CVE-2016-5431 in PHP JOSE Library
Summary
by MITRE
TThe PHP JOSE Library by Gree Inc. version <= 2.2.0 is vulnerable to key confusion/algorithm substitution in the JWS component resulting in bypassing the signature verification via crafted tokens.
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Analysis
by VulDB Data Team • 11/21/2023
The PHP JOSE Library developed by Gree Inc. presents a critical security vulnerability in its JWS component that enables attackers to bypass signature verification through carefully crafted tokens. This vulnerability affects versions up to and including 2.2.0, creating a significant risk for applications that rely on JSON Web Signatures for authentication and data integrity. The flaw stems from insufficient validation of cryptographic algorithm parameters within the signature verification process, allowing malicious actors to manipulate the algorithm used for verification.
The technical implementation of this vulnerability resides in the library's handling of JWS headers where the algorithm parameter is not properly validated against the expected cryptographic method. This creates a key confusion scenario where an attacker can substitute one algorithm for another, effectively bypassing the intended security controls. The vulnerability specifically manifests when the library fails to enforce strict algorithm consistency between the token's declared algorithm and the actual verification process. This weakness enables attackers to craft tokens that appear to use strong cryptographic signatures while actually employing weaker or no verification mechanisms.
From an operational perspective, this vulnerability poses severe implications for systems implementing JWT-based authentication or data integrity checks. Applications using the affected library may accept malicious tokens that have been forged using different cryptographic algorithms, potentially allowing unauthorized access to protected resources or data manipulation. The impact extends beyond simple authentication bypass to include potential data integrity compromises where attackers can modify content without detection. This vulnerability particularly affects web applications, APIs, and microservices that rely on JSON Web Tokens for secure communication and access control.
The vulnerability aligns with CWE-327, which addresses the use of weak cryptographic algorithms, and relates to ATT&CK technique T1552.001 for unsecured credentials and T1078.004 for valid accounts. Organizations utilizing this library should immediately implement mitigations including upgrading to patched versions, implementing additional validation layers, and conducting thorough security assessments of their token handling processes. The recommended approach involves enforcing strict algorithm validation, implementing proper input sanitization, and establishing comprehensive monitoring for suspicious token patterns. Additionally, security teams should consider implementing cryptographic algorithm whitelisting and regular security audits to prevent exploitation of similar vulnerabilities in other components of their infrastructure.
The broader implications of this vulnerability highlight the critical importance of proper cryptographic implementation and validation in security libraries. It demonstrates how seemingly minor flaws in cryptographic protocol handling can create substantial security risks, emphasizing the need for rigorous security testing and validation of cryptographic components in software development practices. Organizations should prioritize regular security updates and maintain awareness of known vulnerabilities in third-party libraries to prevent exploitation of similar weaknesses across their technology stack.