Security Audit

Database security auditor specialized in Row Level Security (RLS) enforcement, Zero-Trust database architecture, and forensic audit trails. Focuses on Supabase, Postgres, and Convex data layer security. For general application security (OWASP Top 10, auth patterns, security headers, input validation), use the security skill instead.

Quick Reference

Need	Approach
RLS enforcement	Enable on every public table; separate policies per operation
RLS performance	Index RLS columns; wrap auth.uid() in (select ...) subselect
Zero-Trust DB	Micro-segmentation, identity propagation, TLS enforcement
Supabase auth in RLS	Use (select auth.uid()) and auth.jwt(); never auth.role()
Convex auth guards	Call ctx.auth.getUserIdentity() in every public function
JIT access	Time-bound grants that expire automatically
Audit trails	Database triggers with immutable audit_log table
PGAudit	Extension for statement-level and object-level SQL auditing
Service role safety	Never use service_role key in client-side code
Views and RLS	Use security_invoker = true (Postgres 15+) to enforce RLS
Schema segmentation	Separate public, private, and audit schemas
Database compliance	RLS + audit logging + encryption satisfies multiple frameworks

Audit Protocol

Follow this sequence when performing a database security audit:

1. Attack Surface Mapping: Identify all entry points to the data layer (public APIs, internal dashboards, AI agents, cron jobs)
2. RLS Coverage Check: Query pg_tables to verify every public schema table has RLS enabled and appropriate policies
3. Policy Review: Check for logical bypasses, missing WITH CHECK clauses, overly permissive FOR ALL policies
4. Service Role Audit: Search client code for service_role key exposure; verify it only appears in server-side code
5. Function Audit: Check for security definer functions in exposed schemas and Convex functions missing auth guards
6. Access Simulation: Execute queries as anon and authenticated roles to verify enforcement
7. View Audit: Verify views use security_invoker = true or are not in exposed schemas
8. Audit Trail Verification: Confirm triggers or PGAudit capture all security-relevant operations
9. Compliance Validation: Map database controls against applicable regulatory frameworks

Security Principles

Principle	Database Application
Defense in Depth	RLS + application checks + schema segmentation
Least Privilege	Minimal GRANT per role; anon gets near-zero access
Zero Trust	Verify identity at DB level even for internal requests
Secure by Default	RLS enabled on creation; default-deny when no policy
Fail Securely	Postgres default-deny on RLS; generic error responses
Assume Breach	Design assuming attacker has a valid JWT

Anti-Patterns

Anti-Pattern	Risk
Security by obscurity (UUIDs only)	Attackers enumerate IDs via IDOR
Anon role with SELECT on sensitive tables	Public data exposure via Supabase API
RLS columns without indexes	Production performance degradation (100x+)
Frontend-only permission checks	Attackers bypass via direct API calls
Standing admin privileges	Excessive blast radius if compromised
service_role key in client-side code	Bypasses all RLS policies completely
FOR ALL policies instead of per-operation	Unintended write access through broad rule
Security definer functions in public schema	Functions callable from API, bypass RLS
Views without security_invoker	Views bypass RLS silently

Common Mistakes

Mistake	Correct Pattern
Using auth.uid() = user_id without wrapping in (select ...)	Use (select auth.uid()) = user_id so Postgres caches the result via initPlan
Using FOR ALL instead of separate per-operation policies	Create separate SELECT, INSERT, UPDATE, DELETE policies for clarity and safety
Leaving anon role with SELECT on sensitive tables	Restrict anon access; require authenticated role for sensitive data
Relying on UUIDs as the only access control	Enforce RLS policies and explicit auth checks alongside unique identifiers
No index on columns used in RLS USING clauses	Add B-tree indexes on all columns referenced in RLS policy expressions
Convex function missing ctx.auth.getUserIdentity() call	Every public query and mutation must validate identity before accessing data
Using service_role key in client-side code	Use anon key client-side; service_role only in server-side functions
Views bypassing RLS without security_invoker	Set security_invoker = true on views in Postgres 15+
Security definer functions in exposed schemas	Place security definer functions in non-exposed schemas with search_path = ''
No audit logging for security-relevant database events	Use triggers and PGAudit to capture all data access and modifications

Relationship to Security Skill

The application-security skill covers general application security: OWASP Top 10, authentication patterns, input validation, security headers, and compliance overviews. This database-security skill complements it by focusing on database-layer concerns: RLS policy design and performance, Supabase/Postgres-specific patterns, Convex auth guards, PGAudit configuration, and database-specific compliance implementations (SQL functions for GDPR erasure, HIPAA PHI audit triggers, etc.).

Delegation

• Verify RLS enforcement with access simulations: Use Task agent to run anonymous and authenticated queries against every public table
• Audit Convex functions for missing auth guards: Use Explore agent to scan all query and mutation handlers for getUserIdentity calls
• Design zero-trust database architecture: Use Plan agent to map schemas, access policies, JIT grants, and audit log design
• Generate database compliance evidence: Use Task agent to run audit queries and produce compliance reports

References

• rls-performance.md -- RLS policy performance, initPlan caching, stable functions, separate policies, EXPLAIN benchmarking
• zero-trust-database.md -- Micro-segmentation, identity propagation, connection security, JIT access controls
• audit-logging.md -- Trigger-based auditing, PGAudit extension and log classes, log integrity, tamper-proof storage
• convex-security.md -- Identity validation, manual RLS in functions, granular functions, role-based access via JWT claims
• threat-modeling.md -- STRIDE applied to database access, RLS bypass vectors, data layer trust boundaries
• application-security.md -- Service role management, schema exposure, security definer functions, views and RLS
• compliance-frameworks.md -- Database-specific GDPR, HIPAA, SOC2, PCI-DSS requirements and SQL implementations