1. Introduction
VMware vCenter Auto Discovery allows automatic collection of information about VMware vSphere hosts and virtual machines connected to a targeted vCenter server, using authenticated access. This is common in environments managing virtual infrastructure but presents a risk if the vCenter instance is compromised. Successful exploitation could lead to sensitive data disclosure or unauthorized control of virtual systems. A compromise impacts confidentiality, integrity, and availability.
2. Technical Explanation
The vulnerability arises from the automated collection of information about the vSphere environment. An attacker gaining access to a vulnerable system can use this discovery process to map out the infrastructure connected to the vCenter server. The primary precondition is valid credentials for accessing the targeted VMware vCenter host. There is no known CVE associated with this specific auto-discovery function, but it relies on the security of the underlying vCenter authentication and authorisation mechanisms.
- Root cause: Automated information gathering without sufficient access control checks.
- Exploit mechanism: An attacker authenticates to a vCenter server and initiates the discovery process to enumerate hosts and VMs. This can be done via the vSphere API or through management tools utilising this API.
- Scope: VMware vCenter Server instances with auto-discovery enabled are affected. Specific versions depend on the configuration of the auto-discovery feature.
3. Detection and Assessment
Confirming whether a system is vulnerable involves checking if auto-discovery is active and reviewing access controls. A quick check can identify if the service is running, while thorough assessment requires examining authentication methods.
- Quick checks: Check the vCenter Server configuration for enabled discovery features through the web UI or via the command line interface (CLI).
- Scanning: Nessus plugin ID 16879 can identify VMware vSphere versions. This is an example only and may not directly detect auto-discovery status.
- Logs and evidence: Review vCenter Server logs for events related to host discovery or API calls associated with enumeration of virtual machines. Look in /var/log/vmware/vsphere_client_virgo directory (path may vary).
# Example command placeholder:
esxcli system version -b | grep "build"
4. Solution / Remediation Steps
Fixing this issue involves reviewing and restricting access to the vCenter Server, disabling unnecessary auto-discovery features, and implementing strong authentication practices.
4.1 Preparation
- Ensure you have valid credentials for accessing the vCenter server in case of issues. Roll back by restoring the snapshot taken earlier.
- A change window may be required depending on your environment and operational procedures. Approval from a system owner is recommended.
4.2 Implementation
- Step 1: Review user accounts with access to vCenter Server and remove unnecessary permissions.
- Step 2: Disable auto-discovery features if they are not required for operational purposes. This can usually be done through the vCenter web UI under configuration settings.
- Step 3: Implement multi-factor authentication (MFA) for all user accounts with access to vCenter Server.
4.3 Config or Code Example
Before
# Auto-discovery enabled (example configuration file)
auto_discovery: true
After
# Auto-discovery disabled (example configuration file)
auto_discovery: false
4.4 Security Practices Relevant to This Vulnerability
List only practices that directly address this vulnerability type. Use neutral wording and examples instead of fixed advice. For example: least privilege, input validation, safe defaults, secure headers, patch cadence.
- Practice 1: Least privilege access control reduces the impact if an account is compromised.
- Practice 2: Multi-factor authentication adds an extra layer of security to prevent unauthorised access.
4.5 Automation (Optional)
# Example PowerShell script to disable auto-discovery (requires VMware PowerCLI module)
# Connect-VIServer -Server "your_vcenter_server" -User "administrator" -Password "password"
# $vCenter = Get-VIServer | Get-VMHost
# foreach ($host in $vCenter){
# Set-VMHost -VMHost $host -AutoDiscovery false
# }
5. Verification / Validation
Confirm the fix by checking that auto-discovery is disabled and verifying access controls are correctly configured.
- Post-fix check: Check vCenter Server configuration through the web UI to confirm auto-discovery features are disabled.
- Re-test: Re-run the initial discovery process (e.g., using a management tool) to verify that it no longer enumerates hosts and VMs.
- Smoke test: Verify that core virtual machine operations, such as powering on/off VMs, still function correctly.
- Monitoring: Monitor vCenter Server logs for failed authentication attempts or unexpected API calls related to host discovery.
# Post-fix command and expected output
esxcli system version -b | grep "build" # Should not show any auto-discovery processes running
6. Preventive Measures and Monitoring
Suggest only measures that are relevant to the vulnerability type. Use “for example” to keep advice conditional, not prescriptive.
- Baselines: Update your security baseline or policy to include requirements for least privilege access control and MFA on vCenter Server.
- Pipelines: Integrate static code analysis (SCA) into CI/CD pipelines to identify insecure configurations in infrastructure-as-code templates.
- Asset and patch process: Implement a regular review cycle for user accounts and permissions on critical systems like vCenter Server.
7. Risks, Side Effects, and Roll Back
- Risk or side effect 1: Disabling auto-discovery may impact automated monitoring tools that rely on it. Mitigate by adjusting tool configurations.
8. References and Resources
- Vendor advisory or bulletin: VMware Security Advisories
- NVD or CVE entry: Not applicable for this specific auto-discovery function.
- Product or platform documentation relevant to the fix: VMware vSphere Documentation