How to remediate – Windows Network Config Enumeration

1. Introduction

Windows Network Config Enumeration gathers details about a Windows computer’s network setup. This information can help attackers map a network and identify potential targets. Systems running any version of Windows are usually affected. A successful exploit could lead to loss of confidential network data, disruption of services, or compromise of system integrity.

2. Technical Explanation

This vulnerability involves the retrieval of detailed network configuration information from a Windows system. An attacker needs local access to enumerate this data. There is no specific CVE associated with basic enumeration, but it forms part of many post-exploitation activities. For example, an attacker gaining initial access via phishing could use this to identify internal network resources.

• Root cause: The operating system allows unprivileged users to query network configuration details through standard APIs and command line tools.
• Exploit mechanism: An attacker logs onto a Windows machine and uses commands like ipconfig /all or PowerShell cmdlets to gather network information. This data is then used for reconnaissance.
• Scope: All versions of Windows are affected, as the functionality is core to the operating system.

3. Detection and Assessment

Confirming vulnerability involves checking if network configuration details can be retrieved. A quick check shows whether basic enumeration is possible. Thorough assessment looks for evidence of this activity in logs.

• Quick checks: Run ipconfig /all in a command prompt. If output is displayed, the system is vulnerable to enumeration.
• Scanning: Nessus plugin ID 10386 can identify systems where network configuration details are accessible. This is an example only.
• Logs and evidence: Check event logs for unusual activity related to network configuration queries. There are no specific event IDs, so look for patterns of repeated ipconfig or PowerShell commands.

ipconfig /all

4. Solution / Remediation Steps

Fixing this issue focuses on limiting local access and monitoring for suspicious activity. These steps reduce the risk but do not eliminate it entirely.

4.1 Preparation

• Dependencies: No specific dependencies exist. Roll back plan: Restore from backup if issues occur.
• Change window: Standard maintenance window is sufficient, with approval from IT management.

4.2 Implementation

1. Step 1: Implement least privilege access controls to limit user permissions on the system.
2. Step 2: Enable auditing of network configuration queries in event logs.
3. Step 3: Regularly review event logs for suspicious activity related to network enumeration.

4.3 Config or Code Example

Before

Local Administrator account with full permissions.

After

Standard user accounts with limited permissions, restricting access to network configuration settings.

4.4 Security Practices Relevant to This Vulnerability

Practices that directly address this vulnerability type include least privilege and regular security audits.

• Practice 1: Least privilege reduces the impact if an attacker gains local access, limiting what they can discover.

4.5 Automation (Optional)

# PowerShell example to restrict access to network configuration settings
# This is an example only and requires careful testing in your environment.
# Get-Acl "HKLM:SYSTEMCurrentControlSetServicesTcpipParameters" | Set-Acl -Access (New-Object System.Security.AccessControl.FileSystemAccessRule("Everyone","ReadAndExecute","ContainerInherit,ObjectInherit","None","Allow"))

5. Verification / Validation

Confirming the fix involves checking that network configuration details are no longer accessible to standard users. A negative test verifies restricted access.

• Post-fix check: Log in as a standard user and run ipconfig /all. The command should fail or return limited information.
• Re-test: Re-run the earlier detection (ipconfig /all) with a standard user account to confirm access is restricted.
• Smoke test: Verify that basic network connectivity still works, such as browsing websites and accessing shared resources.
• Monitoring: Look for unusual event log entries related to network configuration queries from non-administrative accounts. This is an example only.

ipconfig /all (as standard user - should fail)

6. Preventive Measures and Monitoring

Update security baselines and implement monitoring for suspicious activity.

• Baselines: Update a security baseline or policy to enforce least privilege access controls on Windows systems. For example, CIS Control 5 addresses account management.
• Pipelines: Add checks in CI/CD pipelines to ensure that new images are configured with appropriate permissions and auditing settings.
• Asset and patch process: Review system configurations regularly to identify any deviations from security baselines. A quarterly review is sensible.

7. Risks, Side Effects, and Roll Back

Restricting access may impact some applications that require network configuration information. Roll back involves restoring the original permissions.

• Roll back: Restore the original ACLs on the affected registry keys using a backup or by manually reconfiguring the permissions.

8. References and Resources

• Vendor advisory or bulletin: Microsoft Security Baselines
• NVD or CVE entry: Not applicable for basic enumeration.
• Product or platform documentation relevant to the fix: Get-Acl Documentation