Ghost assets: the greatest risk is the one you cannot see

In every IT, OT or IoT infrastructure there is a risk that rarely receives the attention it deserves: that of “ghost assets.” This is not a new threat nor an unknown technological category, but rather components that, while still part of the infrastructure, fall outside the radar of those who should be managing them.

It often happens that, over time, certain technologies remain connected to the infrastructure even though they no longer serve their original function. A server may stay powered on after a migration, without anyone formally shutting it down or decommissioning it; an application developed for an experimental project is forgotten once the initiative ends; an IoT device installed for a test remains silently active despite no longer being useful. Likewise, outdated firewall rules continue to exist even if they no longer match current traffic, and user accounts linked to former employees or vendors stay active far longer than they should.

Neglected because they are silent, excluded from normal update processes and invisible in official inventories, ghost assets end up living on the margins of the infrastructure, in a gray zone where no one notices them and no one takes care of them. It is precisely this condition of invisibility that, over time, turns them into the perfect target: the most exposed weak point, easily exploited by an attacker to gain unexpected access and pave the way to the core of the network.

Invisibility as a risk factor

The insidious nature of ghost assets lies in their very invisibility. An uncatalogued asset does not appear in inventories, does not receive security patches, is not included in hardening plans or in vulnerability management processes. In other words, it does not exist for defenders—but it certainly does for attackers.

This leads to two immediate consequences. The first concerns operational security: a single forgotten node can compromise the entire perimeter, taking advantage of the complex interconnections between systems. The second, equally critical, concerns regulatory compliance: directives such as NIS2 (EU 2022/2555), DORA, or standards such as ISO/IEC 27001:2022 and IEC 62443 require a complete inventory of digital assets. The presence of ghost systems therefore represents a structural violation, with potentially devastating legal and reputational consequences.

Recent statistics (Ponemon Institute 2023) show that 67% of companies admit they do not have full visibility of their IT/OT perimeter, and on average, 30% of assets are not catalogued. ENISA (2024) found that more than 20% of cyber incidents in Europe originate from obsolete or forgotten systems. The average cost of a data breach related to ghost assets is USD 4.45 million, with detection times 30% longer than incidents caused by monitored assets (IBM, 2023).

The limits of traditional approaches

Many organizations, convinced that manual control equals accuracy, continue to base asset discovery on manual or semi-automated activities, supported by operator checklists. But in hyperconnected and distributed ecosystems, where cloud environments, legacy data centers, IoT devices and OT systems coexist, human error is not a possibility: it is a certainty.

A manual inventory becomes obsolete as soon as it is completed, because the network has already changed: new devices connect, others are decommissioned, applications migrate to the cloud. The result is a partial map that no longer reflects the reality of the infrastructure.

Gartner predicts that by 2026, 75% of OT organizations will experience at least one major incident originating from unmonitored assets or shadow IT. This confirms that the traditional approach is insufficient and risks becoming a systemic point of failure.

The new way: from visible to invisible

If the greatest risk is the one you cannot see, the answer is to move toward total and continuous visibility. And this is only possible through an automated, data-driven approach capable of scanning the entire network in real time, detecting every connected asset, reconstructing their relationships, and generating a digital twin of the infrastructure.

This virtual model, constantly updated, makes it possible to:

• identify forgotten or uncatalogued systems;
• understand how threats and vulnerabilities spread across heterogeneous assets (IT, OT, IoT);
• simulate what-if scenarios to assess the impact of an attack or configuration change;
• provide a risk map that does not simply list vulnerabilities, but connects them directly to business processes.

The most advanced techniques are based on continuous asset discovery with passive network monitoring tools and the use of machine learning–based anomaly detection algorithms. In addition, the integration of an extended SBOM (Software Bill of Materials) covering IoT/OT ensures visibility along the supply chain, reducing the risk of exploits linked to untracked components.

Conclusion: what you cannot see can hurt you

Ghost assets are not a minor detail nor a problem that can be postponed: they are the most dangerous form of vulnerability because they do not generate visible signals—until it is too late. The real difference between a resilient organization and one that only appears resilient lies not in the number of defense tools deployed, but in the ability to make the invisible visible, eliminate blind spots, and transform risk management from a static exercise into a continuous process.

To put it in numbers: an uncatalogued asset is three times more likely to become an attack vector than one that is inventoried and monitored (ENISA Threat Landscape 2023).

The true weak point is not what you control, but what remains in the shadows without you realizing it.