1. Introduction
The VMware ESX/GSX Server detection indicates a system is running a VMware server authentication daemon, likely meaning it’s running VMware Server, ESX Server, or GSX Server. This matters because these systems are common targets for attackers seeking to compromise virtual infrastructure. Successful exploitation could lead to complete control of the host and its virtual machines. A potential impact on confidentiality, integrity, and availability is high.
2. Technical Explanation
The vulnerability stems from the presence of a VMware server authentication daemon responding on the network. This banner reveals information about the running software which can be used to target known vulnerabilities. An attacker could use this information to attempt exploitation via remote code execution or other attacks specific to the identified product and version. Preconditions include network connectivity to the affected host.
- Root cause: The daemon’s banner reveals its presence and software details.
- Exploit mechanism: An attacker scans for the VMware authentication daemon, identifies the running version, then attempts exploitation using publicly available tools or exploits. For example, an attacker could use a script to identify vulnerable versions of ESXi and attempt to exploit known vulnerabilities like CVE-2019-5544.
- Scope: VMware Server, ESX Server, GSX Server. Specific affected versions depend on the identified product.
3. Detection and Assessment
Confirming a system is vulnerable involves identifying whether the VMware authentication daemon is running. A quick check can be performed using network scanning tools. More thorough assessment requires banner grabbing or direct connection attempts.
- Quick checks: Use
nmapto scan for port 902 on the target host, which is commonly used by ESXi. - Scanning: Nessus plugin ID 138645 can detect VMware Server authentication daemon. This is an example only.
- Logs and evidence: Review network traffic logs for connections to port 902. Look for the VMware banner string in connection data.
nmap -p 902 4. Solution / Remediation Steps
Remediating this detection involves ensuring systems are patched and properly configured, or isolating them if patching is not possible. The following steps provide a guide to address the issue.
4.1 Preparation
- Ensure you have access to the latest VMware patches and updates. A roll back plan involves restoring from the pre-change snapshot.
- Changes should be scheduled during a maintenance window with appropriate approval from system owners.
4.2 Implementation
- Step 1: Identify the specific VMware product (Server, ESX Server, or GSX Server) and its version.
- Step 2: Download the latest security patch for the identified product and version from the VMware website.
- Step 3: Install the downloaded patch following VMware’s official documentation.
4.3 Config or Code Example
Before
# No specific configuration example available as this is a detection of running softwareAfter
# Verify patch installation using VMware's vSphere Client or ESXi Shell. Check the build number to confirm the latest version is installed.4.4 Security Practices Relevant to This Vulnerability
Several security practices can help prevent this issue and similar vulnerabilities. These include maintaining a current patch cadence, least privilege access control, and network segmentation.
- Practice 1: Patch management reduces the window of opportunity for attackers by applying security fixes promptly.
- Practice 2: Least privilege limits the impact if an attacker compromises a system.
4.5 Automation (Optional)
# No automation example provided due to complexity of VMware patching processes. Consider using VMware's vSphere Automation API for automated patch deployment in larger environments.5. Verification / Validation
Confirming the fix involves verifying that the latest security patch is installed and re-scanning to ensure the vulnerability is no longer detected. A smoke test should confirm core functionality remains operational.
- Post-fix check: Run
esxcli system version getand verify the build number matches the expected patched version. - Re-test: Re-run the
nmap -p 902scan to confirm the VMware banner no longer reveals a vulnerable version. - Smoke test: Verify virtual machines can still be powered on and accessed normally.
- Monitoring: Monitor system logs for any errors related to the patch installation or unexpected service behavior.
esxcli system version get6. Preventive Measures and Monitoring
Preventive measures include updating security baselines, implementing vulnerability scanning in CI/CD pipelines, and establishing a regular patch review cycle. For example, use CIS benchmarks to define secure configurations.
- Baselines: Update your VMware security baseline with the latest hardening guidelines from CIS or NIST.
- Asset and patch process: Implement a monthly patch review cycle for all VMware systems.
7. Risks, Side Effects, and Roll Back
Patching can introduce compatibility issues or service downtime. Always test patches in a non-production environment first. A roll back plan involves restoring from the pre-change snapshot.
- Risk or side effect 1: Patch installation may cause temporary service interruption.
- Risk or side effect 2: Compatibility issues with third-party applications are possible.
8. References and Resources
- Vendor advisory or bulletin: https://www.vmware.com/