Viruses and malware are designed to exploit inadvertent vulnerabilities in software applications. Often, a vulnerability is found, and the race is on to develop a patch to fix it, while criminals rush to develop a virus or malware to exploit it. Vulnerabilities can be found in software ranging from Windows OS versions to business applications like Word, Excel, and PowerPoint, email applications, mobile OS versions, line-of-business applications such as accounting software, EMR/EHR systems, and the list goes on and on. In recent years, the targets have shifted: in 2025, nearly half of all exploited zero-days targeted enterprise-grade technology like firewalls, VPNs, and other internet-facing “edge” devices — an all-time high — while operating systems remained the most targeted category.[1]
A zero-day vulnerability is a software security flaw that attackers exploit before the vendor has a patch available — often before the vendor even knows the flaw exists. The “zero day” refers to the zero days of warning defenders have to develop a fix. These vulnerabilities can be exploited by cyber criminals to compromise computer systems. When hackers are able to take advantage of a zero-day vulnerability that doesn’t have a patch available, that’s called a zero-day attack. And these attacks are accelerating: Google’s Threat Intelligence Group tracked 90 zero-day vulnerabilities exploited in the wild in 2025, up from 78 the year before.[2] Worse, nearly a third of the vulnerabilities exploited last year were attacked on, or before the very day they were publicly disclosed — leaving defenders little to no time to react.[3]
How can you protect your business from zero-day attacks?
Zero-day vulnerabilities pose a serious security risk to your business. In the case of a zero-day attack, there obviously isn’t a patch available to fix the security flaw — and as 2025 made clear, detection and patching alone can’t keep up when a flaw is weaponized before any fix exists. So, what can you do? The best defense is to have proactive and reactive security measures in place.
Proactive security measures include a strong intrusion defense or firewall with a comprehensive security gateway layered on for added protection. Add to that a next-generation anti-virus application that can identify attacks by their behavior, not their signature. Artificial Intelligence-based endpoint protection or antivirus provides protection against even unknown risks, such as zero-day attacks. Having advanced email security helps protect the #1 delivery vehicle for most viruses and malware: your email. Because so many of today’s attacks hit internet-facing equipment, it’s just as important to keep firewalls, VPNs, and other edge devices patched, hardened, and actively monitored. Lastly, you want to have a business class Business Continuity and Disaster Recovery (BCDR) Backup solution in place to ensure your business can be back up and running in a matter of minutes should you be hit with a zero-day attack. Most importantly, you should also be constantly training your employees so they become an added layer of defense rather than your greatest weakness against cyber-attacks.
On the reactive side, you need to make sure that patches are installed as soon as they become available — speed matters more than ever now that many flaws are exploited within 24 hours of disclosure.[4] You should have your systems actively monitored so issues can be addressed quickly before they get out of hand. And you should have IT professionals available to assist in mitigation and recovery should you become the victim of an attack.
You may not be able to completely stop every cyber-attack, especially as attackers begin using AI to discover flaws and build exploits faster than ever[5], but having a well-defined plan of defense can ensure that attacks don’t put you out of business.
To learn how to protect your business from today's evolving security threats, look to IT professionals who understand cybersecurity and have the tools and know-how to help keep your business secure.
[1] Google Threat Intelligence Group 2025 report, via Cybersecurity Dive, March 2026.
[2] Google Threat Intelligence Group, “2025 Zero-Days in Review,” March 2026.
[3] VulnCheck exploitation data, as reported by CSO Online, “Zero-day exploits hit enterprises faster and harder,” March 2026.
[4] VulnCheck, 2025 known-exploited-vulnerability data.
[5] Casey Charrier, Google Threat Intelligence Group, via Cybersecurity Dive, March 2026.
