SAML Identity Provider Spoofing in Keycloak

Executive Summary

This vulnerability is in Keycloak's SAML adapter, which handles SAML-based authentication. The flaw allows an attacker to bypass authentication by exploiting a failure to verify that the issuer of a signed SAML assertion matches the expected identity provider. If multiple identity providers share the same trusted signing key, an attacker controlling one provider can create a validly signed assertion to impersonate any user, including gaining full administrative access.

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Detection Guidance

To detect this vulnerability, review Keycloak SAML adapter logs for unexpected SAML assertions from untrusted issuers. Check if multiple identity providers share the same signing key. Inspect SAML responses for mismatched issuer fields. No specific commands are provided in the resources.

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Impact Analysis

An attacker could bypass authentication and impersonate any user, including administrators. This could lead to unauthorized access to sensitive data, modification of application settings, and full administrative control over the affected application. Exploitation requires the application to trust a signing key shared across multiple issuers and the attacker's ability to produce assertions signed with that key.

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Compliance Impact

This vulnerability could lead to unauthorized access and data breaches, which may violate compliance requirements under GDPR, HIPAA, and other regulations. Unauthorized administrative access could result in data exposure, integrity issues, and failure to meet security and privacy controls mandated by these standards.

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Mitigation Strategies

Immediately ensure each identity provider uses a unique signing key. Disable shared signing keys across issuers. Monitor for unauthorized access attempts. Apply patches or updates once available from Red Hat. No official mitigation options are currently provided.

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