How to Audit VMware ESX and ESXi Servers Against the VMware Hardening Guidelines with Retina CS

Retina CS Enterprise Vulnerability Management has included advanced VMware auditing capabilities for some time, including virtual machine discovery and scanning through a cloud connection, plus the ability to scan ESX and ESXi hosts using SSH. However, in response to recent security concerns associated with SSH, VMware has disabled SSH by default in its more recent versions of ESX and ESXi. Though this measure makes VMware’s ESX/ESXi servers more secure, it also reduces Retina’s ability to audit them.

Fortunately, VMware has provided an alternative method to audit its servers: the VMware SOAP API. Versions 5.3 and above of the BeyondInsight IT Risk Management console, included with Retina CS, are able to leverage this API to audit ESX and ESXi servers.

Using VMware’s SOAP API, Retina CS can perform the vast majority of VMware’s official hardening checks for ESX and ESXi, including:

• disable-ssh: Ensure that the SSH service is not running.
• disable-dcui: Ensure that the Direct Console UI is not running, so that all configuration changes must be made through a central vCenter server.
• enable-lockdown-mode: Ensure that direct management access (not mediated through vCenter) to an ESX/ESXi system is prohibited altogether.
• verify-acceptance-levels: Ensure that unsigned VMware Installation Bundles (VIBs) are not installed on an ESX/ESXi server.
• verify-kernel-modules: Ensure that the only installed kernel modules are those that are part of VMware’s standard installation.

The remainder of this document illustrates the procedure for generating a VMware-focused Vulnerabilities Report and explains selected portions of that report.

Please note: Retina CS Enterprise Vulnerability Management is delivered as part of the BeyondInsight IT Risk Management Platform. Therefore, the screenshots and configuration instructions below will reference BeyondInsight.

Running the VMware Hardening Audits Scan Retina CS leverages the BeyondInsight platform’s results-driven reporting and analytics capabilities, which means you start by specifying what you want to accomplish. In this case, you would select the “VMware Hardening Audits” report template prior to running the scan. Note that the VWware Hardening Audits scan requires Retina scan engine 5.20.0.2846 or above.

Set Options for a VMware Hardening Audits Scan

After configuring the Scan Options, click the Start Scan button at the bottom of the page. You can monitor the scan’s progress on the Jobs page. After the report has been generated, the scan will be will be available on the Reports page.

Completed Reports Page

From here, you can download a PDF copy of the report and/or view the report in a structured document format.

VMware Hardening Report Audits Highlights The VMware Hardening Audits report includes a vulnerability summary, a job metrics description, and a vulnerabilities list that comprises the vast majority of the report.

Vulnerability Summary Page

The Vulnerability Summary Page identifies several distinct vulnerabilities for the two scanned ESXi servers, with “enable-lockdown-mode” having the highest risk level. Details for each vulnerability, along with job metrics, are displayed on subsequent pages in the report.

Job Metrics and Vulnerability Detail

On the above page, the Job Metrics summary shows that the report was run against two targets (192.168.1.10 and 192.168.1.11), while the first item in the List of Vulnerabilities shows that neither of the two targets had lockdown mode enabled. The remaining pages in the List of Vulnerabilities section further describe the vulnerabilities and the corresponding affected assets.

You can also view and browse the report online, without downloading it as a PDF, as shown below:

Vulnerabilities Report with Document Map Navigation

Summary The new VMware Security Hardening capabilities in Retina CS Enterprise Vulnerability Management greatly enhance its ability to audit VMware’s vCenter, ESX and ESXi products. Retina CS can even perform security checks against ESX and ESXi servers in the absence of SSH connectivity. As always, we will continue to expand Retina’s capabilities as new vulnerabilities arise.