CVE-2017-16853 in OpenSAML
Summary
by MITRE
The DynamicMetadataProvider class in saml/saml2/metadata/impl/DynamicMetadataProvider.cpp in OpenSAML-C in OpenSAML before 2.6.1 fails to properly configure itself with the MetadataFilter plugins and does not perform critical security checks such as signature verification, enforcement of validity periods, and other checks specific to deployments, aka CPPOST-105.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 01/10/2023
The vulnerability identified as CVE-2017-16853 resides within the DynamicMetadataProvider component of OpenSAML-C, a critical library used for implementing Security Assertion Markup Language 2.0 identity federation protocols. This flaw affects versions prior to 2.6.1 and represents a significant security weakness in the metadata handling mechanism that underpins SAML-based single sign-on implementations. The vulnerability stems from inadequate configuration of MetadataFilter plugins, which are essential for validating and processing metadata from identity providers and service providers within federated identity environments.
The technical flaw manifests in the DynamicMetadataProvider class's failure to execute essential security validation procedures that should occur during metadata processing. Specifically, the implementation does not perform signature verification of metadata sources, which is fundamental to ensuring that metadata originates from legitimate and trusted entities. Additionally, the system fails to enforce validity periods for metadata, allowing potentially expired or malicious metadata to be processed without proper time-based validation. This absence of critical security checks creates an attack surface where adversaries could inject compromised metadata into the federation, potentially leading to unauthorized access or identity spoofing attacks.
The operational impact of this vulnerability extends beyond simple authentication failures, as it fundamentally compromises the trust model that SAML-based federations rely upon. When metadata is not properly validated, the entire federation ecosystem becomes vulnerable to man-in-the-middle attacks, where malicious actors could substitute their own metadata for legitimate identity provider information. This weakness directly violates the principles of integrity and authenticity that are core to SAML security protocols and can result in unauthorized access to protected resources across multiple systems that depend on the compromised federation. The vulnerability is particularly dangerous in enterprise environments where SAML is commonly used for single sign-on across multiple applications and services.
Security professionals should recognize this vulnerability as a critical configuration management failure that aligns with CWE-254, which addresses security weaknesses in the implementation of security features. The flaw also maps to ATT&CK technique T1556.001, which involves credential access through the manipulation of authentication processes, as compromised metadata could effectively bypass authentication mechanisms. Organizations should prioritize immediate patching to version 2.6.1 or later, as this vulnerability directly impacts the security posture of any system relying on OpenSAML-C for SAML metadata processing. Additional mitigations include implementing network-level monitoring for suspicious metadata exchanges, deploying additional validation layers outside the OpenSAML library, and ensuring that all metadata sources are properly authenticated through external verification mechanisms. The vulnerability demonstrates the critical importance of proper security validation in identity federation systems and highlights the need for comprehensive testing of security controls in complex identity management infrastructures.