1. Introduction
The WMI Trusted Platform Module Enumeration vulnerability means information about a Trusted Platform Module on Windows systems can be accessed by connecting with valid credentials. This matters because it could allow attackers to gather details about the system’s hardware security, potentially aiding in further attacks. Systems running Windows are usually affected. A successful exploit has limited impact on confidentiality but may assist with integrity compromises and availability issues.
2. Technical Explanation
This vulnerability occurs because information about the Trusted Platform Module is accessible via Windows Management Instrumentation (WMI) when a user has sufficient permissions to connect to the remote host. An attacker can query WMI to retrieve details about the TPM, such as its version and status. There isn’t a specific CVE associated with simply enumerating this information; it’s more of an inherent risk in exposing WMI data.
- Root cause: The WMI interface exposes TPM information without strict access controls beyond standard Windows permissions.
- Exploit mechanism: An attacker connects to the target system using valid credentials and uses a WMI query to retrieve TPM details. For example, they could use PowerShell to execute
Get-WmiObject Win32_TPM. - Scope: All versions of Windows with a Trusted Platform Module are potentially affected.
3. Detection and Assessment
You can confirm if a system is vulnerable by checking for the presence of TPM information via WMI. A quick check involves listing available WMI classes, while a thorough method uses specific queries to retrieve TPM details.
- Quick checks: Run
wmic /namespace:\rootcimv2 class win32_tpm get *in Command Prompt. If the command returns data, a TPM is present. - Scanning: Nessus plugin ID 69aba7c6 can identify systems with available Trusted Platform Modules. This is an example only.
- Logs and evidence: No specific logs directly indicate this enumeration; however, successful WMI connections may be logged in the Windows Event Log under Application and Services Logs > Microsoft > Windows > Component Based Servicing.
wmic /namespace:\rootcimv2 class win32_tpm get *4. Solution / Remediation Steps
The best approach is to limit access to WMI and follow the principle of least privilege.
4.1 Preparation
- Dependencies: Ensure you have administrative privileges to modify Windows security settings. Roll back by restoring the backup or snapshot.
- Change window needs: This change requires a standard change window and approval from system owners.
4.2 Implementation
- Step 1: Review existing WMI access permissions using Group Policy or local security policies.
- Step 2: Restrict WMI access to only authorized users and groups. Use the principle of least privilege.
- Step 3: Monitor WMI event logs for unauthorized access attempts.
4.3 Config or Code Example
Before
(Default WMI permissions allowing broad access)After
(WMI permissions restricted to specific user groups with necessary access only)4.4 Security Practices Relevant to This Vulnerability
- Practice 1: Least privilege – limit user accounts and group memberships to the minimum required for their tasks, reducing the potential impact of compromised credentials.
- Practice 2: Input validation – While not directly applicable to WMI enumeration itself, validating data used in conjunction with WMI queries can prevent other attacks.
4.5 Automation (Optional)
No suitable automation script is provided as this requires careful configuration of Windows security settings.
5. Verification / Validation
Confirm the fix by attempting to enumerate TPM information with a user account that should no longer have access. Check WMI logs for denied access attempts.
- Post-fix check: Run
wmic /namespace:\rootcimv2 class win32_tpm get *as a standard user. The command should fail with an “Access Denied” error. - Re-test: Re-run the initial detection method (WMI query) using a restricted account to confirm access is denied.
- Smoke test: Verify that any legitimate applications or services relying on WMI still function correctly.
- Monitoring: Monitor Windows Event Logs for failed WMI queries from unauthorized users.
wmic /namespace:\rootcimv2 class win32_tpm get * (should return "Access Denied")6. Preventive Measures and Monitoring
- Baselines: Update security baselines to include restricted WMI access policies, such as those defined by CIS benchmarks.
- Pipelines: Integrate static analysis tools into CI/CD pipelines to identify potential WMI-related vulnerabilities in applications.
- Asset and patch process: Regularly review user permissions and group memberships on Windows systems.
7. Risks, Side Effects, and Roll Back
- Risk or side effect 2: Incorrectly configured permissions could lead to service disruptions.
- Roll back: Restore the system from backup or snapshot, or revert the Group Policy/local security policy changes.
8. References and Resources
- Vendor advisory or bulletin: No specific vendor advisory exists for this enumeration issue.
- NVD or CVE entry: No specific CVE is associated with this vulnerability.
- Product or platform documentation relevant to the fix: Microsoft Documentation on WMI Access Control.