Colour Code for TOP SECRET Cables
TOP SECRET cables must be red to ensure easy identification and compliance.
Plain language
This control is all about making sure cables that carry TOP SECRET information are easy to spot by colouring them red. This matters because if these cables aren't marked clearly, sensitive information might be mishandled or routed incorrectly, leading to potential security breaches.
Framework
ASD Information Security Manual (ISM)
Control effect
Preventative
Classifications
TS
ISM last updated
Feb 2023
Control Stack last updated
19 May 2026
E8 maturity levels
N/A
Section
Cabling infrastructureTopic
Cable ColoursOfficial control statement
TOP SECRET cables are coloured red.
Why it matters
If TOP SECRET cables are not clearly identified as red, staff may mishandle them, increasing the likelihood of disclosure and serious security incidents.
Operational notes
Inspect cable colour during installs and quarterly checks. Ensure TOP SECRET cables are red; re-label or replace any non-red cables immediately.
Implementation tips
- The IT team should survey the current infrastructure to identify all cables that handle TOP SECRET data. They can do this by reviewing existing network diagrams and checking against data classification records.
- Procurement should ensure that any new cable purchases meant for TOP SECRET data transmission are indeed red. They can achieve this by specifying red cables in purchasing agreements and confirming with suppliers.
- The facility manager should organise the relabelling of any existing TOP SECRET cables which are not red. This can be done by using red cable sleeves or covers and documenting these changes for reference.
- Security officers should train staff on recognising red cables as indicators of TOP SECRET data pathways. This can be achieved by workshops or informational posters around data handling areas, emphasising the importance of the red cable protocol.
- The IT infrastructure team should maintain an up-to-date inventory that marks which cables are carrying TOP SECRET data and ensure they are red. This can be done using asset management software and regular physical checks.
Audit / evidence tips
- AskThe current network cable inventory list GoodShows a detailed list with all TOP SECRET cables noted as red, matching the infrastructure map
- GoodIncludes invoices and communications confirming red cables for TOP SECRET use
- AskTraining records related to security procedures about cable recognition GoodProvides records showing staff have been trained recently about the significance of red cables
- AskTo see the documentation of any re-labelling activities for existing cables GoodIncludes detailed records of actions taken and ensures compliance with the red cable requirement
- GoodConfirms that all visible TOP SECRET cables are red and marked properly on-site
Cross-framework mappings
How ISM-1719 relates to controls across ISO/IEC 27001, ISO/IEC 42001, Essential Eight, and ASD ISM.
ISO 27001
| Control | Notes | Details |
|---|---|---|
| handshake Supports (2) expand_less | ||
| Annex A 5.12 | ISM-1719 requires a concrete classification-driven marking rule: TOP SECRET cables are coloured red to signal their sensitivity | |
| Annex A 7.12 | ISM-1719 requires TOP SECRET cables to be coloured red so they can be rapidly and reliably identified as highly sensitive cabling | |
These mappings show relationships between controls across frameworks. They do not imply full equivalence or certification.