CVE-2017-2219 in Simeji
Summary
by MITRE
Untrusted search path vulnerability in the [Simeji for Windows] installer (simeji.exe) allows an attacker to gain privileges via a Trojan horse DLL in an unspecified directory.
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Analysis
by VulDB Data Team • 06/20/2020
The vulnerability identified as CVE-2017-2219 represents a critical untrusted search path issue within the Simeji for Windows installer component known as simeji.exe. This flaw resides in the installer's dynamic link library loading mechanism, which fails to properly validate the source and integrity of dynamically loaded modules during the installation process. The vulnerability manifests when the installer searches for required DLL files in a predictable sequence of directories without implementing proper security checks to verify the legitimacy of the loaded components.
The technical exploitation of this vulnerability follows a well-established pattern that aligns with common software supply chain attack vectors. When the simeji.exe installer executes, it traverses the system's PATH environment variable to locate necessary dynamic link libraries. Attackers can leverage this behavior by placing a malicious Trojan horse DLL in a directory that appears earlier in the search path than the legitimate system directories. This allows the installer to inadvertently load and execute the attacker-controlled code with the privileges of the user running the installation process. The vulnerability directly maps to CWE-426, which describes the insecure loading of dynamic libraries, and represents a classic privilege escalation vector.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to perform privilege escalation attacks that can result in full system compromise. When a user with administrative privileges executes the vulnerable installer, the malicious DLL can run with elevated permissions, potentially allowing attackers to install persistent backdoors, modify system files, or establish command and control channels. The vulnerability's exploitation is particularly concerning because it can be triggered through social engineering tactics where users unknowingly download and execute the installer from untrusted sources, making it a significant concern for enterprise environments where users may not always exercise proper security awareness. This vulnerability's characteristics align with ATT&CK technique T1059, which covers command and script interpreter execution, and T1068, which covers exploit for privilege escalation.
Mitigation strategies for CVE-2017-2219 should focus on both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities. The primary solution involves applying the vendor's official patch or update that addresses the untrusted search path issue by implementing proper DLL loading security measures such as explicit path resolution or using Windows' built-in security features like DEP (Data Execution Prevention) and ASLR (Address Space Layout Randomization). Organizations should also implement strict access controls and privilege separation to minimize the impact of potential exploitation. System administrators should consider implementing application whitelisting policies that restrict which executables can run on the system, particularly for installation packages. Additionally, regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other software components, with particular attention to any software that performs dynamic library loading without proper validation mechanisms. The vulnerability underscores the importance of secure coding practices and proper input validation in installer and setup programs, particularly those that handle dynamic library loading operations.