CVE-2018-8019 in Tomcat Native
Summary
by MITRE
When using an OCSP responder Apache Tomcat Native 1.2.0 to 1.2.16 and 1.1.23 to 1.1.34 did not correctly handle invalid responses. This allowed for revoked client certificates to be incorrectly identified. It was therefore possible for users to authenticate with revoked certificates when using mutual TLS. Users not using OCSP checks are not affected by this vulnerability.
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Analysis
by VulDB Data Team • 04/28/2023
The vulnerability identified as CVE-2018-8019 affects Apache Tomcat Native components version 1.2.0 through 1.2.16 and 1.1.23 through 1.1.34, specifically impacting the Online Certificate Status Protocol (OCSP) responder implementation. This flaw represents a critical weakness in the certificate validation process that undermines the security of mutual Transport Layer Security (TLS) authentication mechanisms. The issue stems from improper handling of invalid OCSP responses, creating a scenario where the system fails to properly validate certificate revocation status. The vulnerability falls under CWE-295 which specifically addresses improper certificate validation, and aligns with ATT&CK technique T1552.001 related to credentials from password storage providers, as it enables unauthorized authentication through compromised certificates.
The technical flaw manifests when the OCSP responder encounters invalid responses from certificate authorities, rather than properly rejecting these malformed or unauthorized responses. This misconfiguration allows revoked client certificates to be accepted as valid during mutual TLS authentication processes, effectively bypassing the intended certificate revocation checks. The vulnerability creates a trust boundary violation where the system incorrectly validates certificate status, enabling attackers to maintain access with certificates that should have been revoked due to compromise, expiration, or other security concerns. The improper handling occurs at the protocol level where the responder should have implemented strict validation controls but instead permitted certificate validation to proceed despite invalid OCSP responses.
The operational impact of this vulnerability is significant for organizations relying on mutual TLS authentication with certificate-based access controls. Attackers who obtain revoked client certificates can continue to authenticate and access protected systems, potentially leading to unauthorized data access, privilege escalation, and persistent access to sensitive resources. This vulnerability undermines the fundamental security principle of certificate-based authentication, where certificate revocation lists and OCSP responses serve as critical mechanisms for maintaining trust in the authentication process. Organizations using mutual TLS with OCSP validation are particularly at risk, as the vulnerability directly enables credential reuse attacks and bypasses standard security controls designed to prevent access with compromised certificates.
Mitigation strategies for CVE-2018-8019 should prioritize immediate patching of affected Apache Tomcat Native components to versions that properly handle OCSP responses. Organizations should implement comprehensive certificate lifecycle management processes that include regular certificate status verification and automated revocation checking. The fix involves ensuring that OCSP responders properly validate response formats and reject malformed responses rather than accepting them as valid. Security teams should also consider implementing additional monitoring controls to detect unauthorized certificate usage patterns and establish more robust certificate validation policies that include multiple verification mechanisms beyond OCSP. Organizations should review their mutual TLS configurations and ensure that certificate validation is performed consistently across all authentication points. The vulnerability highlights the importance of proper protocol implementation and validation, particularly in security-critical components where failure to validate inputs properly can lead to complete bypass of authentication controls.