CVE-2018-12436 in wolfSSL
Summary
by MITRE
wolfcrypt/src/ecc.c in wolfSSL before 3.15.1.patch allows a memory-cache side-channel attack on ECDSA signatures, aka the Return Of the Hidden Number Problem or ROHNP. To discover an ECDSA key, the attacker needs access to either the local machine or a different virtual machine on the same physical host.
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Analysis
by VulDB Data Team • 03/27/2023
The vulnerability identified as CVE-2018-12436 represents a critical memory-cache side-channel attack targeting the elliptic curve digital signature algorithm implementation within wolfSSL cryptographic library. This flaw specifically affects versions prior to 3.15.1.patch and exposes the system to what security researchers have termed the "Return Of the Hidden Number Problem" or ROHNP attack vector. The vulnerability stems from insufficient protection mechanisms in the elliptic curve cryptography implementation, particularly in the ecc.c source file where ECDSA signature operations are processed. The attack exploits timing variations and cache behavior patterns that occur during cryptographic computations, allowing adversaries to infer sensitive information about private keys through careful analysis of memory access patterns.
The technical execution of this attack relies on the fundamental principles of cache-based side-channel analysis where the attacker monitors cache hit/miss patterns during cryptographic operations. When the wolfSSL library performs ECDSA signature generation, it accesses memory locations in patterns that correlate with the secret private key bits. This vulnerability specifically targets the scalar multiplication operations within elliptic curve arithmetic where the attacker can observe variations in memory access timing. The attack requires the adversary to have either local access to the machine where the cryptographic operations occur or access to a separate virtual machine running on the same physical hardware. This constraint reflects the nature of cache-based attacks which depend on shared hardware resources and temporal correlation between operations.
The operational impact of CVE-2018-12436 extends beyond simple information disclosure, as it represents a fundamental weakness in the cryptographic implementation that could lead to complete private key recovery. The vulnerability directly violates the security assumptions underlying elliptic curve cryptography, where the private key should remain secure even when the public key and signature data are publicly available. This attack demonstrates the critical importance of implementing constant-time algorithms and proper memory access patterns in cryptographic implementations, as outlined in the CWE-1037 category for side-channel attacks. The attack vector aligns with techniques described in the MITRE ATT&CK framework under the T1059.001 technique for privilege escalation through cryptographic key compromise. Organizations using affected versions of wolfSSL face significant risk of credential compromise, certificate forgery, and authentication bypass scenarios that could affect the entire security infrastructure.
The mitigation strategy for this vulnerability requires immediate upgrading to wolfSSL version 3.15.1.patch or later, which includes proper countermeasures against cache-based side-channel attacks. These countermeasures typically involve implementing constant-time algorithms, memory access randomization, and cache flushing mechanisms during cryptographic operations. System administrators should also consider implementing additional protections such as virtual machine isolation, hardware-level security features, and monitoring for unusual memory access patterns. The vulnerability highlights the necessity of following security best practices outlined in NIST SP 800-57 and other cryptographic standards that emphasize the importance of protecting against side-channel attacks. Organizations should also conduct regular security assessments to identify similar vulnerabilities in other cryptographic implementations and ensure that all cryptographic libraries maintain appropriate side-channel resistance mechanisms.