Runbook 02 — Enterprise Container Registry Security Assessment

Runbook Information

Item	Details
Runbook ID	K8S-IMAGE-RUNBOOK-02
Category	Container Registry Security Assessment
Runbook Type	Enterprise Security Assessment
Primary Team	Cloud Security Engineering
Supporting Teams	DevSecOps, Platform Engineering, Kubernetes Security, SOC, Compliance
Estimated Duration	6–8 Hours
Assessment Frequency	Monthly / Before Production Releases
Supported Registries	Amazon ECR, Azure Container Registry, Google Artifact Registry, Harbor, OCI-Compatible Registries
Compliance Alignment	CIS Kubernetes Benchmark, NIST SP 800-190, NIST SSDF, SLSA, ISO 27001, SOC 2

Executive Summary

A container registry is one of the most critical components of the Kubernetes software supply chain.

Every workload deployed into Kubernetes ultimately depends upon images stored within trusted container registries.

A compromised registry can allow attackers to:

Replace production images
Introduce malware
Modify software dependencies
Remove rollback versions
Bypass security controls
Distribute malicious containers across the enterprise

This runbook provides a complete enterprise methodology for assessing registry security, governance, integrity, and operational readiness.

Enterprise Scenario

CloudNova Technologies operates multiple Kubernetes clusters supporting:

Customer-facing applications
Internal microservices
AI workloads
Financial systems
Healthcare platforms

Container images are stored across multiple registries:

Amazon ECR
Azure Container Registry
Harbor
Development registries

A recent security assessment identified several concerns:

Shared administrator accounts
Mutable production tags
Missing vulnerability scanning
Missing lifecycle policies
Excessive IAM permissions
Long-lived credentials
Public repositories
Missing registry audit logs
No replication strategy
Weak incident response procedures

The CISO has requested a complete enterprise assessment before approving additional production deployments.

Assessment Objectives

Validate:

Registry architecture
Repository governance
Identity and Access Management
Authentication methods
Least privilege access
Image integrity
Registry encryption
Vulnerability scanning
Image signing support
Repository lifecycle management
Audit logging
Monitoring
Backup strategy
Replication
Disaster recovery
Kubernetes integration
Compliance readiness

Enterprise Registry Architecture

                Developer

                    │

                    ▼

            CI/CD Pipeline

                    │

                    ▼

           Security Scanning

                    │

                    ▼

             Image Signing

                    │

                    ▼

        Enterprise Registry

      ┌─────────┼─────────┐

 Development  Staging  Production

      │          │          │

      └──────────┼──────────┘

                 │

                 ▼

      Kubernetes Clusters

                 │

                 ▼

       Runtime Monitoring

Assessment Scope

Review:

Registry Platform
Repository Structure
IAM Policies
Authentication
Repository Permissions
Registry Encryption
Vulnerability Scanning
Image Signing
Image Attestations
Tag Immutability
Lifecycle Policies
Audit Logging
Registry Monitoring
Replication
Disaster Recovery
Kubernetes Pull Access
CI/CD Integration

Required Tools

Tool	Purpose
Docker	Registry Validation
kubectl	Kubernetes Review
Trivy	Image Validation
Cosign	Signature Verification
Cloud CLI	Registry Administration
jq	JSON Parsing
Helm	Platform Validation

Registry Assessment Workflow

Registry Discovery

        │

        ▼

Repository Review

        │

        ▼

IAM Assessment

        │

        ▼

Scanning Review

        │

        ▼

Integrity Validation

        │

        ▼

Monitoring Review

        │

        ▼

Backup Assessment

        │

        ▼

Risk Assessment

        │

        ▼

Final Report

Phase 1 — Registry Discovery

Collect:

Registry Name
Registry Type
Cloud Provider
Version
Region
Owner
Environment

Identify:

Production Registries
Development Registries
Public Registries
Temporary Registries

Phase 2 — Repository Governance

Review:

Repository Naming Standards
Repository Ownership
Repository Classification
Business Owners
Technical Owners

Validate:

Development
Testing
Staging
Production

Confirm.

