You cannot protect what you do not know you have.
Annex A 5.9 exists to ensure organisations identify, understand, and take ownership of their information and associated assets, so that security controls are applied deliberately rather than blindly.
This control is foundational. Every other security decision - risk assessment, classification, access control, incident response - depends on knowing what assets exist and who is responsible for them.

Annex A 5.9 of ISO 27001:2022 focuses on maintaining an inventory of information and other associated assets, including ownership.
At a practical level, this means:
The control does not mandate a single inventory, a specific tool, or exhaustive technical detail. The level of formality should be proportionate to the organisation’s size, complexity, and risk profile.
The outcome matters more than the format.
Information assets are not limited to databases and servers.
They include:
Without a clear understanding of these assets:
Annex A 5.9 ensures organisations establish visibility and ownership over the assets that matter to their operations and security.
It also supports better decision-making by making asset value and importance explicit.
A pragmatic approach to Annex A 5.9 usually includes the following elements.
Start by identifying assets that are important to the organisation’s objectives and information security.
This often includes:
The focus should be on relevance, not exhaustiveness.
Each asset should have an identified owner who is accountable for its protection.
Ownership typically includes responsibility for:
Ownership does not imply technical administration — it implies accountability.
Asset information should be recorded in a way that is:
Some organisations maintain multiple inventories for different purposes. That is acceptable, provided information is consistent and usable.
The control does not require a single, centralised register.
Asset inventories lose value quickly if they are not maintained.
Common triggers for review include:
Updates should be part of normal operational processes where possible.
An inventory is not an end in itself.
It should support:
If the inventory is not being used, it is likely too complex or misaligned.
Asset management works best when it is practical, not theoretical.
Annex A 5.9 is about visibility, ownership, and informed decision-making.
When information and associated assets are clearly identified:
An asset inventory does not need to be perfect. It needs to be useful and current.
That is the outcome Annex A 5.9 is designed to achieve.
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