day exploits are not the main cause of breaches helps organizations prioritize their defenses. Here are practical steps to reduce risk from known vulnerabilities and misconfigurations:

• Implement a strong patch management process

Regularly scan for vulnerabilities and apply patches promptly. Automate updates where possible to reduce delays.

• Conduct regular configuration audits

Review network and system settings to close unnecessary open ports and disable unused services.

• Enforce strong identity and access controls

Use multi-factor authentication for all users, especially those with privileged access. Apply the principle of least privilege to limit permissions.

• Improve asset visibility

Maintain an up-to-date inventory of all hardware and software to ensure nothing is overlooked.

• Train employees on security best practices

Educate staff about phishing, password hygiene, and recognizing suspicious activity.

• Monitor and respond to threats quickly

Use security tools to detect unusual behavior and respond before attackers can cause damage.

Examples of Attacks Without Zero-Day Exploits

• Colonial Pipeline ransomware attack (2021)

Attackers used a compromised password to access the network. No zero-day exploit was involved.

• Equifax breach (2017)

Attackers exploited a known Apache Struts vulnerability that had a patch available months before the attack.

• SolarWinds supply chain attack (2020)

While sophisticated, this attack relied on compromised credentials and software supply chain weaknesses, not zero-day exploits.

These cases show that attackers often rely on basic security failures rather than advanced unknown vulnerabilities.

Final Thoughts on Cybersecurity Priorities

The focus on zero-day vulnerabilities can distract organizations from fixing the more common and preventable issues. Known vulnerabilities, misconfigurations, and weak identity controls cause most breaches. Addressing these areas reduces risk significantly and improves overall security posture.

Organizations should invest in patch management, configuration reviews, and strong identity controls. These steps provide a solid defense against the majority of cyber attacks seen today. By understanding where attackers really succeed, businesses can protect themselves more effectively and avoid costly breaches.