Essential Eight - Patching Operating Systems

September 2025

The Hidden Cost of Running on Outdated Operating Systems

This article is the second in Matrium Technologies’ Essential Eight Blog Series, where we unpack each of the Australian Cyber Security Centre’s (ACSC) eight key mitigation strategies. Our aim is to help business leaders understand what each control means, why it matters, and how to implement it in practical terms.

In this post, we look at Patch Operating Systems - a critical safeguard that too often slips through the cracks.

What “Patch Operating Systems” Really Means

Every computer, server, or device in your organisation runs on an operating system (OS) - Windows, macOS, Linux, and many others. Vendors regularly release patches to fix flaws, strengthen security, and improve stability.

When organisations delay or ignore these patches, attackers take advantage. In fact, many cybersecurity incidents - from ransomware outbreaks to espionage campaigns - exploit vulnerabilities that already had fixes available but weren’t applied.

For executives, the takeaway is simple: running an unpatched OS is like using outdated locks on every office door. It might look fine, but criminals already know how to break in.

Why It Matters for Your Business

• Prime target for attackers – Cybercriminals and state actors routinely scan the internet for machines running unpatched OS versions.

• Ransomware loves old systems – Many of the most damaging ransomware campaigns have relied on known OS flaws.

• End-of-life systems are a ticking time bomb – Once a vendor stops supporting an OS, no new patches are released. Continuing to run it invites trouble.

• Operational risk – A compromised OS can lead to downtime, lost productivity, and costly incident response.

Practical Steps to Implement

Building discipline in OS patching doesn’t have to be overwhelming. Leaders can guide teams to take practical steps such as:

1. Maintain an asset inventory – Know every server, laptop, and device in your environment.

2. Apply patches promptly – Prioritise internet-facing servers and business-critical systems.

3. Automate where possible – Use centralised patch management tools to streamline updates.

4. Plan for end-of-life – Replace or upgrade systems before vendor support expires.

5. Test before deployment – Especially in production environments, ensure patches don’t break critical business applications.

The Maturity Journey

The Essential Eight Maturity Model provides clear examples of what patching maturity looks like in practice:

• Maturity Level 1 (Basic Protection): Security patches and updates for operating systems are applied within one month of release.

• Maturity Level 2 (Improved Protection): Security patches for operating systems are applied within two weeks, prioritising critical updates. Systems not supported by vendors are replaced or isolated.

• Maturity Level 3 (Strongest Protection): Security patches for internet-facing services and critical servers are applied within 48 hours. Vulnerability scanning is used at least weekly to confirm compliance, with automated tools ensuring consistent coverage across the business.

This staged approach shows how organisations can move from “patching when convenient” to a structured, proactive defence.

Final Word

Outdated operating systems aren’t just a technical issue - they’re a business risk. They open the door to ransomware, data breaches, and regulatory headaches that no executive wants to face.

By investing in disciplined OS patching, organisations reduce their attack surface and gain confidence that their digital foundation is secure.

This is the second article in Matrium’s Essential Eight Blog Series. Next, we’ll explore Multi-Factor Authentication (MFA) - why passwords alone are no longer enough to protect your business.

Matrium Technologies helps organisations of all sizes achieve and maintain Essential Eight compliance, providing the expertise and solutions needed to strengthen cyber resilience.