Design authorization and audit logging systems
Design Authorization and Audit Logging Systems
You are tasked with designing critical security infrastructure for internal services at a fintech company. This involves two main components: an internal authorization system and a security audit logging and monitoring system.
Part A: Internal Authorization (Access Control)
Design a system for managing permissions and access control for employees, services, and automated jobs within the organization.
Requirements
- Authorization Models: Must support common authorization models, specifically Role-Based Access Control (RBAC) and Attribute-Based Access Control (ABAC).
- Security Principles: Enforce the principle of least privilege and support separation of duties.
- Policy Enforcement Speed: Permission changes (grant/revoke) must take effect quickly across the entire fleet of services.
- Performance: Authorization checks on hot paths must have low latency.
Key Considerations
Candidates should be prepared to discuss:
- The choice between RBAC, ABAC, or a hybrid model, and the rationale behind it.
- How policies are represented, stored, and evaluated.
- Strategies for caching authorization decisions, including what to cache, cache invalidation mechanisms, and correctness guarantees.
- Handling authorization for multi-tenant environments and service-to-service interactions.
- Potential threat models, such as bypass attempts, replay attacks, confused deputy problems, and privilege escalation.
Part B: Security Audit Logging and Monitoring
Design a system to record sensitive operations and detect anomalies for security auditing and monitoring purposes.
Requirements
- Immutability: Record immutable audit events for critical actions like permission changes, data exports, and key/secret access.
- Core Capabilities: The system must provide robust ingestion/collection, durable storage, query/search functionality for investigations, and alerting for suspicious patterns.
- Performance Impact: The audit logging process must not significantly impact the main business request path.
- Integrity and Compliance: Prevent or detect log tampering (including by insiders) and support long-term retention and compliance requirements.
Key Considerations
Candidates should be prepared to discuss:
- Event schema design, idempotency, and ordering guarantees for audit events.
- Different approaches for event collection (e.g., agent, library, sidecar), including buffering and backpressure handling.
- Choices for durable storage, indexing strategies, and retention tiers.
- Primitives for alerting and anomaly detection (e.g., rules, thresholds, baselines).
- Mechanisms to ensure log integrity (e.g., Write Once Read Many (WORM) storage, hash chaining, digital signing, strict access controls).
- Operational considerations, including cost, on-call support, failure modes, and disaster recovery.
AI interview prep
Core dilemma
Balancing the stringent security requirements (least privilege, tamper-proof audit logs, rapid policy enforcement) with the need for high performance (low-latency authorization checks on hot paths, minimal impact on business logic) and operational scalability in a distributed fintech environment.
3 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
Design authorization and audit logging systems
Design Authorization and Audit Logging Systems
You are tasked with designing critical security infrastructure for internal services at a fintech company. This involves two main components: an internal authorization system and a security audit logging and monitoring system.
Part A: Internal Authorization (Access Control)
Design a system for managing permissions and access control for employees, services, and automated jobs within the organization.
Requirements
- Authorization Models: Must support common authorization models, specifically Role-Based Access Control (RBAC) and Attribute-Based Access Control (ABAC).
- Security Principles: Enforce the principle of least privilege and support separation of duties.
- Policy Enforcement Speed: Permission changes (grant/revoke) must take effect quickly across the entire fleet of services.
- Performance: Authorization checks on hot paths must have low latency.
Key Considerations
Candidates should be prepared to discuss:
- The choice between RBAC, ABAC, or a hybrid model, and the rationale behind it.
- How policies are represented, stored, and evaluated.
- Strategies for caching authorization decisions, including what to cache, cache invalidation mechanisms, and correctness guarantees.
- Handling authorization for multi-tenant environments and service-to-service interactions.
- Potential threat models, such as bypass attempts, replay attacks, confused deputy problems, and privilege escalation.
Part B: Security Audit Logging and Monitoring
Design a system to record sensitive operations and detect anomalies for security auditing and monitoring purposes.
Requirements
- Immutability: Record immutable audit events for critical actions like permission changes, data exports, and key/secret access.
- Core Capabilities: The system must provide robust ingestion/collection, durable storage, query/search functionality for investigations, and alerting for suspicious patterns.
- Performance Impact: The audit logging process must not significantly impact the main business request path.
- Integrity and Compliance: Prevent or detect log tampering (including by insiders) and support long-term retention and compliance requirements.
Key Considerations
Candidates should be prepared to discuss:
- Event schema design, idempotency, and ordering guarantees for audit events.
- Different approaches for event collection (e.g., agent, library, sidecar), including buffering and backpressure handling.
- Choices for durable storage, indexing strategies, and retention tiers.
- Primitives for alerting and anomaly detection (e.g., rules, thresholds, baselines).
- Mechanisms to ensure log integrity (e.g., Write Once Read Many (WORM) storage, hash chaining, digital signing, strict access controls).
- Operational considerations, including cost, on-call support, failure modes, and disaster recovery.