Repository documentation exists.

Phase 3 — Identity & Access Management Review

Review:

Registry Administrators
CI/CD Roles
Kubernetes Pull Roles
Developers
Security Team

Validate.

Least Privilege.

Review:

Shared Accounts
Service Accounts
Temporary Credentials

Reject.

Permanent Administrator Tokens.

Phase 4 — Authentication Assessment

Validate.

Authentication methods.

Preferred:

IAM Roles
Workload Identity
Managed Identity
Short-lived Tokens

Review.

Credential Rotation.

Reject.

Static Passwords.

Phase 5 — Repository Permission Review

Review.

Permissions.

Pull
Push
Delete
Policy Management
Admin

Confirm.

Production repositories:

Push access restricted.

Phase 6 — Registry Encryption Assessment

Validate.

Encryption.

At Rest
In Transit

Review.

TLS
KMS
Customer Managed Keys

Confirm.

Key Rotation.

Phase 7 — Image Integrity Assessment

Review.

Image Digests
Immutable Tags
Image Signing
Trusted Keys
Trusted Identities

Reject.

Unsigned Production Images.

Phase 8 — Vulnerability Scanning Assessment

Validate.

Registry Scanning.

Review.

Scan on Push
Continuous Scan
Critical Findings
High Findings

Confirm.

Deployment Approval Process.

Phase 9 — Repository Lifecycle Review

Review.

Lifecycle Policies.

Validate.

Retention
Cleanup
Rollback Images
Archive

Reject.

Unlimited Image Retention.

Phase 10 — Registry Monitoring Review

Review.

Monitoring.

Push Events
Pull Events
Delete Events
Login Events
Policy Changes

Confirm.

Security Alerts.

Phase 11 — Audit Logging Review

Review.

Logs.

Authentication
Image Push
Image Pull
Image Delete
Policy Changes
Repository Changes
IAM Changes

Confirm.

Central SIEM Integration.

Phase 12 — Registry Replication Review

Review.

Cross-region Replication.

Cross-account Replication.

Geo Redundancy.

Validate.

Recovery Objectives.

Phase 13 — Backup & Disaster Recovery Assessment

Review.

Registry Backup
Metadata Backup
Repository Restore
Recovery Time
Recovery Point

Confirm.

Periodic Recovery Testing.

Phase 14 — Kubernetes Integration Review

Review.

Image Pull Secrets
Workload Identity
Registry Access
Admission Controls
Signature Verification

Confirm.

Only Approved Registries used.

Phase 15 — CI/CD Integration Review

Validate.

Pipeline:

Build
Scan
Sign
Push
Verify

Confirm.

Failed Images blocked.

Phase 16 — Software Supply Chain Assessment

Review.

Build Provenance
SBOM
Image Signature
Trusted Registry
Admission Policies

Compare.

SLSA Requirements.

Phase 17 — Operational Readiness Assessment

Review.

Incident Response
Monitoring
Escalation
Documentation
Maintenance

Validate.

Operational Procedures.

Enterprise Registry Security Checklist

Control	Status
Private Registry	☐
Repository Standards	☐
Business Ownership	☐
IAM Least Privilege	☐
Short-lived Authentication	☐
Encryption at Rest	☐
TLS Enabled	☐
Scan on Push	☐
Continuous Scanning	☐
Image Signing	☐
Immutable Tags	☐
Trusted Identities	☐
Lifecycle Policies	☐
Rollback Images	☐
Registry Monitoring	☐
Audit Logging	☐
SIEM Integration	☐
Replication	☐
Backup	☐
Disaster Recovery	☐
Kubernetes Integration	☐
Admission Controls	☐
Evidence Collected	☐

Risk Classification

Critical

Public Production Registry
Shared Administrator Accounts
Unsigned Images
Mutable Production Tags
Registry Compromise
Missing Audit Logs

