CVE-2017-7966 in SoMachine HVAC
Summary
by MITRE
A DLL Hijacking vulnerability in the programming software in Schneider Electric's SoMachine HVAC v2.1.0 allows a remote attacker to execute arbitrary code on the targeted system. The vulnerability exists due to the improper loading of a DLL.
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Analysis
by VulDB Data Team • 12/26/2020
The vulnerability identified as CVE-2017-7966 represents a critical DLL hijacking flaw within Schneider Electric's SoMachine HVAC v2.1.0 software, a programming environment used for developing and configuring heating, ventilation, and air conditioning control systems. This vulnerability creates a significant security risk as it allows remote attackers to execute arbitrary code on affected systems, potentially compromising industrial control systems that rely on this software for configuration and programming tasks. The flaw specifically manifests in the improper loading of dynamic link library files, which is a well-documented security weakness that has been classified under CWE-427, indicating an uncontrolled search path issue where the software fails to properly validate or restrict the locations from which it loads dynamic libraries.
The technical implementation of this vulnerability stems from the software's failure to properly secure its dynamic library loading mechanism, which is a common pattern in Windows-based applications. When SoMachine HVAC v2.1.0 attempts to load required DLL files, it does not implement proper security measures such as explicit path resolution or digital signature validation. This behavior creates an exploitable condition where an attacker can place a malicious DLL file in a location that the software will load before it reaches legitimate system directories. The vulnerability aligns with ATT&CK technique T1059.001, which covers execution through command and scripting interpreter, as the attacker can leverage this flaw to execute arbitrary code remotely without requiring local system access. The improper loading behavior typically occurs when the application searches for DLLs in a predictable order that includes user-writable directories, creating opportunities for privilege escalation attacks.
The operational impact of this vulnerability extends beyond simple code execution, particularly in industrial environments where SoMachine HVAC software is deployed for critical infrastructure control. Attackers exploiting this vulnerability could potentially gain unauthorized access to building automation systems, manipulate HVAC configurations, or even cause physical damage to facilities by altering environmental controls. The remote nature of the attack means that threat actors do not need physical access to the target system, making it particularly dangerous in environments where industrial control systems are connected to corporate networks. This vulnerability affects the integrity and availability of industrial processes, as attackers could modify system parameters or disable critical HVAC functions, leading to potential safety hazards and operational disruptions.
Mitigation strategies for CVE-2017-7966 should focus on both immediate remediation and long-term security hardening measures. Organizations should immediately apply available patches from Schneider Electric or implement workarounds such as restricting write permissions to directories where the software loads DLLs, implementing application whitelisting policies, and monitoring for suspicious DLL loading activities. The vulnerability demonstrates the importance of secure coding practices and proper DLL loading mechanisms, which are fundamental to preventing privilege escalation attacks. Security teams should also implement network segmentation to limit access to systems running SoMachine HVAC software and establish monitoring procedures to detect potential exploitation attempts. Additionally, organizations should conduct comprehensive vulnerability assessments to identify similar issues in other industrial control system software and ensure proper security controls are in place to prevent similar vulnerabilities from being exploited in the future.