CVE-2021-3196 in ID Bravura Security Fabric
Summary
by MITRE • 06/09/2021
An issue was discovered in Hitachi ID Bravura Security Fabric 11.0.0 through 11.1.3, 12.0.0 through 12.0.2, and 12.1.0. When using federated identity management (authenticating via SAML through a third-party identity provider), an attacker can inject additional data into a signed SAML response being transmitted to the service provider (ID Bravura Security Fabric). The application successfully validates the signed values but uses the unsigned malicious values. An attacker with lower-privilege access to the application can inject the username of a high-privilege user to impersonate that user.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 06/12/2021
The vulnerability CVE-2021-3196 represents a critical authentication bypass flaw in Hitachi ID Bravura Security Fabric versions 11.0.0 through 11.1.3, 12.0.0 through 12.0.2, and 12.1.0, specifically affecting federated identity management implementations using SAML protocols. This issue stems from improper validation of SAML response data where the system accepts signed assertions but fails to properly verify the integrity of unsigned data elements that can be manipulated by attackers. The flaw exists in the authentication processing logic that validates digital signatures but then processes unsigned attributes from the SAML response, creating a trust boundary violation where malicious data can be injected without detection.
The technical implementation of this vulnerability allows attackers to exploit a classic security weakness related to signature validation and attribute processing within SAML-based identity federation. When a user authenticates through a third-party identity provider, the SAML response contains both signed and unsigned components, with the unsigned portions typically containing user attributes such as usernames, roles, and group memberships. The Hitachi ID Bravura Security Fabric correctly validates the digital signature ensuring the integrity of the signed portions but then proceeds to use unsigned values from the response, particularly the username field, which can be manipulated by attackers. This behavior aligns with CWE-347 weakness category focusing on insufficient verification of cryptographic signatures, while also demonstrating characteristics of CWE-295 related to improper certificate validation.
The operational impact of this vulnerability is severe as it enables privilege escalation attacks where low-privilege users can manipulate SAML responses to impersonate high-privilege accounts within the system. An attacker needs only basic access to the application to exploit this vulnerability, making it particularly dangerous in environments where internal users have legitimate access paths. The attack vector involves intercepting or modifying SAML responses during transmission, injecting malicious username values that bypass normal authentication checks, effectively allowing unauthorized access to sensitive resources and administrative functions. This vulnerability directly violates the principle of least privilege and can lead to complete system compromise if the impersonated accounts possess administrative rights.
Organizations affected by CVE-2021-3196 should implement immediate mitigations including applying the vendor-provided patches, implementing additional validation controls for SAML responses, and monitoring authentication logs for suspicious activity patterns. Network segmentation and monitoring of SAML traffic can help detect potential exploitation attempts, while implementing proper access controls and role-based permissions can limit the damage from successful attacks. The mitigation strategy should also include comprehensive security testing of federated identity implementations and regular vulnerability assessments to identify similar weaknesses in other identity management systems. According to ATT&CK framework, this vulnerability maps to T1566 (Phishing) and T1078 (Valid Accounts) tactics, as attackers can leverage this flaw to gain unauthorized access using legitimate authentication mechanisms. Organizations should also consider implementing additional security controls such as multi-factor authentication, session management improvements, and regular security audits of identity federation configurations to prevent similar vulnerabilities from being exploited in the future.