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Version: v1

API A2 - Broken Authentication


What is it?

Authentication mechanisms are often implemented incorrectly, allowing attackers to compromise authentication tokens, or to exploit implementation flaws to assume other user’s identities.

Compromising a system’s ability to identify the client/user, compromises API security overall.

What are specific examples?

  • Weak authentication that does not follow industry best practices.
  • Weak API keys that are not rotated.
  • Passwords that are weak, plain text, encrypted but poorly hashed, shared, or default passwords.
  • Authentication susceptible to brute force attacks and credential stuffing.
  • Credentials and keys included in URLs.
  • Lack of access token validation (including JWT validation).
  • Unsigned or weakly signed non-expiring JWTs.
  • Unprotected APIs that are considered “internal”.


Authentication Cheat Sheet

Test case FAQs

When is this test case applicable?

  • Only for API endpoints that require authentication.

How does it work?

The endpoint is subjected to a battery of authentication related tests, that probe for common weaknesses.

What is the solution?

  • Maintain a clear inventory of your API endpoints.
  • Clearly itemize APIs that require authentication and those that don't.
  • Use industry standard libraries for authentication, token generation, and password storage. Do not build your own.
  • Use multi-factor authentication (MFA).
  • Use short-lived access tokens.
  • Use stricter rate-limiting for authentication, and implement lockout policies and weak password checks.
  • Continuously validate that your authentication mechanisms are working in pre-production and production.