03.16.01
Security Engineering Principles
Apply security engineering principles to build security expectations into engineering, unsupported components, and external services for CPCSC Level 2 readiness.
CPCSC Level 2 Control
Last updated June 25, 2026
03.16.03System and services acquisition
CPCSC Level 2 03.16.03: External System Services
Apply external system services to build security expectations into engineering, unsupported components, and external services for CPCSC Level 2 readiness. This guide separates the official ITSP.10.171 control language from practical implementation, evidence, auditor questions, and related controls.
Formal Control Language
Official ITSP.10.171 wording for 03.16.03. Use the Cyber Centre publication and contract requirements as the source of truth for certification, assessment, or procurement submissions.
- Require the providers of external system services used for the processing, storage, or transmission of specified information, to comply with the following security requirements: [Assignment: organization-defined security requirements]
- Define and document user roles and responsibilities with regard to external system services including shared responsibilities with external service providers
- Implement processes, methods, and techniques to monitor security requirement compliance by external service providers on an ongoing basis
Contains information sourced from Government of Canada material used under the Open Government Licence - Canada.
What This Means In Plain English
External System Services is part of the CPCSC Level 2 System and services acquisition family. This is about building security into systems, purchases, unsupported technology decisions, and external service relationships before they become assessment problems.
For a founder, CISO, engineer, or compliance owner, the practical question is whether external system services is visible in real operating evidence: a setting, workflow, ticket, log, approval, review, or exception record that can survive an external assessment.
Level 2 is different from Level 1 because the evidence has to survive an external assessment. A policy statement helps, but the stronger answer is a record that shows who did the work, when it ran, what system setting or workflow enforced it, and how exceptions were handled.
How To Implement It
1
Define the in-scope systems, owners, users, vendors, and data flows affected by external system services.
2
Apply secure engineering principles, manage unsupported components, define external service requirements, and include security requirements in procurement and vendor management.
3
Translate the formal requirement into one or two operating procedures: who performs it, how often, where it is recorded, and who approves exceptions.
4
Configure the relevant systems so the control is enforced by identity, endpoint, cloud, network, ticketing, monitoring, vendor, or documentation workflows rather than memory.
5
Keep evidence in a consistent folder, GRC system, ticket queue, or audit workspace so an assessor can trace the control from requirement to implementation to review.
Evidence Normally Gathered
External System Services: secure design reviews.
External System Services: unsupported component register.
External System Services: vendor security requirements.
External System Services: service agreements.
External System Services: architecture decision records.
External System Services: owner assignment and review cadence.
External System Services: exception, remediation, or POA&M records when the control is not fully implemented.
Common Auditor Questions
Where is external system services implemented in the in-scope environment?
Who owns external system services, and how do they know it is operating?
Show the evidence that proves external system services ran during the assessment period.
What happens when external system services fails, is bypassed, or has an exception?
How does this control connect to the system security plan, risk register, POA&M, and related CPCSC controls?
Sources
Source and attribution.
Formal control language is sourced from the Canadian Centre for Cyber Security ITSP.10.171 publication. CPCSC Level 2 assessment context references the Government of Canada CPCSC program overview and ITSP.10.171-01 assessment guidance.
CPCSC Program OverviewITSP.10.171ITSP.10.171-01Open Government Licence - Canada