How Outdated Systems and Legacy Software Are Fueling Modern Cyber Attacks

Outdated software and legacy systems lurk in nearly every enterprise IT environment. These remnants of technical debt – whether it’s an end-of-life operating system, unsupported database, or deprecated library – might quietly keep business processes running today, but they also quietly compound cyber risk. In fact, technical debt is almost universal: a recent Forrester survey found only 21% of IT decision-makers reported having no significant tech debt, while 79% admitted their organizations face moderate to high levels of accumulated technology debt​. 

Much like financial debt, unresolved tech debt “accrues interest” over time, requiring more resources to fix and weakening operational resilience, including security. For Chief Information Security Officers (CISOs) and engineering leaders, this hidden risk can be a ticking time bomb if left unmanaged.

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Tech Debt and EOL Software as an Exponential Cyber Risk

Out-of-support software and systems create an outsized security risk. Research shows that 20% of critical enterprise assets run end-of-life (EOL) open source software containing high-severity vulnerabilities, and nearly half of known exploited vulnerabilities (such as those in CISA’s KEV catalog) are tied to outdated, unsupported software​. Notably, vulnerabilities in EOL/EOS systems are 4x more likely to be weaponized by attackers​, making legacy technology a high-priority target for cyber adversarie

The reason outdated technology is so risky is simple: if a system is no longer supported, it no longer gets security patches.

New vulnerabilities discovered in an end-of-life product will remain unpatched – essentially an open door for attackers. Over time, the number of unpatched flaws grows. One analysis found that an average end-of-life software image accumulates 218 new vulnerabilities every six months after support ends​. Attackers are well aware of this reality. 

Verizon’s latest Data Breach report revealed that exploiting known vulnerabilities is now the initial breach vector in 20% of incidents, on par with stolen credentials. Most of these exploited vulnerabilities are not zero-days, but known bugs in outdated systems that organizations failed to patch or retire.

(Gartner famously predicted that 99% of exploited vulnerabilities are known to IT for at least a year, underlining how prevalent unaddressed tech debt is in breach scenarios.)

Real-world incidents provide stark examples. The infamous WannaCry ransomware outbreak devastated organizations worldwide by exploiting a Windows bug, and 98% of machines hit by WannaCry were running an end-of-life Windows 7 OS. Likewise, when the critical Log4Shell vulnerability in Log4j was disclosed, over 50% of affected application installations were already “end-of-support” on the announcement day​ , meaning no vendor patches were available, forcing a frantic scramble for mitigations. Even well-resourced agencies have fallen victim; a 2023 US Federal Agency breach was traced to servers running an unsupported Adobe ColdFusion version. In each case, tech debt in the form of outdated software became an incident multiplier, turning a manageable vulnerability into a major security crisis.

Attackers actively seek out these weak links. Nearly 46% of CISA’s Known Exploited Vulnerabilities (KEV) catalog are linked to end-of-service software or OS platforms. The longer an obsolete system stays in your network, the longer attackers have to hammer away at its flaws. It’s no surprise, then, that security teams view aging technology as an “exponential multiplier” of cyber risk. The risk isn’t just theoretical or compliance-related—it manifests in breach statistics and live exploits on unpatched legacy systems every day.

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Why Does Tech Debt Keep Piling Up (Out of Sight)?

If legacy systems are so dangerous, why do they persist in today’s enterprises? The reality is that engineering teams don’t intend to create security liabilities – technical debt often accumulates as an unintended byproduct of business decisions and resource trade-offs. Many organizations prioritize upgrades and refactoring only when something breaks or a crisis hits, rather than as a continuous risk mitigation practice. In other words, cyber risk isn’t always considered when deferring an upgrade – the focus is usually on avoiding business disruption or saving cost in the short term​. As a result, outdated systems can fly under the radar of security teams until a major vulnerability (or breach) forces everyone’s hand.

