CVE-2018-10646 in CyberGhost
Summary
by MITRE
CyberGhost 6.5.0.3180 for Windows suffers from a SYSTEM privilege escalation vulnerability through the "CG6Service" service. This service establishes a NetNamedPipe endpoint that allows arbitrary installed applications to connect and call publicly exposed methods. The "ConnectToVpnServer" method accepts a "connectionParams" argument that provides attacker control of the OpenVPN command line. An attacker can specify a dynamic library plugin that should run for every new VPN connection attempt. This plugin will execute code in the context of the SYSTEM user.
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Analysis
by VulDB Data Team • 02/01/2020
The vulnerability identified as CVE-2018-10646 represents a critical privilege escalation flaw within CyberGhost 6.5.0.3180 for Windows operating systems. This security weakness stems from the improper implementation of the CG6Service Windows service which exposes a NetNamedPipe endpoint to the system. The service architecture allows any installed application on the system to establish connections and invoke publicly accessible methods, creating an attack surface that significantly exceeds normal operational requirements. This design flaw violates fundamental security principles by providing unnecessary access to system-level functionality without proper authentication or authorization mechanisms.
The technical exploitation of this vulnerability centers on the ConnectToVpnServer method within the exposed service interface. This method accepts a connectionParams argument that directly influences the OpenVPN command line execution process. The vulnerability occurs because the application fails to properly validate or sanitize input parameters before passing them to the underlying VPN client. Attackers can manipulate the connectionParams argument to specify custom dynamic library plugins that execute during each VPN connection attempt. This represents a classic command injection vulnerability where user-controllable input directly affects system command execution. The flaw is categorized under CWE-78 as improper neutralization of special elements used in OS commands, and also aligns with CWE-20 as improper input validation.
The operational impact of this vulnerability is severe as it enables attackers to achieve SYSTEM-level privileges through a relatively simple exploitation process. When a dynamic library plugin is specified through the vulnerable parameter, the loaded plugin executes with the same privileges as the CG6Service itself, which runs under the SYSTEM context. This privilege escalation allows attackers to bypass standard user access controls and execute arbitrary code with the highest system permissions. The attack vector is particularly dangerous because it requires no special privileges to initiate the exploitation process, making it accessible to any user with local access to the system. The vulnerability essentially creates a backdoor mechanism that can be leveraged for persistent system compromise and lateral movement within network environments.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1068 which describes the use of local privilege escalation techniques. The attack chain follows a predictable pattern where local user access leads to SYSTEM privilege escalation through service manipulation. The vulnerability also demonstrates characteristics of T1059 which involves the execution of code through command-line interfaces. Organizations should implement immediate mitigations including patching the affected CyberGhost version to 6.5.0.3180 or later, disabling the vulnerable CG6Service if not required, and implementing network monitoring to detect unusual service communication patterns. System administrators should also consider implementing application whitelisting policies to restrict which applications can connect to the vulnerable named pipe endpoint. The vulnerability highlights the importance of secure service design principles and proper input validation in system-level components, particularly those that operate with elevated privileges.