Source code is one of your organization's most valuable assets — protecting it with a formal, auditable access policy is both a practical security control and a common ISO 27001 requirement; this post shows how to write, implement, and evidence a source code access policy aligned to ISO 27001 and your Compliance Framework, with templates and small-business examples you can adapt immediately.
Why a source code access policy matters (and the risk of not having one)
ISO 27001 requires documented information security policies and access control measures (see Annex A controls such as A.9 Access Control and A.12 Operations Security). Without a clear source code access policy you risk unauthorized code changes, credential leakage in repositories or CI logs, accidental exposure of IP, and supply-chain compromises that can lead to production incidents or customer data breaches. From a compliance perspective, auditors expect a documented policy, evidence of enforcement (logs, reviews), and periodic access reviews; failing to provide these can result in non-conformities on your Statement of Applicability (SoA) and ultimately jeopardize certification or contractual obligations.
Core components every ISO 27001-compliant source code access policy must include
A practical policy should be concise but complete: scope (repos, branches, pipelines), roles & responsibilities (maintainers, approvers, devs, security), access model (least privilege, role-based permissions, temporary access), authentication (SSO, MFA, key management), approval workflows for elevated or external access, onboarding/offboarding procedures, exception handling (break-glass), monitoring & audit requirements, retention of access logs as evidence, and a review cadence (at least annually or on major change). For Compliance Framework mapping, include a table in your policy that maps each clause to the relevant Compliance Framework control IDs and ISO A-controls so auditors can quickly verify coverage.
Implementation steps — practical, Compliance Framework–specific guidance
Start by performing a focused risk assessment on source-code confidentiality, integrity and availability (identify critical repos and owners). Create the policy document and include a control mapping to your Compliance Framework. Implement technical controls in phases: (1) centralize identity via SAML/SCIM SSO (Okta, Azure AD) and enforce MFA; (2) convert repo access to teams/groups and apply least-privilege roles; (3) enable branch protection and required status checks; (4) make secrets scanning and prevent commits with secrets; (5) enforce code review workflow rules (minimum approvals, CODEOWNERS for sensitive modules); (6) document and automate onboarding/offboarding connected to HR/IDP to ensure timely revocation. Keep evidence: screenshots of SSO enforcement, audit logs showing access changes, pull request (PR) histories, and periodic access review reports to satisfy your Compliance Framework auditors.
Small-business example: a 12-person startup
A 12-person startup using GitHub can implement the policy quickly: enable SAML SSO via Okta, require MFA for all accounts, create GitHub Teams (devs, ops, contractors), restrict write access to protected branches, enable required status checks and branch protection, use CODEOWNERS to require reviews from module owners, and store CI secrets in GitHub Actions secrets with environment protection (manual approvals for sensitive environments). Onboarding: HR opens a ticket, IT creates SSO account, and the new dev is added to a Team with least-privilege repo access; offboarding is automated via SCIM deprovisioning. Evidence collection: retain audit log exports monthly and attach them to the SoA for auditors.
Technical controls — concrete settings and tips
Implement these specific controls where applicable: require SAML/SSO with enforced MFA; disable shared accounts; use team-based RBAC and avoid granting org-wide admin rights; enable “Require pull request reviews before merging” with at least one required approver and block direct pushes to protected branches; enable commit signature verification (GPG or SSH key validation) to deter forged commits; rotate and limit scope of personal access tokens (PATs), and prefer OIDC short-lived tokens for CI/CD pipelines; use secrets management (HashiCorp Vault, AWS Secrets Manager) rather than storing secrets in repo variables; enable repository-level secret scanning and push protection; configure audit log retention per your Compliance Framework; and implement automated periodic access reviews (e.g., quarterly) with documented attestation from repo owners.
Source Code Access Policy - Template (adapt to your organization)
1. Purpose
- Protect confidentiality, integrity, and availability of source code and comply with ISO 27001 and Compliance Framework requirements.
2. Scope
- All source code repositories, branches, forks, CI/CD pipelines, and associated secrets used in development and deployment.
3. Definitions
- Repo Owner, Maintainer, Contributor, External Collaborator, Break-Glass Access, etc.
4. Roles & Responsibilities
- Repo Owner: approves access requests; performs quarterly access reviews.
- Security Team: configures security scanning, reviews exceptions.
- IT/Identity: manages SSO accounts and deprovisioning.
5. Access Requirements
- Authentication: SSO (SAML/SCIM) with MFA required.
- Authorization: RBAC, least privilege, temporary elevated access via documented approval.
- Code Review: protected branches require at least one (or two for critical repos) approvers; enforce CODEOWNERS where applicable.
6. Technical Controls
- Branch protection, required status checks, signed commits, secrets scanning, CI token rotation, ephemeral credentials.
7. Onboarding & Offboarding
- Onboarding tied to HR ticket; Offboarding uses SCIM deprovisioning within 1 business day.
8. Exceptions & Emergency Access
- Documented break-glass process; emergency access logged and reviewed within 3 business days.
9. Monitoring & Evidence
- Maintain audit logs, PR histories, access review records, and policy version history for audit.
10. Review Cycle
- Policy reviewed annually or after major incident.
Mapping to Compliance Framework: [table mapping policy sections to framework control IDs and ISO Annex A controls]
Adapt the template by filling in names, tool-specific procedures (e.g., GitHub Organizations vs GitLab Groups), retention periods required by your Compliance Framework, and the control mapping table referenced in the template.
Compliance tips and best practices: integrate the policy into your onboarding playbook so new hires automatically receive the right repo access; use automation (SCIM, IaC for repo provisioning, GitOps) to reduce human error; log all access changes and store logs in a centralized SIEM with at least the retention period required by your Compliance Framework; run periodic mock audits and tabletop exercises to validate break-glass and incident response workflows; and treat external contributors as a separate risk category with time-limited, minimal access and mandatory NDAs.
In summary, a robust ISO 27001-compliant source code access policy is a mix of clear written rules, mapped controls for your Compliance Framework, and enforceable technical settings. For small businesses, focus on centralized identity, least privilege, branch protection, secrets hygiene, automated onboarding/offboarding, and evidence collection — these steps reduce risk, make audits smoother, and materially improve your security posture.
