CVE-2016-9122 in go-jose
Summary
by MITRE
go-jose before 1.0.4 suffers from multiple signatures exploitation. The go-jose library supports messages with multiple signatures. However, when validating a signed message the API did not indicate which signature was valid, which could potentially lead to confusion. For example, users of the library might mistakenly read protected header values from an attached signature that was different from the one originally validated.
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Analysis
by VulDB Data Team • 11/22/2022
The go-jose library vulnerability CVE-2016-9122 represents a critical security flaw in cryptographic signature validation mechanisms that affects versions prior to 1.0.4. This vulnerability stems from the library's handling of multiple signatures within a single message, creating a fundamental misalignment between signature verification and header attribute access. The core issue emerges when applications process messages containing multiple signatures, where the validation API fails to clearly indicate which specific signature was successfully validated. This ambiguity creates a dangerous scenario where developers might inadvertently access header attributes from a different signature than the one that was actually verified, leading to potential security bypasses and unauthorized operations.
The technical implementation flaw resides in the library's signature validation API design, which does not provide explicit context about which signature was validated during the verification process. When a message contains multiple signatures, the system should clearly identify which signature was successfully authenticated, yet the API behavior allowed for confusion between different signature validations. This design deficiency creates a path for attackers to manipulate the signature selection process, potentially causing applications to trust header values from an unverified signature while the actual verification occurred on a different signature. The vulnerability directly maps to CWE-295 which addresses improper certificate validation and CWE-347 which covers improper validation of certificates or cryptographic signatures, as the flaw involves incorrect handling of signature verification results.
From an operational impact perspective, this vulnerability enables attackers to potentially exploit applications that rely on go-jose for cryptographic operations, particularly those involving JWT tokens or similar signed messages. The confusion between signature validation and header attribute access creates opportunities for privilege escalation attacks, where malicious actors could manipulate header values to bypass security controls or gain unauthorized access to protected resources. Applications using the affected library might incorrectly process security-relevant header fields, such as audience claims, issuer identifiers, or expiration timestamps, leading to authentication bypasses or authorization failures. This vulnerability particularly affects systems implementing token-based authentication where header attributes are critical for access control decisions, making it a significant concern for web applications, api gateways, and identity management systems.
The mitigation strategy for CVE-2016-9122 requires immediate upgrading to go-jose version 1.0.4 or later, which addresses the signature validation clarity issue through enhanced API responses that explicitly indicate which signature was validated. Organizations should also implement code reviews to ensure that applications properly handle signature validation results and do not assume that header attributes from a validated signature are automatically trustworthy. Security teams should monitor for applications using vulnerable versions of the library and conduct thorough testing to verify that signature validation behavior aligns with expected security controls. Additionally, implementing proper input validation and signature verification logging can help detect potential exploitation attempts, while following the ATT&CK framework's mitigation strategies for credential access and privilege escalation can provide additional defense layers against attackers leveraging this vulnerability.