CVE-2008-4050 in PPPoE Client
Summary
by MITRE
A certain ActiveX control in fwRemoteCfg.dll 3.3.3.1 in Friendly Technologies FriendlyPPPoE Client 3.0.0.57 allows remote attackers to (1) create and read arbitrary registry values via the RegistryValue method, and (2) read arbitrary files via the GetTextFile method.
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Analysis
by VulDB Data Team • 04/06/2025
The vulnerability identified as CVE-2008-4050 represents a critical security flaw in the FriendlyPPPoE Client software version 3.0.0.57, specifically within the fwRemoteCfg.dll ActiveX control version 3.3.3.1. This issue stems from improper input validation and inadequate access controls within the ActiveX component, which exposes the system to remote exploitation through browser-based attacks. The vulnerability exists due to the lack of proper sanitization of user-supplied input passed to registry and file operations, creating a pathway for malicious actors to manipulate system resources remotely.
The technical implementation of this vulnerability manifests through two primary attack vectors that leverage the ActiveX control's exposed methods. The RegistryValue method allows attackers to create and read arbitrary registry values, effectively bypassing normal access controls and potentially enabling privilege escalation or persistent backdoor establishment. This method operates without proper validation of registry key paths or value names, permitting attackers to write to sensitive system locations or read confidential registry entries that should remain protected. The GetTextFile method presents an equally dangerous capability by enabling arbitrary file reading, allowing attackers to access files on the target system that they would normally not have permission to read, including system configuration files, user data, or sensitive application files.
The operational impact of this vulnerability extends beyond simple information disclosure to encompass potential system compromise and privilege escalation. Remote attackers can leverage these capabilities to gather sensitive information from the registry, potentially discovering system configurations, user credentials, or application-specific data that could facilitate further attacks. The ability to read arbitrary files creates opportunities for attackers to obtain system files, configuration data, or even user documents, depending on the target system's file structure and permissions. This vulnerability particularly affects systems where the FriendlyPPPoE Client is installed and the ActiveX control is enabled in web browsers, creating an attack surface that can be exploited through web-based delivery mechanisms.
Security professionals should recognize this vulnerability as a classic example of improper input validation and privilege escalation through ActiveX controls, aligning with CWE-20 for improper input validation and CWE-264 for permissions, privileges, and access controls. The attack pattern follows typical remote code execution and information disclosure vectors described in the MITRE ATT&CK framework under techniques such as T1059 for command and scripting interpreter and T1068 for exploit for privilege escalation. Organizations should implement immediate mitigations including disabling ActiveX controls in web browsers, removing vulnerable software installations, and applying appropriate network segmentation to limit potential attack surface. Additionally, regular security assessments should verify that no other ActiveX controls exist with similar vulnerabilities, and that proper access controls are implemented to prevent unauthorized registry and file operations.
The vulnerability demonstrates the inherent risks associated with ActiveX controls in enterprise environments, where legacy software components can create persistent security weaknesses. Modern security practices recommend eliminating ActiveX dependencies and transitioning to more secure, standardized web technologies that do not expose system-level functionality to remote users. System administrators should also consider implementing application whitelisting policies and monitoring for unauthorized registry modifications or file access patterns that could indicate exploitation attempts. The long-term solution involves complete removal of vulnerable software components and adoption of secure communication protocols that do not rely on potentially dangerous legacy technologies.