Defense-in-Depth Architecture & Trust Boundaries

Threats mitigated

• T2 Tool Misuse

  Manipulation of tools, APIs, or environment access to perform unintended actions or access unauthorized resources, including exploitation of access to external systems.

• T3 Privilege Compromise

  Breaking information system boundaries through context collapse, causing unauthorized data access/leakage, or exploiting tool privileges to gain unauthorized access to systems.

• T9 Identity Spoofing & Impersonation / Agent Identity Compromise

  Impersonating trusted agents, users or services, or taking over an agent's own persistent identity and credentials, to act under a trusted identity.

• T12 Agent Communication Poisoning

  Injection of malicious data into inter-agent communication channels or using external systems for side channel communications and memory persistence.

• T13 Rogue Agents in Multi-Agent Systems

  Compromised AI agent activity outside monitoring limits or orchestration in multi-agent systems.

• T16 Insecure Inter-Agent Protocol Abuse

  Attackers abuse the trust and control semantics of agent interoperability protocols such as MCP and A2A: manipulating server responses, injecting context, publishing misleading tool descriptions or exploiting ambiguous consent flows.

OWASP AISVS coverage

The AISVS 1.01 chapters and verification requirements this control helps satisfy.

C4 Infrastructure, Configuration & Deployment Security

• C4.1.1 Level 1

  Verify that AI models execute in isolated sandboxes.

C5 Access Control & Identity for AI Components & Users

• C5.2.5 Level 2

  Verify that the policy decision point for agent authorization is isolated from the agent's execution environment.

• C5.3.1 Level 2

  Verify that shared model serving infrastructure prevents one tenant's fine-tuning, inference, or embedding operations from influencing or observing another tenant's operations.

C9 Orchestration & Agentic Security

• C9.3.5 Level 2

  Verify that components processing untrusted data are isolated from tool-calling capabilities, ensuring that compromised data processing cannot trigger unauthorized tool invocations.

• C9.3.6 Level 2

  Verify that there is architectural separation between processing of untrusted tool outputs and agent operations.

• C9.5.3 Level 2

  Verify that all access control decisions are enforced by application logic or a policy engine, never by the AI model itself.

C10 Model Context Protocol (MCP) Security

• C10.1.3 Level 2

  Verify that locally launched MCP servers run in a least-privilege sandbox with restricted file system, network, and system access.

Design phase

Architecture, threat modelling and policy decisions made before code is written. 24 tasks.

Security Architecture Design

• Design multiple security layers with independent failure modes
• Plan trust boundary definition and enforcement mechanisms
• Design network segmentation strategy with micro-segmentation
• Plan data flow mapping and security control placement
• Design cryptographic verification for all trust boundaries
• Plan identity federation and trust relationship management
• Design security zone classification and access controls
• Plan security architecture validation and testing frameworks

Trust Boundary Architecture

• Design clear separation between security zones and trust levels:
  • DMZ Zone (Public): Load balancers, reverse proxies, public APIs
  • Application Zone (Restricted): Agent orchestrators, business logic
  • Data Zone (Highly Restricted): Databases, memory stores, sensitive data
  • Management Zone (Admin Only): Monitoring, configuration, audit systems
• Plan trust relationship establishment and verification procedures
• Design trust boundary crossing protocols and security checks
• Plan trust relationship revocation and recovery mechanisms
• Design trust score calculation and adjustment algorithms
• Plan trust boundary monitoring and violation detection

Zero Trust Network Design

• Design network architecture with no implicit trust between zones
• Plan software-defined perimeters (SDP) for dynamic network access
• Design encrypted communication channels for all network traffic
• Plan network access control (NAC) with device and user authentication
• Design network monitoring and threat detection systems
• Plan network policy enforcement and violation response

Build phase

Implementation, testing and hardening while the agent is developed. 41 tasks.

Network Segmentation Implementation

• Build comprehensive network segmentation with multiple isolation layers:
  • VLAN segmentation for logical network separation
  • Software-defined networking (SDN) for programmable network policies
  • Container network policies in Kubernetes environments
  • Service mesh networking with encrypted service-to-service communication
  • Firewall rules with deny-by-default and allow-listing approaches
• Deploy micro-segmentation with granular access controls:
  • Application-level segmentation with API gateway enforcement
  • Database-level segmentation with connection pooling and access controls
  • Process-level segmentation with container and namespace isolation
  • User-level segmentation with identity-based access controls

Cryptographic Trust Implementation

• Deploy comprehensive encryption for data protection:
  • TLS 1.3 for all network communications with perfect forward secrecy
  • mTLS for service-to-service authentication and encryption
  • Application-level encryption for sensitive data processing
  • End-to-end encryption for agent communications
• Implement cryptographic verification mechanisms:
  • Digital signatures for message integrity and non-repudiation
  • Certificate-based authentication with PKI infrastructure
  • Cryptographic hashing for data integrity verification
  • Key derivation and rotation for long-term security

