CVE-2017-15698 in Tomcat Native Connector
Summary
by MITRE
When parsing the AIA-Extension field of a client certificate, Apache Tomcat Native Connector 1.2.0 to 1.2.14 and 1.1.23 to 1.1.34 did not correctly handle fields longer than 127 bytes. The result of the parsing error was to skip the OCSP check. It was therefore possible for client certificates that should have been rejected (if the OCSP check had been made) to be accepted. Users not using OCSP checks are not affected by this vulnerability.
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Analysis
by VulDB Data Team • 02/03/2023
The vulnerability described in CVE-2017-15698 represents a critical flaw in Apache Tomcat Native Connector's handling of X.509 certificate extensions, specifically within the Authority Information Access (AIA) extension field. This issue affects versions 1.2.0 through 1.2.14 and 1.1.23 through 1.1.34 of the connector component. The flaw manifests during the parsing process of client certificates when the AIA extension field exceeds 127 bytes in length, creating a significant security gap that undermines the certificate validation process.
The technical implementation of this vulnerability stems from improper boundary checking within the certificate parsing logic. When the AIA extension field surpasses the 127-byte threshold, the parsing routine fails to correctly process the extended data, resulting in an incomplete or skipped OCSP (Online Certificate Status Protocol) validation check. This parsing error creates a scenario where the connector essentially ignores the certificate's validity status, allowing potentially compromised or revoked certificates to bypass authentication mechanisms. The issue directly relates to CWE-129, which addresses improper validation of array index bounds, and CWE-20, concerning input validation vulnerabilities that can lead to security breaches through malformed data processing.
The operational impact of this vulnerability is particularly severe in environments where certificate-based authentication relies on OCSP validation for security enforcement. Attackers could exploit this weakness by presenting client certificates with extended AIA fields that would normally trigger rejection if proper OCSP checking were performed. This creates a window of opportunity for unauthorized access to systems that depend on client certificate authentication, potentially compromising the entire security infrastructure. The vulnerability essentially undermines the trust model established by certificate authorities, allowing malicious actors to bypass authentication controls that should prevent access to sensitive resources.
Organizations using Apache Tomcat Native Connector with OCSP validation enabled face significant risk from this vulnerability, as it directly impacts the integrity of client certificate authentication mechanisms. The mitigation strategy involves upgrading to versions of the connector that have addressed this parsing flaw, typically versions beyond the affected ranges mentioned in the CVE. Additionally, system administrators should consider implementing alternative certificate validation mechanisms or strengthening overall authentication protocols to reduce reliance on potentially compromised certificate validation processes. This vulnerability aligns with ATT&CK technique T1552.001, which covers credentials in files, as it affects the certificate-based authentication system that relies on proper credential validation. The flaw demonstrates how seemingly minor parsing errors in cryptographic validation components can create substantial security weaknesses in enterprise authentication systems.