High

Missing Vulnerability Scanning
Excessive IAM Permissions
No Encryption
Missing Lifecycle Policies
Missing Backup

Medium

Weak Documentation
Manual Reviews
Missing Repository Labels

Low

Naming
Metadata
Cosmetic Improvements

Remediation Priorities

Immediate

Remove public access
Enable scan-on-push
Restrict administrator access
Enable immutable tags
Require image signing
Enable audit logging

Short-Term

Configure lifecycle policies
Integrate SIEM
Enable registry replication
Rotate credentials
Implement least privilege IAM

Long-Term

Automated registry governance
Continuous compliance monitoring
Cross-region disaster recovery
Automated image quarantine
Supply chain maturity improvements

Registry Security Assessment Matrix

Domain	Rating
Registry Architecture
Repository Governance
IAM
Authentication
Encryption
Vulnerability Scanning
Image Integrity
Lifecycle Management
Monitoring
Audit Logging
Backup
Disaster Recovery
Kubernetes Integration
Compliance

Ratings:

Effective
Partially Effective
Ineffective

Evidence Collection

Collect:

Registry Configuration
Repository List
IAM Policies
Authentication Methods
Scan Results
Lifecycle Policies
Registry Logs
SIEM Events
Backup Configuration
Replication Settings
Kubernetes Pull Configuration
Admission Policies
Assessment Results

Enterprise Registry Security Report

Assessment Name:

Enterprise Container Registry Security Assessment

Assessment Date:

Assessor:

Registry Platform:

Registry Region:

Environment:

Repositories Reviewed:

Critical Findings:

High Findings:

Medium Findings:

Low Findings:

Registry Encryption:

Image Signing:

Scan on Push:

Continuous Scanning:

Lifecycle Policies:

Immutable Tags:

Registry IAM:

Monitoring:

Audit Logging:

Backup:

Replication:

Disaster Recovery:

Overall Risk:

Recommendations:

Production Approval:

Approved

Conditionally Approved

Rejected

Success Criteria

The assessment is successful when:

All production registries are identified.
Repository governance is documented.
IAM follows least privilege.
Registry authentication is secure.
Images are scanned.
Images are signed.
Immutable tags are enforced.
Lifecycle policies exist.
Monitoring and logging are enabled.
Backups and replication are configured.
Kubernetes only pulls from approved registries.
Evidence supports compliance and audit requirements.

Operational Best Practices

Daily

Monitor image pushes
Review failed authentication attempts
Investigate critical vulnerability findings
Monitor registry availability

Weekly

Review repository permissions
Validate lifecycle policy execution
Verify image-signing integrity
Review audit logs

Monthly

Perform full registry security assessment
Review IAM assignments
Validate replication
Test image restore procedures
Audit registry compliance

Quarterly

Test disaster recovery
Rotate credentials and signing keys
Review supply chain maturity
Conduct registry penetration testing
Review incident response procedures

Runbook Summary

This runbook provides a complete enterprise methodology for assessing the security of container registries supporting Kubernetes workloads.

It evaluates every critical control across the container image lifecycle, including repository governance, identity and access management, registry encryption, vulnerability scanning, image signing, lifecycle management, monitoring, audit logging, replication, backup, disaster recovery, and Kubernetes integration.

By following this assessment process, organisations can ensure that only trusted, verified, and properly governed container images are stored, managed, and distributed to Kubernetes environments, significantly reducing the risk of software supply chain attacks and strengthening overall cloud-native security.

What’s Next?

Next Runbook: Runbook 03 — Kubernetes Software Supply Chain Security Assessment

In the next runbook, you will perform an end-to-end enterprise assessment of the Kubernetes software supply chain, covering source-code governance, CI/CD security, dependency management, build provenance, SBOMs, image signing, artifact integrity, admission control, deployment validation, runtime protection, and alignment with SLSA and NIST Secure Software Development Framework (SSDF).