CVE-2021-3632 in Keycloak
Summary
by MITRE • 08/26/2022
A flaw was found in Keycloak. This vulnerability allows anyone to register a new security device or key when there is not a device already registered for any user by using the WebAuthn password-less login flow.
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Analysis
by VulDB Data Team • 10/02/2022
This vulnerability exists within the Keycloak identity and access management platform, specifically affecting the WebAuthn passwordless authentication mechanism. The flaw represents a critical security weakness that undermines the integrity of the authentication process by allowing unauthorized individuals to register new security devices or cryptographic keys for user accounts without proper authorization. The vulnerability manifests when the system fails to properly validate whether a user already possesses registered security devices, creating an avenue for malicious actors to bypass normal authentication controls and potentially gain unauthorized access to user accounts.
The technical root cause of this vulnerability lies in the insufficient validation logic within Keycloak's WebAuthn implementation. When users attempt to register new security devices through the passwordless login flow, the system should verify that no existing device is already associated with the target user account. However, the current implementation lacks proper checks that would prevent duplicate device registration or unauthorized device addition to existing accounts. This weakness enables attackers to exploit the registration flow and associate new authentication credentials with user accounts they do not control, effectively undermining the security model that relies on unique, registered devices for authentication.
The operational impact of this vulnerability is significant as it directly compromises the security of the WebAuthn authentication system. Attackers could potentially register their own security keys or devices against legitimate user accounts, allowing them to authenticate as those users or to prevent legitimate users from accessing their accounts. This creates a scenario where unauthorized individuals can effectively hijack user sessions or lock out legitimate users from their own accounts, particularly in environments where WebAuthn is used as a primary authentication method. The vulnerability is especially dangerous in enterprise environments where user account compromise could lead to broader system infiltration and data breaches.
Mitigation strategies should focus on implementing proper validation checks within the WebAuthn registration process to ensure that device registration occurs only when appropriate and authorized. Organizations should immediately update to patched versions of Keycloak that address this vulnerability, as the flaw affects the fundamental authentication mechanism of the platform. Additionally, administrators should review their WebAuthn configuration settings to ensure that proper device registration policies are enforced and that the system properly validates user identity before allowing device registration. Security monitoring should be enhanced to detect unusual device registration patterns, and organizations should consider implementing additional authentication layers to compensate for the vulnerability until full patches are deployed. This vulnerability aligns with CWE-284 Access Control Issues and could be leveraged as part of broader attack chains in the MITRE ATT&CK framework, particularly under the credential access and privilege escalation domains where unauthorized device registration could facilitate further system compromise.