The Silent Threat: Why Unpatched Software is an Attacker's Best Friend

In cybersecurity, we talk a lot about sophisticated attacks, zero-day exploits, and advanced persistent threats. But what if one of the biggest risks to your business isn't a complex new attack, but something far more common and preventable? The simple truth is that unpatched and outdated software is a leading cause of major data breaches.

Even a single unpatched vulnerability can become an open door for an attacker. It's a risk that's often overlooked, but the consequences can be catastrophic. Let's explore why this vulnerability is so dangerous and, more importantly, how you can fix it.

The Problem: A Known Exploited Vulnerability (KEV)

When a vendor discovers a security flaw, they release a patch or an update to fix it. This is a crucial step in the software lifecycle. They also submit it to MITRE who assigns it a Common Vulnerabilities Exposure (CVE) number. However, this means when a patch is released, the vulnerability itself becomes public knowledge. This creates a critical window of opportunity for hackers.

The Cybersecurity and Infrastructure Security Agency (CISA) maintains the KEV Catalog, the authoritative source for all vulnerabilities being actively exploited in the wild. Attackers can then use automated scanning tools to scour the Internet for systems that contain KEVs.  For an attacker, it's the digital equivalent of having a master key to unlock any door. The work is already done; all they have to do is walk in.

These vulnerabilities often allow for Remote Code Execution (RCE). This means an attacker can run commands on your system from a remote location, giving them full control. They can install malware, steal data, or use your system as a launchpad for further attacks on yours or others’ networks.

Real-World Example

The WannaCry ransomware attack of 2017 is a perfect case study. It exploited a known vulnerability in older versions of the Windows operating system for which Microsoft had already released a patch. The attack infected over 200,000 computers in 150 countries, causing billions of dollars in damage, simply because organizations failed to apply a readily available security update. This massive cyberattack could have been largely prevented with proper patching. SOURCE

The Solution: Building a Proactive Patch Management Strategy

Ignoring software updates is not an option. A robust and consistent patch management strategy is your strongest defense against these attacks.

1. Implement Automation Where Possible

Manually checking for updates is time-consuming and prone to human error. Use patch management software or built-in automation features to automatically scan, download, and install updates for all your operating systems and third-party applications. This ensures you're protected as soon as possible after a patch is released.

2. Prioritize Critical Patches

Not all patches are created equal. You may be tempted to patch the most critical vulnerabilities first, but this will likely prove impractical. It depends on the criticality of the system it’s on as well. For example, if you find a level 10 severity vulnerability on a system that is not Internet-facing and stores non-sensitive data, but you discover a level 7 severity vulnerability on a public-facing server that processes credit card transactions. With your limited time and effort, which do you patch first?

This is where the Stakeholder-Specific Vulnerability Categorization (SSVC) model provides a vulnerability analysis methodology that accounts for a vulnerability's exploitation status, impacts to safety, and prevalence of the affected product in a singular system, and uses the KEV catalog to assess the vulnerability’s exploitation status before taking action.

3. Don't Forget Third-Party Software

It's easy to focus on major software like Windows or macOS and forget about everything else. Browsers, PDF readers, office productivity suites, and specialized business applications all have vulnerabilities. Include all software in your patching strategy. An unpatched browser on a single machine could compromise your entire network.

4. Decommission End-of-Life (EOL) Software

Running software that is no longer supported by its vendor is a ticking time bomb. When a vendor announces that a product has reached "end-of-life," it means they will no longer release security patches for it. Continuing to use it leaves you permanently vulnerable to any new flaws that are discovered. You should audit your software for supportability at least monthly according to the Center for Internet Security's (CIS) Critical Security Control 2.2.

The Bottom Line: Patching is Not an Option, It's a Requirement

The most common and damaging cyberattacks often exploit vulnerabilities we already know about. A strong patch management discipline is not a burden; it’s a non-negotiable part of a healthy cybersecurity posture. It protects your data, your reputation, and your bottom line.

By making patching a priority, you're not just closing a door; you're building a fortress against the threats that are already out there. Let's work together to make your organization resilient against the most sophisticated bad actors.