Several common scenarios lead to this hidden accumulation of risk:

• “If it ain’t broke, don’t fix it” mindset: IT departments often leave legacy applications running as long as they appear stable. The primary concern for a CIO or engineering lead might be uptime and user productivity, not the security profile of the software version. Thus, a database that’s several versions behind, or an unpatched middleware stays in production because it still works – all while silently accumulating critical vulnerabilities.
• Competing priorities and resource constraints: Development teams frequently incur tech debt by choosing speed over perfection, using quick fixes, older libraries, or skipping upgrades to meet deadlines. These decisions “make sense at the time” to deliver business value, but the debt remains. Over the years, layer upon layer of such shortcuts create a fragile stack of obsolete components. Most organizations lack a clear inventory of these latent issues, and security teams may not be aware of vulnerable old components tucked inside applications.
• Siloed ownership of upgrades: IT operations in many companies own system upgrades and maintenance, while security teams focus on incidents and vulnerabilities. This silo can be dangerous. CIOs and IT managers worry about patching causing downtime or new versions breaking compatibility so that they may defer updates. Meanwhile, CISOs might assume everything is up to date if no one flags it. According to Qualys' research, security often only intervenes reactively – e.g., during a Log4Shell-type emergency – rather than having a proactive seat at the table for lifecycle management. If security and IT aren’t regularly sharing data, critical risks tied to tech debt can go unnoticed until an attacker exploits them.

The upshot is that technical debt tends to be “out of sight, out of mind” for security teams until it’s too late. Outdated systems usually present operational annoyances before they present obvious security problems – slow performance, lack of vendor support, compatibility issues, etc. It’s easy for leadership to treat tech debt as purely an IT maintenance issue. But as we’ve seen, every unpatched legacy system is essentially an unlocked door in your cyber defenses. To close those doors, organizations need to bring security thinking into the way they track and tackle tech debt.
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A Framework for Identifying and Addressing Tech Debt Risk

Acknowledging the problem is step one – the next step is taking action. CISOs and engineering leaders should collaborate to highlight hidden tech debt and systematically reduce the risk from outdated technology. Below is a practical framework (a checklist of key steps) to identify and address tech debt before it leads to an incident:

