Overview
CVE-2025-66265 describes a critical privilege escalation vulnerability affecting CMService.exe. This vulnerability arises from the creation of the C:\usr directory and its subdirectories with overly permissive permissions, specifically granting write access to all authenticated users. This flaw allows malicious actors with standard user accounts to potentially overwrite critical configuration files or inject malicious DLLs, ultimately leading to privilege escalation and system compromise.
Technical Details
The root cause of CVE-2025-66265 lies in the insecure default permissions assigned to the C:\usr directory and its subdirectories when created by CMService.exe. Authenticated users, even those with low privileges, can modify files within these directories. This becomes a security risk when these directories contain configuration files, such as snmp.conf, used by system services, or when they are included in DLL search paths. An attacker could replace legitimate files with malicious counterparts, leading to code execution with elevated privileges when the affected service or application is launched or when the DLL is loaded.
CVSS Analysis
Currently, the CVSS score for CVE-2025-66265 is listed as N/A. However, given the potential for privilege escalation, a thorough assessment is crucial. A high CVSS score is anticipated once the relevant metrics are fully evaluated due to the ease of exploitation by local attackers and the severe impact on system integrity.
Important Note: While the initial CVSS is N/A, organizations should treat this vulnerability with high priority due to the potential impact.
Possible Impact
Successful exploitation of CVE-2025-66265 can have severe consequences, including:
- Privilege Escalation: Attackers can gain administrative or system-level privileges, allowing them to take complete control of the affected system.
- System Compromise: With elevated privileges, attackers can install malware, steal sensitive data, modify system configurations, and disrupt critical services.
- Lateral Movement: Compromised systems can be used as a launching point to attack other systems within the network.
Mitigation and Patch Steps
The primary mitigation strategy is to apply the official patch or update provided by the vendor (Megatec). Follow these steps:
- Identify Affected Systems: Determine which systems are running the vulnerable version of
CMService.exe. - Apply the Patch: Download and install the patch from the vendor’s website (see references below). Ensure you follow the vendor’s instructions carefully.
- Verify Installation: After patching, verify that the vulnerability has been remediated. This may involve checking file versions or running vulnerability scans.
- Restrict Permissions (If Patch is Unavailable): As a temporary workaround, if a patch is not immediately available, restrict write access to the
C:\usrdirectory and its subdirectories. Only grant write permissions to the necessary system accounts. This should be done with caution and thorough testing to avoid disrupting legitimate system functionality.
