CVE-2019-10201 in KeyCloak
Summary
by MITRE
It was found that Keycloak's SAML broker, versions up to 6.0.1, did not verify missing message signatures. If an attacker modifies the SAML Response and removes the <Signature> sections, the message is still accepted, and the message can be modified. An attacker could use this flaw to impersonate other users and gain access to sensitive information.
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Analysis
by VulDB Data Team • 11/25/2023
The vulnerability identified as CVE-2019-10201 affects Keycloak's SAML broker implementation in versions up to 6.0.1, representing a critical security flaw that undermines the integrity and authenticity guarantees of SAML-based authentication flows. This issue resides within the SAML response validation mechanism, specifically targeting the signature verification process that should ensure message integrity and prevent unauthorized modifications. The vulnerability stems from insufficient validation logic that fails to properly enforce signature requirements, creating an exploitable condition where malicious actors can manipulate SAML responses without detection. This flaw directly impacts the core security assumptions of SAML-based identity federation protocols, where digital signatures serve as cryptographic proof of message authenticity and integrity.
The technical implementation of this vulnerability allows attackers to exploit a missing validation check in Keycloak's SAML broker component, specifically targeting the absence of signature verification during SAML response processing. When a SAML Response is received, the system should validate that the message contains proper cryptographic signatures and that these signatures match the content being processed. However, the vulnerable implementation fails to enforce this requirement, permitting SAML responses with removed or modified signature sections to be accepted as legitimate. This creates a scenario where an attacker can intercept a valid SAML response, strip the signature elements, modify user attributes or authentication claims, and submit the altered response to the Keycloak broker, which will process it without raising any validation flags.
The operational impact of this vulnerability extends beyond simple authentication bypasses, as it enables sophisticated impersonation attacks that can compromise entire user sessions and access control mechanisms. Attackers can leverage this flaw to assume the identity of legitimate users, potentially gaining access to sensitive information, privileged resources, and confidential data within the protected applications. The vulnerability affects the fundamental trust model of SAML-based authentication systems, where the integrity of identity assertions is paramount for maintaining secure access controls. Organizations using Keycloak as a SAML broker for identity federation are particularly at risk, as this flaw can be exploited to undermine the security posture of integrated applications and services that rely on Keycloak for authentication and authorization services.
Mitigation strategies for this vulnerability require immediate implementation of version updates to Keycloak 6.0.2 or later, which contain the necessary fixes to properly enforce SAML signature validation. Organizations should also implement additional monitoring and logging mechanisms to detect anomalous authentication patterns that might indicate exploitation attempts. Security teams should review and validate all SAML configurations to ensure proper signature requirements are enforced, and consider implementing additional cryptographic validation checks beyond the default Keycloak settings. This vulnerability aligns with CWE-347, which addresses improper verification of cryptographic signatures, and maps to ATT&CK technique T1566.002 for credential access through SAML authentication manipulation. Organizations should also conduct comprehensive security assessments of their SAML-based identity infrastructure to identify and remediate similar signature validation weaknesses that might exist in other components of their authentication ecosystem.