Secure TOP SECRET Cable Wall Exits
Ensure TOP SECRET cables that pass through walls to lower security areas are protected by conduits and sealed.
Plain language
If you have cables for sensitive or secret information running through walls into places that aren't as secure, it's vital to protect those cables. By putting the cables in a sturdy cover and sealing them properly, you ensure that no one can tamper with them or have unauthorised access, which helps to keep your sensitive information safe.
Framework
ASD Information Security Manual (ISM)
Control effect
Preventative
Classifications
TS
ISM last updated
Nov 2021
Control Stack last updated
19 Mar 2026
E8 maturity levels
N/A
Section
Cabling infrastructureTopic
Wall PenetrationsOfficial control statement
Where wall penetrations exit a TOP SECRET area into a lower classified area, TOP SECRET cables are encased in conduit with all gaps between the TOP SECRET conduit and the wall filled with an appropriate sealing compound.
Why it matters
If TOP SECRET cables are not encased in conduit and wall gaps sealed, adversaries could intercept or tamper with signals as they exit to lower classified areas.
Operational notes
Inspect TOP SECRET wall exit conduits and verify all annular gaps are fully filled with suitable sealing compound; repair cracks, shrinkage or loose fittings immediately.
Implementation tips
- Facility Managers should work with a security contractor to assess wall penetrations where TOP SECRET cables pass through. They should identify any existing unprotected exits to ensure all cables are correctly encased. This can be done by physically inspecting the cable paths throughout the facility.
- Security contractors should install conduits to encase any exposed TOP SECRET cables. They should also ensure that every entry point of the conduit is sealed with a compound that meets security standards, to prevent tampering. This requires purchasing suitable sealing compounds and applying them at each identified location.
- IT security officers should regularly review the conduit system annually to ensure the integrity and security of the installations. This involves using a checklist to verify that all conduits are intact and seals are undamaged, and documenting any required repairs.
- Building maintenance teams should be trained on the importance of physical security for cabling and should perform routine checks for any unsealed or deteriorating sections of conduit. Training can include an explanation of what to look for during routine maintenance walks and who to notify for resolutions.
- System owners should document the locations of these conduits and seals in their security protocols, ensuring all staff are aware of these critical areas. This can be achieved by maintaining a detailed map or diagram in the office explaining where these lines are located and what to do if something looks suspicious.
Audit / evidence tips
- AskBuilding plans that show the location of all sand-witched conduits for TOP SECRET areas GoodIncludes a clear, updated map with annotations of all conduits and seals
- GoodWould show regularly logged inspections with detailed findings and resolution timelines
- AskTo see the inventory of sealing compounds used GoodShould provide product details and compliance verification
- GoodIncludes a course curriculum covering conduit security and a log of recent training attended by all relevant staff
- AskSecurity protocols related to cable handling and protection GoodIs a document that explicitly outlines procedures for cable protection, including contingency plans if a conduit is breached
Cross-framework mappings
How ISM-1122 relates to controls across ISO/IEC 27001, ISO/IEC 42001, Essential Eight, and ASD ISM.
ISO 27001
| Control | Notes | Details |
|---|---|---|
| link Related (1) expand_less | ||
| Annex A 7.12 | Annex A 7.12 requires that power and data cabling is protected from interception, interference or damage | |
These mappings show relationships between controls across frameworks. They do not imply full equivalence or certification.