Legacy System Vulnerabilities: Still Here, Still Critical, Still Exploitable.

May, 2025 | By Carla Vieira

This article is about a threat that isn't making splashy headlines but poses a significant risk to business security: legacy systems still operating within our critical infrastructure. They often remain for legitimate business reasons, but while we are all laser-focused on AI-driven attacks and the latest zero-days, when was the last time you considered the true risk of that Windows XP machine in your industrial controls, the unpatched SMBv1 protocol in your logistics chain, or that ancient Solaris box in the finance department?

Recent threat intelligence reports consistently highlight that legacy operating systems remain high-value targets (why would they not?). Attackers are fundamentally opportunistic, targeting the path of least resistance. According to Verizon's 2025 Data Breach Investigations Report, breaches caused by exploiting vulnerabilities surged by 34% in the last year, demonstrating a clear focus on unpatched systems. An unsupported OS like Windows XP provides the perfect low-effort, high-reward opportunity that cybercriminals actively seek out. One more report on the matter: Honeywell's 2025 threat report revealed a 46% surge in ransomware attacks against industrial systems, many of which still rely on older, embedded Windows versions. Because these legacy systems cannot run modern security software, they run the risk of becoming unmonitored entry points.

⚠️ Heads up: If your security lab can't mimic these older environments, are you really geared up to defend against the attacks that are still successfully breaching businesses today?

Building a Modern Lab to Analyse Legacy System Vulnerabilities

How do you test vulnerabilities designed for older x86 systems when your primary machine runs on a completely different architecture, like Apple Silicon?  I realized I had to rebuild my approach and find a way, which involved a few tricks, so I wrote this blog to save you the headache. UTM + QEMU worked to create a full x86 emulation, even on a M-4 Mac. In the Australian App Store, the UTM app cost me under AUD$15.

With this setup, legacy system vulnerabilities can be recreated and analyzed, including:

• Launching MS08-067 or EternalBlue attacks against a vulnerable Windows XP or Server 2003 guest.

• Analyzing web-based flaws like Heartbleed on an older Linux server environment.

• Practicing and defending against network-level exploits like SMBv1 relay attacks.

The Business Value of Labs to Analyse Legacy System Vulnerabilities

Security team need to see the reality of what's still running out in the wild, not just what’s trending on security news sites.

With this lab, you can:

• Train your analysts: Let them get their hands dirty with attack paths they might otherwise only read about (but are definitely still active!).

• Ace compliance audits: Show tangible proof that you're not ignoring legacy risk.

• Model risk like a pro: Simulate how attackers actually pivot through these older, softer targets to get to your crown jewels.

• Put your shiny new tools to the test: Can your modern EDR or SIEM really spot these old-school exploits? Time to find out!

It's Not Nostalgia, It's Reality

As the reports from Verizon and Honeywell confirm, legacy systems are a major, present-day threat vector. This reality persists because organizations are often paralysed by the cost and complexity of upgrading, especially when relying on core software that feels like it was written in 1879 by a developer who has long since vanished, leaving little documentation behind (exageration intended).

So let's be crystal clear: this isn't about a fondness for old software. It's about confronting real, active, vulnerable systems that are, all too often, dangerously ignored. Your modern defenses are crucial, but they're not the whole picture if you're not also looking backward to secure what’s still actively chugging along from previous tech generations. Let's make sure we're all prepared for the threats of yesterday that are still knocking on doors today!

I can't wait to share the next projects that we will run on this setup. Get yourself ready and stay tuned! Here is your guide.

#LegacySecurity #CyberResilience #InfoSec #ThreatModeling #DigitalForensics #SecurityLabs #cvcyberdev