Identity Architecture Implementation

• Build comprehensive identity and access management:
  • SPIFFE/SPIRE for workload identity in containerized environments
  • Decentralized identifiers (DIDs) for self-sovereign agent identities
  • Verifiable credentials (VCs) for capability and authorization attestation
  • Multi-factor authentication for human and service accounts
• Deploy identity federation and trust management:
  • Cross-domain trust establishment with certificate authorities
  • Identity provider integration with standards-based protocols
  • Trust relationship monitoring and automatic revocation
  • Identity lifecycle management with automated provisioning and deprovisioning

Security Control Implementation

• Deploy intrusion detection and prevention systems (IDS/IPS):
  • Network-based detection for traffic analysis and threat identification
  • Host-based detection for system-level monitoring and protection
  • Application-level detection for API and service protection
  • AI-powered detection for advanced persistent threats (APTs)
• Implement security orchestration and automated response (SOAR):
  • Automated threat response and containment procedures
  • Security playbook execution and workflow automation
  • Incident escalation and notification systems
  • Forensic data collection and evidence preservation

Operations phase

Monitoring, response and continuous improvement once the agent is live. 28 tasks.

Defense-in-Depth Operations

• Monitor all security layers for effectiveness and performance
• Execute regular security architecture assessments and penetration testing
• Maintain security control configuration and policy management
• Deploy coordinated incident response across multiple security layers
• Execute security layer integration testing and validation
• Maintain security architecture documentation and change management
• Deploy security layer performance optimization and tuning

Trust Boundary Operations

• Monitor trust boundary crossings and access patterns
• Execute regular trust relationship validation and verification
• Maintain trust score accuracy and calibration procedures
• Deploy trust boundary violation detection and response
• Execute trust relationship audit and compliance verification
• Maintain trust boundary policy updates and exception handling
• Deploy trust recovery and remediation procedures

Network Security Operations

• Monitor network traffic patterns and anomaly detection
• Execute network segmentation effectiveness testing and validation
• Maintain network policy configuration and change management
• Deploy network intrusion detection and automated response
• Execute network performance monitoring and optimization
• Maintain network security compliance and audit procedures
• Deploy network incident response and forensics capabilities

Identity & Access Operations

• Monitor identity lifecycle and access pattern analysis
• Execute identity verification and authentication testing
• Maintain identity provider integration and federation management
• Deploy identity compromise detection and response procedures
• Execute identity audit and compliance verification
• Maintain identity policy updates and exception handling
• Deploy identity recovery and remediation procedures

Tools and frameworks

Network Security & Segmentation

• Service Mesh: Istio, Linkerd, Consul Connect for secure service communication
• Network Policies: Calico, Cilium, Antrea for Kubernetes network segmentation
• Firewalls: pfSense, OPNsense, cloud provider firewalls, next-gen firewalls
• Zero Trust Networks: Zscaler, Palo Alto Prisma, Cloudflare Access, BeyondCorp

Identity & Trust Management

• PKI Systems: OpenSSL, CFSSL, Microsoft ADCS, HashiCorp Vault PKI
• Identity Standards: SPIFFE/SPIRE, W3C DIDs, OAuth 2.0, SAML 2.0
• Service Identity: Kubernetes service accounts, AWS IAM roles, Azure managed identities
• Certificate Management: cert-manager, Let's Encrypt, Venafi, DigiCert

Encryption & Cryptography

• TLS Libraries: OpenSSL, BoringSSL, rustls, Microsoft Schannel
• Cryptographic Libraries: libsodium, Bouncy Castle, Java Cryptography Architecture
• Key Management: HashiCorp Vault, AWS KMS, Azure Key Vault, Google Cloud KMS
• Hardware Security: YubiKey, AWS CloudHSM, Azure Dedicated HSM, PKCS#11 devices

Security Monitoring & Response

• SIEM Platforms: Splunk, IBM QRadar, Azure Sentinel, Elastic Security
• Network Monitoring: Nagios, Zabbix, SolarWinds, Wireshark, ntopng
• Intrusion Detection: Suricata, Snort, OSSEC, Wazuh, Falco
• SOAR Platforms: Phantom, Demisto, IBM Resilient, Google Chronicle SOAR

Related controls

• M3 Secure Inter-Agent Communication shares T9, T12, T13, T3, T16
• M13 Secure Development Lifecycle Integration shares T2, T3, T9, T12, T13
• M15 Agent Identity & Authentication Framework shares T9, T13, T3, T12, T16
• M6 Comprehensive Security Monitoring & Auditing shares T13, T2, T3, T16

References

• Zero Trust Architecture
• Network Segmentation