1. Discover and Inventory Your Assets: You can’t manage what you don’t know about. Begin with a comprehensive asset inventory that catalogs hardware, operating systems, applications, and third-party components across your environment. Crucially, track the end-of-life (EOL) or end-of-support (EOS) status for each asset – e.g., software versions and their support sunset dates. Many organizations are surprised to find how many assets are already past EOL or will be within the following year. Modern IT asset management tools or SBOM (Software Bill of Materials) analysis can assist in uncovering outdated open-source libraries and shadow IT components.
2. Assess and Prioritize Risk: Not all tech debt carries equal risk. For each EOL/EOS asset identified, determine the exposure and importance of that system. Ask questions like: Is it internet-facing or internal? Does it house sensitive data or business-critical functions? Are there known high-severity vulnerabilities associated with that obsolete version​? Nearly 20% of enterprises' critical assets have installed high-risk EOL software, so pay special attention to any legacy systems underpinning your “crown jewels.” Use vulnerability scanners to identify unpatched CVEs on those assets, and consult threat intelligence (e.g., the CISA KEV list) to see if old versions in your stack map to known exploited bugs. This risk assessment allows you to rank tech debt by its potential to harm the organization.
3. Plan Remediation and Upgrades (Proactively): Armed with a prioritized list, work with IT and product teams to develop an upgrade plan for the highest-risk items. Don’t wait until the support expiration date arrives – begin planning 6–12 months before EOL for critical systems. Schedule regular technology refresh cycles as part of your roadmap (just as you schedule feature releases or infrastructure expansions) whenever possible. For each risky, outdated component, identify the path to remediation: Is there an update or patch available? Do we need to migrate to a newer platform or refactor code? Having a forward-looking plan helps avoid the last-minute scramble when a zero-day hits an already obsolete system. Importantly, align this plan with IT’s budgeting and maintenance calendars. By syncing security-driven priorities with the IT change management (e.g., updating the CMDB and maintenance windows), you ensure that upgrades are budgeted and not continually deferred.
4. Implement Controls for “Can’t Fix Now” Scenarios: In reality, some legacy systems can’t be upgraded overnight – perhaps they are tied to revenue-generating services or require a long refactor. For these cases, mitigate the risk with compensating controls. Consider tactics like network segmentation (isolating the vulnerable system from critical networks), virtual patching or Web Application Firewalls (to shield known exploits), stricter access controls, and enhanced logging/monitoring of the system’s activity​. For example, if you must keep an outdated server running temporarily, ensure it’s not exposed directly to the internet and that you have detection in place if an attacker probes it. These measures can buy time while you work on a permanent fix.
5. Establish Ongoing Observability and Maintenance: Treat technical debt reduction as an ongoing program, not a one-time project. This is where observability and continuous monitoring come in. Leverage infrastructure and application monitoring to watch for signs of stress or compromise on older systems (e.g. unusual spikes in traffic which could indicate exploitation attempts). Continuously track newly announced end-of-support dates – technology vendors and projects regularly publish EOL notices, so incorporate those updates into your asset inventory. Likewise, stay aware of emerging vulnerabilities that might suddenly make a previously “benign” legacy system an urgent risk. Some organizations institute a “tech debt review” every quarter, bringing security, IT, and engineering together to review aging assets and progress on remediation. The key is maintaining visibility so that new tech debt doesn’t creep in unchecked as you address the old.
6. Foster a Collaborative Culture: Successful tech debt management spans multiple teams. Encourage a culture where engineering, IT, and security collaborate on lifecycle management. For instance, security teams should regularly share risk data about outdated systems with IT leadership​ , and engineering squads should include remediation tasks in their backlogs when planning new features. Make “security risk” a factor in deciding when to modernize a system, not just uptime or feature needs. By breaking down silos – perhaps via joint dashboards or cross-functional meetings – the organization can proactively tackle tech debt as a unified effort rather than a blame game after an incident.

Organizations can start turning hidden vulnerabilities into visible, manageable tasks using this framework as a checklist. The goal is to modernize and patch your environment on your schedule – before attackers set their schedule on you. As the saying goes, an ounce of prevention is worth a pound of incident response.

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HeroDevs: Your Safety Net for End-of-Life Software

Modernizing is the ideal, but what about the systems you can’t replace right now?

At HeroDevs, we know that end-of-life doesn’t mean end-of-use. Critical applications often run on frameworks the industry has left behind, but your business hasn’t. We created Never-Ending Support (NES): to keep legacy systems secure, compliant, and stable long after official support ends.

With HeroDevs, You Get:

• Ongoing CVE patching for EOL open source software like AngularJS, Node.js, Apache Tomcat, Spring, and more
  
  
• Security and compliance coverage without forced migrations or rebuilds
  
  
• Enterprise-grade SLAs and a drop-in replacement for the software you already use that integrates cleanly into your existing stack
  
  

We're not here to sell modernization timelines but to buy you time. NES gives your team the breathing room to plan upgrades on your terms, not under pressure.

Security leaders use HeroDevs to reduce cyber risk from legacy tech, empowering their teams to focus on delivering value. Because in a world where attackers target the slowest movers, standing still without support is no longer safe.

Don’t wait for the next ransomware headline or emergency patch scramble to address the tech debt in your organization. As we’ve learned, the cost of inaction is measured in breached data, downtime, and derailed projects. It’s time to shine a light on your hidden cyber risks and tackle them head-on. 

Herodevs is here to help. Contact us to schedule a tech debt risk assessment or learn how our modernization and observability solutions can safeguard your enterprise. Together, we can turn technical debt from a lurking danger into an opportunity, strengthening your security posture while enabling the innovations of tomorrow.