CVE-2017-9646 in HCDownloader
Summary
by MITRE
An Uncontrolled Search Path Element issue was discovered in Solar Controls Heating Control Downloader (HCDownloader) Version 1.0.1.15 and prior. An uncontrolled search path element has been identified, which could allow an attacker to execute arbitrary code on a target system using a malicious DLL file.
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Analysis
by VulDB Data Team • 11/07/2019
The vulnerability identified in Solar Controls Heating Control Downloader version 1.0.1.15 and prior represents a critical uncontrolled search path element flaw that fundamentally compromises system security through improper dynamic link library loading mechanisms. This issue falls under the well-documented CWE-426 category, which specifically addresses the dangerous practice of allowing external code to be loaded without proper validation or control over the search path. The HCDownloader application fails to properly validate or restrict the locations from which it loads dynamic link libraries, creating an exploitable condition that enables attackers to place malicious DLL files in directories that the application searches automatically. The vulnerability manifests when the application attempts to load required libraries without implementing proper path validation or sandboxing controls that would prevent loading code from untrusted locations.
The technical exploitation of this vulnerability relies on the principle of DLL hijacking, where an attacker places a malicious DLL with the same name as a legitimate library that the application expects to load. When the HCDownloader application executes, it searches through a predefined list of directories in a specific order, and if a malicious DLL is placed in an earlier directory of this search path, the application will load and execute the attacker-controlled code instead of the legitimate library. This technique exploits the inherent trust model of Windows applications and demonstrates how applications that do not properly implement secure library loading practices become vulnerable to code injection attacks. The vulnerability specifically affects the application's dynamic loading behavior and represents a failure to implement proper security controls during the library resolution process.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a persistent foothold within the target system that can be leveraged for further compromise. Once successfully exploited, the malicious code can perform actions ranging from data exfiltration to system reconnaissance, depending on the privileges of the user running the HCDownloader application. The vulnerability affects both individual workstations and potentially larger networked environments where heating control systems are integrated with broader building management systems. Given that the application is designed for heating control management, successful exploitation could potentially disrupt critical infrastructure operations or provide attackers with access to sensitive environmental control systems. The attack vector is particularly concerning because it requires minimal user interaction, as the vulnerability can be triggered simply by running the application, making it suitable for automated exploitation campaigns.
Mitigation strategies for this vulnerability should focus on implementing proper secure coding practices and system hardening measures. Organizations should immediately update to the latest version of HCDownloader where this vulnerability has been addressed through proper implementation of controlled search paths and secure library loading mechanisms. System administrators should implement application whitelisting policies that restrict which DLL files can be loaded by the application, and employ process monitoring to detect suspicious library loading behavior. The solution should include proper path validation that ensures libraries are loaded only from trusted, predefined directories, and implementation of the principle of least privilege when running the application. Additionally, security professionals should conduct thorough application security reviews to identify similar search path vulnerabilities in other legacy applications, as this class of vulnerability is commonly found in older software implementations that were not designed with modern security considerations in mind. This vulnerability serves as a prime example of how adherence to secure coding standards and proper input validation can prevent serious exploitation scenarios that compromise system integrity and availability.