Organizations create massive volumes of data every day — emails, logs, backups, documents, and system records. While some of this information actively drives decisions, a surprisingly large portion is never touched again. This forgotten information is known as dark data, and it can quietly become one of the biggest data security liabilities.

Dark data refers to information that is collected and stored during normal operations but never analyzed, managed, or reviewed. It often exists in old backups, archived emails, system logs, legacy file servers, or duplicated documents. Because it’s rarely monitored, dark data remains “invisible” — until something goes wrong.

The problem isn’t just wasted storage. Dark data frequently contains sensitive information such as personal data, credentials, financial records, or intellectual property. When left unmanaged, it expands the attack surface and increases the risk of breaches, ransomware incidents, and compliance violations. Attackers actively look for outdated archives and forgotten storage locations because they’re often poorly protected.

Dark data accumulates for several reasons. Storage is cheap, systems generate data automatically, and organizations often follow a “save now, decide later” mindset. Over time, data ownership becomes unclear, governance weakens, and visibility disappears. What was once useful becomes digital clutter — but still carries risk.

It’s important to distinguish dark data from other data types. Unstructured data (like emails or videos) can still be actively used. Obsolete data may no longer have value but was once relevant. Dark data is different: it was collected but never used at all. These categories can overlap, but dark data is defined by its lack of purpose and oversight.

The hidden costs add up quickly. Dark data consumes storage, backup capacity, cloud subscriptions, and disaster recovery resources. It slows down analytics, complicates migrations, and makes it harder to trust reporting. In regulated environments, retaining unnecessary data can also lead to fines and audit failures when retention rules aren’t enforced.

From a security perspective, dark data is especially dangerous. It often bypasses modern protections like encryption, MFA, DLP, and monitoring. Breaches involving dark data can go undetected for months, exposing organizations to reputational and financial damage long after the data should have been deleted.

Reducing dark data starts with visibility. Organizations need to discover what data they have, classify it, assign ownership, and define retention policies. Old backups and archives should be reviewed, sensitive files encrypted, and irrelevant data safely removed. Regular audits help prevent dark data from quietly growing back.

Backups play a key role here. While backups can become dark data themselves if unmanaged, properly secured and well-governed backups help isolate old data, enforce retention rules, and protect sensitive information from ransomware or accidental deletion.

👉 **Want a deeper breakdown of dark data types, risks, and practical management strategies?** [Read the full article on the NAKIVO blog.](https://www.nakivo.com/blog/dark-data-and-data-security/)