CVE-2017-3732 in Access Manager
Summary
by MITRE
There is a carry propagating bug in the x86_64 Montgomery squaring procedure in OpenSSL 1.0.2 before 1.0.2k and 1.1.0 before 1.1.0d. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH are considered just feasible (although very difficult) because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be very significant and likely only accessible to a limited number of attackers. An attacker would additionally need online access to an unpatched system using the target private key in a scenario with persistent DH parameters and a private key that is shared between multiple clients. For example this can occur by default in OpenSSL DHE based SSL/TLS ciphersuites. Note: This issue is very similar to CVE-2015-3193 but must be treated as a separate problem.
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Analysis
by VulDB Data Team • 02/02/2023
The vulnerability described in CVE-2017-3732 represents a critical flaw in OpenSSL's cryptographic implementation that specifically affects the x86_64 Montgomery squaring procedure used in modular arithmetic operations. This bug exists in OpenSSL versions 1.0.2 prior to 1.0.2k and 1.1.0 prior to 1.1.0d, creating a carry propagation error that fundamentally compromises the mathematical correctness of certain cryptographic computations. The flaw is particularly significant because it affects the underlying mathematical operations that form the foundation of RSA and DSA signature verification and generation processes, though it does not impact elliptic curve algorithms. The vulnerability stems from improper handling of carry bits during the Montgomery multiplication algorithm implementation, which is a widely used technique for efficient modular exponentiation in public key cryptography.
The operational impact of this vulnerability extends beyond simple computational errors to represent a serious security risk for systems utilizing Diffie-Hellman key exchange mechanisms. While attacks against RSA and DSA are considered extremely difficult to execute due to the complexity and resource requirements involved, the situation is considerably more concerning for Diffie-Hellman implementations. The mathematical nature of the flaw allows for potential information leakage about private keys through carefully crafted attacks that can be partially computed offline, making this vulnerability particularly dangerous in persistent DH parameter scenarios. The attack feasibility increases significantly when systems use default OpenSSL DHE-based SSL/TLS ciphersuites where private keys are shared among multiple clients, creating a scenario where an attacker could potentially gather sufficient information to compromise the security of communications. This vulnerability operates at a fundamental level within the cryptographic library, making it particularly insidious as it can affect the entire security infrastructure of systems relying on these vulnerable OpenSSL versions.
Security researchers have noted that while the attack vectors for this vulnerability are technically feasible, they require substantial computational resources and specific conditions to be effective. The attack complexity aligns with the CWE-129 weakness classification, which deals with improper handling of buffer overflows and related mathematical errors in cryptographic implementations. The vulnerability's similarity to CVE-2015-3193 demonstrates a pattern of mathematical implementation flaws in OpenSSL's cryptographic libraries, though it represents a distinct issue requiring separate remediation efforts. Organizations using vulnerable OpenSSL versions must understand that the risk is not merely theoretical but represents a real security concern for systems employing Diffie-Hellman key exchange, particularly those with persistent parameters and shared private keys. The mitigation strategy involves immediate patching of OpenSSL installations to the affected versions, along with careful review of cryptographic configurations to ensure that systems are not inadvertently exposing themselves to this vulnerability through improper use of DHE-based ciphersuites or persistent DH parameters that could enable the attack scenarios described in the vulnerability analysis.