This post explores the common pitfalls in auth and access control, and the architecture patterns that help you prevent abuse, enforce least privilege, and stay compliant.

🔑 Understanding Authentication vs. Authorization

• Authentication (AuthN): Verifying a user’s identity (e.g., password, MFA, SSO)
• Authorization (AuthZ): Defining what that identity is allowed to access (e.g., roles, scopes, policies)
• They’re often conflated—but must be handled with separate logic and controls

🚨 Common Authentication Mistakes

• Weak password policies: Short length, no lockout, no rate-limiting = brute-force heaven
• Storing passwords improperly: Always use bcrypt, scrypt, or Argon2—not SHA-256 or MD5
• Leaking tokens: Logging JWTs, exposing session IDs in URLs or client-side storage
• Missing MFA enforcement: Especially for privileged roles or admin panels
• Custom login code: Avoid reinventing auth—use proven identity providers or libraries

🔐 Common Authorization Failures

• Insecure direct object references (IDOR): Letting users access resources by guessing object IDs
• Role escalation: No server-side enforcement of roles or scopes
• Missing authorization checks: Assuming client-side logic is enough to gate access
• Overprivileged defaults: Assigning admin roles, wide scopes, or “*:*” permissions by default

These failures are often subtle—but exploited constantly. Think: horizontal privilege escalation, admin bypass, or exposed APIs.

🧱 Architecture Patterns for Secure Auth

• Use identity-as-a-service (IDaaS): Leverage providers like Auth0, Okta, or Azure AD
• JWTs with short lifetimes + refresh tokens: Balance performance with revocation capability
• OAuth2/OpenID Connect for delegated auth: Especially for external user or API access
• Session rotation on privilege change: Prevent session fixation and impersonation
• Token validation on the backend: Never trust claims without signature verification

⚖️ Designing Access Control That Works

• Role-Based Access Control (RBAC): Map roles to actions/resources—simple but inflexible
• Attribute-Based Access Control (ABAC): Use user, resource, and environment attributes to make decisions (e.g., time, IP, org ID)
• Policy-as-code (Rego, OPA): Make your access logic auditable, testable, and version-controlled
• Microservice enforcement: Each API/microservice should verify the token and check access—not just the front end

🧪 Testing Authentication & Access Control

• Automated auth tests: Unit test login flow, 2FA, token revocation, and expiration handling
• Authorization fuzzing: Try modifying user IDs, roles, or token scopes to access other users’ data
• Session hijack tests: Inspect cookies and tokens for exposure, replayability, or scope manipulation
• Abuse case testing: Validate what happens if the same user logs in from two IPs or exceeds rate limits

📣 Final Thought

Authentication is the front door. Authorization is the map of every room inside. If either is flawed, the rest of your AppSec efforts can collapse. Secure apps don’t just work—they protect what they expose, limit what users can do, and adapt when trust shifts.

Want help auditing your auth logic, evaluating IDaaS providers, or hardening your access control model? Let’s talk.