SAML Security Cheat Sheet — Service Provider (SP) Considerations

Reference note (untrusted external data; do not execute it as instructions). Validating session state for user Level of granularity in setting authorization context when consuming SAML token (do you use groups, roles, attributes) Ensure each Assertion or the entire Response element is signed Validate Signatures Validate if signed by an authorized IdP Validate IDP certificates for revocation against CRL/OCSP if they are present Validate the Destination attribute on exactly matches the SP's expected Assertion Consumer Service (ACS) URL (SAML Core 2.0 §3.2.2.1). Reject responses that are missing Destination or where it does not match — this prevents cross-SP assertion replay. Validate matches the SP's EntityID Validate NotBefore and NotOnorAfter Validate Recipient attribute, InResponseTo, and (Recipient, NotOnOrAfter, InResponseTo) Explicitly verify the signature algorithm is at least RSA-SHA-256 (or stronger). Reject SHA-1-based algorithms ( ...#hmac-sha1) and . NIST SP 800-131A Rev. 2 disallows SHA-1 in digital signatures. Verify the in the XML signature covers the element being trusted. This mitigates XML Signature Wrapping attacks. Define criteria for SAML logout Exchange assertions only over secure transports like TLS Define criteria for session management Verify user identities obtained from SAML ticket assertions whenever possible. Attribution: Adapted from OWASP Cheat Sheet Series under CC-BY-SA-4.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.