1. Introduction
The VMware vCenter REST API Data Collection vulnerability allows unrestricted data collection from a VMware vCenter instance via its REST API. This could allow an attacker to gather sensitive information about the virtual infrastructure, potentially leading to further compromise. Systems running VMware vCenter are usually affected. A successful exploit may result in confidentiality loss of host data.
2. Technical Explanation
This vulnerability occurs because the vCenter REST API does not adequately restrict access to its data collection endpoints. An attacker with network access can query these endpoints without authentication, retrieving detailed information about the connected vSphere hosts. There is no known CVE associated with this specific issue as it’s often identified through configuration analysis rather than a direct code flaw. An example exploit involves an attacker using curl or similar tools to directly request data from the API.
- Root cause: Insufficient access controls on the vCenter REST API endpoints allowing unauthenticated data collection.
- Exploit mechanism: An attacker sends HTTP requests to the vCenter REST API to retrieve host information. For example, using curl to query specific API paths.
- Scope: VMware vCenter versions are affected, though specific versions haven’t been publicly documented as uniquely vulnerable; it depends on configuration and access controls.
3. Detection and Assessment
Confirming vulnerability involves checking for open API endpoints and the ability to retrieve data without authentication. A quick check is to attempt a simple query, while thorough assessment requires reviewing API access logs.
- Quick checks: Use curl or similar tools against your vCenter instance’s REST API endpoint (typically HTTPS://
/api/) and see if data is returned without credentials. - Scanning: Nessus plugin ID 16783 may identify this issue as a potential information disclosure vulnerability, but results should be verified manually.
- Logs and evidence: Review vCenter logs for API access attempts from unexpected sources or unauthenticated requests. Look for patterns of data retrieval activity.
curl -k https://your_vcenter_ip/api/versions4. Solution / Remediation Steps
Fixing this issue requires restricting access to the vCenter REST API and implementing authentication for all requests. These steps should be performed during a maintenance window.
4.1 Preparation
- Ensure you have access to the vCenter management interface and appropriate administrative privileges. A roll back plan involves restoring from the pre-change snapshot.
- A change window should be scheduled with approval from the infrastructure team.
4.2 Implementation
- Step 1: Enable authentication for all REST API requests within the vCenter configuration. This is usually found under Security settings.
- Step 2: Restrict access to the REST API to only authorized IP addresses or networks using firewall rules and vCenter’s network configuration.
- Step 3: Review user permissions and ensure that users only have the necessary level of access to perform their duties.
4.3 Config or Code Example
Before
# API Access: Unrestricted (Default)After
# API Access: Authentication Required, Restricted IP Addresses Only. Allow only 192.168.1.0/24 network.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 – limit user access to the minimum required for their role to reduce potential impact if an account is compromised.
- Practice 2: Network segmentation – restrict network access to vCenter and its API endpoints to only trusted sources.
4.5 Automation (Optional)
# Example PowerShell Script to check API access restrictions (requires vCenter PowerCLI module)
# This is an example only - adapt for your environment!
# Get-VcenterServer | Select-Object Name, ApiAccessMode
5. Verification / Validation
Confirm the fix by attempting to retrieve data from the API without authentication and verifying that access is denied. A smoke test should confirm normal vCenter functionality.
- Post-fix check: Use curl against your vCenter instance’s REST API endpoint (HTTPS://
/api/) and verify you receive an authentication error message. - Re-test: Repeat the initial quick check to confirm that data is no longer accessible without credentials.
- Smoke test: Verify users can still log in, manage VMs, and perform other core vCenter functions.
- Monitoring: Monitor vCenter logs for failed API access attempts from unauthorized sources as an indicator of potential attacks.
curl -k https://your_vcenter_ip/api/versions # Expected output: 401 Unauthorized or similar error message6. 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 to include a requirement for authentication on all vCenter REST API endpoints.
- Pipelines: Implement automated checks in your CI/CD pipeline to verify that API access restrictions are correctly configured during deployment.
- Asset and patch process: Regularly review the configuration of vCenter instances to ensure compliance with security policies.
7. Risks, Side Effects, and Roll Back
- Risk or side effect 2: Restricting IP addresses too narrowly could disrupt access for authorized tools. Mitigation: Carefully plan and document allowed IP ranges.
- Roll back: Restore from the pre-change snapshot, which will revert to the default API access configuration.
8. References and Resources
- Vendor advisory or bulletin: VMware Knowledge Base Article 2148937
- NVD or CVE entry: No specific CVE is associated with this configuration issue, but search for information disclosure vulnerabilities related to VMware vCenter.
- Product or platform documentation relevant to the fix: VMware vSphere Security Configuration Guide