CVE-2017-3736 in EAGLE (Software)
Summary
by MITRE
There is a carry propagating bug in the x86_64 Montgomery squaring procedure in OpenSSL before 1.0.2m and 1.1.0 before 1.1.0g. 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. This only affects processors that support the BMI1, BMI2 and ADX extensions like Intel Broadwell (5th generation) and later or AMD Ryzen.
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Analysis
by VulDB Data Team • 07/28/2024
The vulnerability identified as CVE-2017-3736 represents a critical flaw in OpenSSL's cryptographic implementation affecting specific x86_64 processors with advanced instruction set extensions. This issue manifests in the Montgomery squaring procedure used for elliptic curve operations, specifically impacting RSA and DSA algorithms while leaving EC algorithms unaffected. The flaw stems from a carry propagation bug that occurs during modular arithmetic operations, creating potential information leakage pathways that could compromise cryptographic security. The vulnerability is particularly significant because it affects OpenSSL versions prior to 1.0.2m and 1.1.0g, representing a substantial portion of widely deployed cryptographic libraries.
The technical nature of this vulnerability aligns with CWE-128, which addresses "Wrap or Overflow" conditions in arithmetic operations, and specifically relates to improper handling of carry propagation in low-level mathematical computations. The flaw exploits the interaction between OpenSSL's optimized assembly implementations and processor-specific instructions including BMI1, BMI2, and ADX extensions found in Intel Broadwell generation processors and later, as well as AMD Ryzen processors. These extensions accelerate certain cryptographic operations but introduce the carry propagation issue when combined with OpenSSL's Montgomery squaring algorithm implementation, creating a pathway for potential information leakage through side-channel analysis.
The operational impact of this vulnerability varies significantly across different cryptographic algorithms and usage scenarios. While RSA and DSA attacks are considered extremely difficult to execute due to the complexity and resource requirements, Diffie-Hellman attacks present a more feasible threat vector. The attack feasibility for DH algorithms stems from the fact that much of the computational work required to deduce private key information can be performed offline, making the attack more practical than previously thought. This vulnerability particularly affects systems using persistent DH parameters where a single private key serves multiple clients, creating a scenario where an attacker with online access to an unpatched system could potentially compromise the private key through repeated interactions.
Mitigation strategies for CVE-2017-3736 require immediate patching of OpenSSL implementations to versions 1.0.2m or 1.1.0g and later, which address the carry propagation issue in the Montgomery squaring procedure. Organizations should prioritize updating their OpenSSL installations across all systems handling cryptographic operations, particularly those using DH key exchange with persistent parameters. Additional protective measures include monitoring for unusual cryptographic operation patterns, implementing proper key rotation protocols, and ensuring that systems using vulnerable OpenSSL versions are isolated from potential attackers. The vulnerability's requirement for specific processor architectures means that systems not utilizing Intel Broadwell or AMD Ryzen processors are not affected, though organizations should still verify their OpenSSL implementations against this and similar vulnerabilities. Security teams should also consider implementing cryptographic protocol monitoring to detect potential exploitation attempts and maintain awareness of emerging attack vectors targeting similar carry propagation issues in cryptographic libraries.