27 January 2026
On 26 November 2025, the Ministry of Defence (MOD) issued Industry Security Notice (ISN 2025/07), formally implementing the Cyber Security Model (CSM) v4 and retiring the interim measures that supported DEFCON 658 (ISN 2024/02).
In this white paper, we explain what the Cyber Security Model is, the Defence Standard (DEFSTAN) 05-138, and the Defence Cyber Certification (DCC).
AMR CyberSecurity supports many Prime Defence Suppliers and subcontractors within the Defence Supply Chain to assess, identify, and manage cyber security risks within their contracts. We have extensive experience in managing cyber security risk and has security-cleared consultants who can assist and support organisations with the CSM.
As a certified DCC Certification Body, AMR CyberSecurity can deliver both independent assessments or targeted consultancy to help organisations achieve and maintain compliance under the DCC scheme.
