CVE-2015-5372 in nevisAuth
Summary
by MITRE
The SAML 2.0 implementation in AdNovum nevisAuth 4.13.0.0 before 4.18.3.1, when using SAML POST-Binding, does not match all attributes of the X.509 certificate embedded in the assertion against the certificate from the identity provider (IdP), which allows remote attackers to inject arbitrary SAML assertions via a crafted certificate.
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Analysis
by VulDB Data Team • 01/04/2018
The vulnerability identified as CVE-2015-5372 represents a critical security flaw in the SAML 2.0 implementation within AdNovum nevisAuth version 4.13.0.0 and earlier. This weakness specifically manifests when the system employs SAML POST-Binding mechanisms, creating a pathway for malicious actors to exploit certificate validation processes. The issue stems from insufficient certificate attribute matching between the embedded X.509 certificate within SAML assertions and the actual identity provider certificate, fundamentally undermining the trust model that SAML is designed to establish. Such a flaw directly compromises the integrity of the authentication process, as it allows unauthorized parties to manipulate authentication assertions through carefully crafted certificates that bypass proper validation checks.
The technical implementation of this vulnerability involves the failure to perform comprehensive certificate attribute verification during SAML assertion processing. When a SAML assertion is received through POST-Binding, the system should validate that all critical attributes of the embedded certificate match those of the identity provider's certificate. However, the nevisAuth implementation only validates a subset of certificate attributes, leaving gaps that attackers can exploit. This partial validation creates an attack surface where malicious actors can construct certificates that pass the limited validation checks while containing arbitrary assertion data, effectively allowing them to inject false authentication claims into the system.
The operational impact of CVE-2015-5372 extends beyond simple authentication bypasses, as it fundamentally undermines the security assurances that SAML-based single sign-on systems are intended to provide. Attackers who successfully exploit this vulnerability can inject arbitrary SAML assertions, potentially gaining unauthorized access to protected resources, impersonating legitimate users, or conducting privilege escalation attacks. This weakness particularly affects organizations relying on nevisAuth for identity management, as it creates a persistent threat vector that could be exploited for extended periods before detection. The vulnerability's remote exploitability means that attackers do not require physical access or insider knowledge to leverage this flaw, making it particularly dangerous in environments where external network access is common.
Organizations affected by this vulnerability should immediately implement the available patches from AdNovum, specifically upgrading to version 4.18.3.1 or later, which addresses the certificate validation issue. Additional mitigations include implementing network segmentation to limit access to SAML endpoints, monitoring SAML assertion patterns for anomalies, and establishing robust certificate management practices. From a defensive perspective, this vulnerability aligns with CWE-295, which addresses improper certificate validation, and maps to ATT&CK technique T1550.001 for legitimate credentials, as successful exploitation could lead to unauthorized access through compromised authentication tokens. Security teams should also consider implementing additional layers of authentication, such as multi-factor authentication, to reduce the impact should certificate validation fail. The vulnerability demonstrates the critical importance of comprehensive certificate validation in identity management systems and highlights the need for thorough security testing of SAML implementations to prevent similar weaknesses in other identity providers.