Protecting ESXi hosts is crucial to ensure the confidentiality, integrity, and availability of virtualized environments, preventing data breaches, downtime, and regulatory non-compliance. With administrators frequently altering configurations within your virtualized environments, how do you maintain and/or enhance your security posture? These questions are becoming increasingly critical for all IT security professionals managing VMware products. With threats constantly evolving and new challenges emerging, it’s essential to stay vigilant and proactive in your security practices.

Recently, in a security advisory, Broadcom disclosed four critical vulnerabilities that could allow attackers to bypass sandbox and hypervisor protections in all versions of VMware ESXi products, including those no longer supported. An attacker with privileged access – root or administrator – to the guest operating system within a virtual machine (VM) could exploit these vulnerabilities to gain access to the hypervisor. Given the critical role hypervisors play in enterprise environments, these vulnerabilities pose a serious risk.

Understanding the Environment

A physical host computer can operate multiple independent guest virtual machines, each isolated from one another and the host. Managed by a hypervisor like VMware ESXi, these VMs utilize the host’s physical resources.

The sandbox, a controlled and isolated environment within which VMs operate, is designed to limit the machines’ ability to interact with the host system or other VMs beyond specific, intended interactions.

Virtual Infrastructure

 

Scope of the Vulnerabilities

The vulnerabilities disclosed by Broadcom relate to flaws in USB controllers, which could allow attackers to compromise the sandbox and hypervisor protections across all versions of VMware ESXi and Cloud Foundation products. These vulnerabilities are particularly alarming because they compromise one of the core functions of VMware products: to securely isolate sensitive operations within VMs, away from the host machine.

Proactive Measures With Entrust CloudControl

Virtualization and cloud technologies have brought new capabilities to automation, time to market, and IT flexibility, but have also heightened the need for hypervisor security. Entrust CloudControl plays a key role in capturing vital data for compliance, forensics, and troubleshooting, while identifying hypervisor configuration errors in VMware vSphere for ongoing compliance.

CloudControl offers a comprehensive range of capabilities, including the ability to automatically disable USB controllers on virtual machines across all ESXi hosts. This feature could be used to mitigate all vulnerabilities described in the Security Advisory VMSA-2024-0006 by quickly removing USB controllers from all virtual machines as described in KB96682, pending the patching of all ESXi machines.

A second line of defense involves ensuring that patches addressing the vulnerabilities have been properly applied to all ESXi hosts. This time-consuming operation can also be managed by CloudControl, which ensures that these vulnerabilities have been eliminated across the entire virtual infrastructure.

Once this verification has been carried out by CloudControl, it will then be possible to reactivate the USB controllers on all virtual machines.

In the ever-changing security landscape, every component of your IT infrastructure remains susceptible to potential threats. Staying informed about the latest security challenges is crucial. Implementing proactive security measures and continuously monitoring for vulnerabilities are key to ensuring that your VMware environments remain secure, resilient, and trustworthy. Automatic monitoring and remediation tools like Entrust CloudControl can greatly improve your overall security posture.

 

Quick References: 

VMware urges emergency action to blunt hypervisor flaws • The Register

VMSA-2024-0006.1 (VMware.com)

Entrust CloudControl | Cloud Security Posture Management | Entrust