ISM-1116 ASD Information Security Manual (ISM)

Ensure Separation Between Top Secret and Other Cabinets

Ensure there's a visible gap between top secret and other cabinets for security reasons.

Preventative TOP SECRET ASD Information Security ManualGuidelines for communications infrastructure secure facilities environment separation labelling

🏛️ Framework

ASD Information Security Manual (ISM)

🧭 Control effect

Preventative

🔐 Classifications

🗓️ ISM last updated

Feb 2023

✏️ Control Stack last updated

19 Mar 2026

🎯 E8 maturity levels

N/A

Guideline

Guidelines for communications infrastructure

Section

Cabling infrastructure

Topic

Physical Separation of Cabinets and Patch Panels

Official control statement

A visible gap exists between TOP SECRET cabinets and non-TOP SECRET cabinets.

Source: ASD Information Security Manual (ISM)

Plain language

This control is about keeping top-secret information separate from other confidential information by physically separating their storage cabinets. This matters because if all your sensitive papers are stored together, there's a higher risk of someone accessing information they shouldn't, which could lead to leaks or misuse of critically sensitive data.

Why it matters

If TOP SECRET and non‑TOP SECRET cabinets are not visibly separated, staff may misfile items, causing improper storage, spillage and potential compromise of TOP SECRET holdings.

Operational notes

Maintain a clearly visible gap between TOP SECRET and other cabinets; label TOP SECRET storage prominently and confirm the gap remains during routine physical security checks.

Implementation tips

Facility manager should identify the physical locations of top-secret and other cabinets. Use a tape measure to ensure there's a noticeable gap of at least one metre between them to make sure they are distinctly separate.
Office manager should label the cabinets appropriately. Clearly mark the top-secret cabinets as such to reduce confusion about which cabinets contain which level of information.
Security personnel should ensure the physical layout supports separation. Conduct a walkthrough to confirm that the gap is present at any time, and consider adding physical barriers if needed.
IT manager should document the layout and any changes in a secure record. Keep a floor plan that shows the position and separation of each cabinet stored in a secure digital file and update it whenever changes happen.
Staff responsible for the documents within the cabinets should undergo training. Understanding why this separation is important can reinforce the importance of maintaining these physical barriers.

Audit / evidence tips

Ask: the facility layout plan showing cabinet locations: Request a copy of the site's current floor plan

Good: will show a minimum one metre gap clearly marked on the plan
Ask: photographs or videos of the cabinet setup: Request recent media that depicts the cabinets' actual locations

Good: will show that the cabinets are not only separated, but that the separation is easily visible
Ask: to see the training records of responsible staff: Request documentation of training sessions describing the separation requirement

Good: includes regular training that discusses physical security requirements
Ask: about incident reporting for breaches or concerns: Request logs or records of any issues reported regarding cabinet separation

Good: will list resolved issues and any preventive actions taken
Ask: the security policy document covering cabinet setup: Request the part of the security policy that outlines cabinet separation

Good: includes clear guidance for maintaining these processes

Cross-framework mappings

How ISM-1116 relates to controls across ISO/IEC 27001, Essential Eight, and ASD ISM.

These mappings show relationships between controls across frameworks. They do not imply full equivalence or certification.

ISO 27001

Control	Notes	Details
Partially meets (2)
Annex A 7.3	ISM-1116 requires a visible gap between TOP SECRET and non-TOP SECRET cabinets as a physical security and handling safeguard for classifi...
Annex A 7.8	ISM-1116 requires organisations to maintain a visible physical gap between TOP SECRET cabinets and non-TOP SECRET cabinets to reduce the ...
Related (1)
Annex A 7.5	Annex A 7.5 requires organisations to design and implement measures that protect physical infrastructure from threats, including preventi...