CVE-2018-5202 in SKCertService
Summary
by MITRE
SKCertService 2.5.5 and earlier contains a vulnerability that could allow remote attacker to execute arbitrary code. This vulnerability exists due to the way .dll files are loaded by SKCertService. It allows an attacker to load a .dll of the attacker's choosing that could execute arbitrary code without the user's knowledge.
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Analysis
by VulDB Data Team • 04/23/2020
The vulnerability identified as CVE-2018-5202 affects SKCertService version 2.5.5 and earlier, representing a critical remote code execution flaw that exploits improper dynamic link library loading mechanisms. This vulnerability falls under the category of insecure library loading as classified by CWE-427, where the service fails to properly validate or restrict the loading of dynamic link libraries from untrusted sources. The flaw stems from the service's design where it loads .dll files without adequate security controls, creating an attack surface that adversaries can exploit to execute malicious code remotely. The vulnerability exists because the service does not implement proper path validation or digital signature verification when loading external libraries, allowing attackers to manipulate the loading process through various means including symbolic links, path traversal, or direct file replacement attacks.
The technical exploitation of this vulnerability occurs when an attacker places a malicious .dll file in a location that the vulnerable service will load automatically, or when the service's loading mechanism can be manipulated to reference attacker-controlled paths. This type of vulnerability is particularly dangerous because it operates at the system level, potentially allowing attackers to execute code with the privileges of the service account, which often runs with elevated permissions. The attack vector typically involves placing a malicious library in a directory that the service searches during its execution, or manipulating the system PATH environment variable to direct the service toward attacker-controlled code. This flaw directly aligns with ATT&CK technique T1106 for "Local Execution" and T1059 for "Command and Scripting Interpreter" as attackers can leverage the loaded malicious code to establish persistent access or escalate privileges.
The operational impact of CVE-2018-5202 extends beyond simple remote code execution, as it can lead to complete system compromise when the vulnerable service runs with administrative privileges. Attackers can use this vulnerability to install backdoors, steal sensitive data, or deploy additional malware without user knowledge, making detection particularly challenging. The vulnerability affects systems where SKCertService is installed and running, potentially including enterprise environments where certificate management services are commonly deployed. Organizations may experience unauthorized access to sensitive certificate stores, compromise of digital signatures, and potential data breaches. The attack is particularly insidious because it can be executed silently in the background, with no visible user interaction required from the victim. The vulnerability also impacts compliance with security standards such as NIST SP 800-53 controls, specifically those related to system and information integrity, as it allows for unauthorized code execution that bypasses normal security controls.
Mitigation strategies for CVE-2018-5202 require immediate patching of affected SKCertService installations to version 2.5.6 or later, where the vulnerable library loading mechanisms have been corrected. System administrators should also implement proper access controls and least privilege principles for the service account running SKCertService, limiting the potential damage from successful exploitation. Additional protective measures include implementing application whitelisting policies, monitoring for suspicious library loading activities, and conducting regular security assessments of certificate management services. Organizations should also consider network segmentation to limit lateral movement opportunities and implement endpoint detection and response solutions to identify unauthorized DLL loading activities. The vulnerability demonstrates the importance of secure coding practices around dynamic library loading and highlights the need for proper input validation and path resolution in service applications, aligning with security best practices outlined in OWASP Top Ten and ISO 27001 controls for information security management.