CVE-2018-6766 in TVMediaHelper
Summary
by MITRE
Swisscom TVMediaHelper 1.1.0.50 contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on the targeted system. This vulnerability exists due to the way .dll files are loaded. It allows an attacker to load a .dll of the attacker's choosing that could execute arbitrary code without the user's knowledge. The specific flaw exists within the handling of several DLLs (dwmapi.dll, PROPSYS.dll, cscapi.dll, SAMLIB.dll, netbios.dll, winhttp.dll, security.dll, ntmarta.dll, WindowsCodecs.dll, apphelp.dll) loaded by the SwisscomTVMediaHelper.exe process.
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Analysis
by VulDB Data Team • 01/17/2020
The vulnerability identified in Swisscom TVMediaHelper version 1.1.0.50 represents a critical remote code execution flaw that stems from improper dynamic link library loading mechanisms within the application. This weakness allows unauthenticated attackers to remotely compromise targeted systems by manipulating the loading sequence of specific system libraries. The vulnerability specifically affects the SwisscomTVMediaHelper.exe process which loads multiple Windows system DLLs including dwmapi.dll, PROPSYS.dll, cscapi.dll, SAMLIB.dll, netbios.dll, winhttp.dll, security.dll, ntmarta.dll, WindowsCodecs.dll, and apphelp.dll. The flaw creates a path for privilege escalation and system compromise through malicious DLL injection techniques that exploit the application's trust in system library loading processes.
This vulnerability directly maps to CWE-427 Uncontrolled Search Path Element, which occurs when an application searches for libraries in a predictable path without proper validation of the library source or integrity. The attack vector leverages the Windows DLL search order mechanism where applications first look in the current working directory before checking system directories. When SwisscomTVMediaHelper.exe loads these specific DLLs without proper path validation or digital signature verification, it creates an opportunity for attackers to place malicious DLLs in the application's working directory or other search paths. The vulnerability enables attackers to execute arbitrary code with the privileges of the user running the application, potentially leading to complete system compromise. This type of vulnerability is particularly dangerous because it operates without user interaction or awareness, making it difficult to detect and prevent through standard user education or awareness programs.
The operational impact of CVE-2018-6766 extends beyond simple code execution to encompass full system compromise and potential lateral movement within network environments. Attackers can leverage this vulnerability to establish persistent backdoors, escalate privileges, and access sensitive system resources without detection. The affected DLLs represent core Windows system components that when compromised can provide attackers with access to system-level functionality including network communication, file system operations, and user authentication mechanisms. This vulnerability aligns with several ATT&CK techniques including T1059 Command and Scripting Interpreter and T1106 Execution of Fileless Malware, where attackers can execute malicious code through legitimate system processes. The vulnerability's remote nature makes it particularly attractive to threat actors as it allows for large-scale exploitation without requiring physical access to target systems.
Mitigation strategies for this vulnerability should focus on multiple defensive layers including immediate patching of the affected software, implementation of application whitelisting policies, and strict control over DLL loading behavior. Organizations should implement the principle of least privilege by running the Swisscom TVMediaHelper application with minimal required permissions and avoid executing it with administrative privileges. The recommended approach includes disabling the loading of potentially vulnerable DLLs from non-system directories, implementing strict DLL search path controls, and monitoring for suspicious DLL loading activities. Security controls should also include regular vulnerability assessments of third-party applications, network segmentation to limit lateral movement, and endpoint detection and response solutions that can identify anomalous DLL loading patterns. Additionally, system administrators should consider disabling unnecessary Windows components and services that might contribute to the vulnerability's exploitation potential, while maintaining proper system logging and monitoring for unauthorized DLL loading activities that could indicate compromise attempts.