SAML assertion signature, audience, or response binding failure
The service provider trusts an assertion whose signature or authentication context is not valid for the receiving flow.
Candidate CWE: CWE-347 · CWE-287
Test hypothesis#
Use a local IdP/SP with two synthetic accounts. Compare a valid assertion with independently changed signed content, wrong audience/recipient, expiry, one replay, and mismatched InResponseTo where required. Trace which validated signed XML element supplies the consumed identity and attributes.
Evidence required#
Record the accepted identity, trust configuration, validation path, and the one invalid condition that survives. Keep signature failure separate from audience or response-binding failure when assigning a CWE.
Rule out false positives#
Decoding XML, modifying an unsigned irrelevant field, or using an explicitly supported IdP-initiated flow does not prove forgery. A signature check on one element does not establish that the consumed identity came from that element.
Playbook and command references#
- Authentication, recovery, federation, and session lifecycle — Test registration, recovery, identity changes, invitations, SSO enforcement, and deprovisioning as one account state machine.
- Source review: entry point to protected operation — Trace attacker control and authorization through handlers, services, queues, and sensitive operations; promote only reachable violations of a stated invariant.
- OAuth, OIDC, and SAML: transaction binding and token trust — Separate browser transaction binding, issuer trust, token purpose, and identity linking using controlled federation fixtures.
Find the associated command snippets
Referenced by these target playbooks#
Report checklist#
- Capture the affected version, configuration, identities, and object ownership.
- Preserve a valid baseline and a negative control.
- Reproduce the forbidden data access, action, or state change on controlled fixtures.
- Explain the intended security rule and why the observed behavior violates it.
- State prerequisites, uncertainty, cleanup, and the smallest demonstrated impact.
Conditional ATT&CK mapping#
No direct ATT&CK mapping selected. Record the weakness and demonstrated impact without forcing an adversary-behavior classification. See the mapping guide.