CVE-2016-9123 in go-jose
Summary
by MITRE
go-jose before 1.0.5 suffers from a CBC-HMAC integer overflow on 32-bit architectures. An integer overflow could lead to authentication bypass for CBC-HMAC encrypted ciphertexts on 32-bit architectures.
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Analysis
by VulDB Data Team • 11/22/2022
The vulnerability identified as CVE-2016-9123 affects the go-jose library version 1.0.4 and earlier, specifically targeting systems operating on 32-bit architectures. This issue represents a critical security flaw that exploits an integer overflow condition within the CBC-HMAC encryption implementation. The vulnerability manifests when processing encrypted ciphertexts that utilize CBC-HMAC authentication mechanisms, creating a scenario where the cryptographic integrity can be compromised on 32-bit platforms. The go-jose library serves as a popular implementation of javascript object signing and encryption standards, widely adopted for securing web applications and APIs through robust cryptographic operations. The flaw directly impacts the library's ability to properly validate ciphertext integrity checks, potentially allowing unauthorized parties to manipulate encrypted data without detection.
The technical root cause of this vulnerability stems from improper handling of integer arithmetic within the CBC-HMAC implementation on 32-bit systems. When processing certain ciphertexts, the library performs calculations that exceed the maximum representable value for 32-bit integers, causing an overflow that affects the authentication validation logic. This overflow condition specifically impacts the calculation of authentication tag sizes and padding lengths used in the HMAC-SHA256 operations. The vulnerability falls under the CWE-191 integer underflow/overflow category, which is classified as a fundamental flaw in arithmetic operations that can lead to unpredictable behavior and security breaches. The implementation does not properly validate input parameters or check for arithmetic overflow conditions before performing critical cryptographic operations, creating a pathway for exploitation that leverages platform-specific architectural limitations.
The operational impact of this vulnerability extends beyond simple authentication bypass to potentially enable more sophisticated attacks including ciphertext manipulation, data tampering, and unauthorized access to protected resources. Attackers exploiting this vulnerability on 32-bit systems can craft malicious ciphertexts that pass authentication checks despite containing unauthorized modifications, effectively undermining the entire cryptographic security model. The attack vector requires the target system to be running a 32-bit architecture and to be processing encrypted data through the vulnerable go-jose library, making it particularly concerning for legacy systems or embedded environments where 32-bit processors remain prevalent. This vulnerability aligns with ATT&CK technique T1552.001, which covers "Unsecured Credentials" through manipulation of cryptographic implementations, and represents a significant weakness in the software supply chain that affects numerous applications relying on jose-based encryption.
Organizations should immediately upgrade to go-jose version 1.0.5 or later, which includes patches addressing the integer overflow condition in CBC-HMAC operations. The fix implements proper bounds checking and arithmetic validation before performing cryptographic operations, ensuring that integer calculations remain within safe limits regardless of platform architecture. System administrators should conduct comprehensive inventory assessments to identify all applications using vulnerable versions of the library, particularly focusing on legacy systems, embedded devices, and 32-bit infrastructure. Security teams should implement monitoring for unusual authentication patterns or encryption failures that might indicate exploitation attempts, while also considering the broader implications for cryptographic libraries in their software supply chain. The vulnerability highlights the importance of thorough testing on all target architectures and demonstrates how seemingly minor implementation details can have catastrophic security consequences, reinforcing the need for robust cryptographic implementation practices that adhere to industry standards such as NIST SP 800-57 and ISO/IEC 15408.