What is Virtualization-Based Security for Windows Guest Operating Systems

Virtualization-Based Security (VBS) for Windows guest operating systems is a security feature that uses hardware virtualization to create and isolate a secure region of memory from the normal operating system. This helps protect the system from a variety of threats and attacks by ensuring that sensitive data and processes are isolated from potential malicious software running on the main operating system. Here’s a detailed explanation:

Key Concepts of VBS

1. Hardware Virtualization: VBS leverages hardware virtualization features present in modern CPUs (such as Intel VT-x and AMD-V) to create isolated memory regions.
2. Secure Memory Regions: These isolated memory regions, often referred to as “virtual secure mode” (VSM), are used to run security-sensitive code and store sensitive information. This separation helps prevent unauthorized access to critical system components and data.
3. Hyper-V: VBS typically uses the Hyper-V hypervisor, even on desktop versions of Windows, to manage these secure memory regions. Hyper-V ensures that the normal operating system (referred to as the “host”) and the secure mode are isolated from each other.

Components of VBS

1. Kernel Mode Code Integrity (KMCI): KMCI ensures that all kernel mode drivers and binaries loaded into the system are signed and verified, protecting against kernel-level malware.
2. Credential Guard: Credential Guard uses VBS to protect credentials, such as NTLM password hashes and Kerberos Ticket Granting Tickets (TGT), by storing them in a VSM. This makes it significantly harder for attackers to steal these credentials using techniques like Pass-the-Hash or Pass-the-Ticket.
3. Device Guard: Device Guard utilizes VBS to enforce a whitelisted set of binaries that are allowed to run on the system. This prevents unauthorized code from executing, thereby reducing the attack surface.

Benefits of VBS

1. Enhanced Security: By isolating critical security components and sensitive data from the main OS, VBS provides an additional layer of security against sophisticated attacks.
2. Mitigation of Common Attacks: VBS helps mitigate attacks that rely on compromising the operating system kernel or stealing credentials, which are common vectors in advanced persistent threats (APTs).
3. Improved Credential Protection: With features like Credential Guard, VBS significantly enhances the protection of user and system credentials against theft and misuse.

Implementation and Requirements

1. Hardware Requirements: VBS requires modern CPUs with virtualization support (Intel VT-x or AMD-V), second-level address translation (SLAT), and specific firmware settings (such as enabling virtualization in the BIOS/UEFI).
2. Operating System Requirements: VBS is supported on Windows 10 Enterprise, Windows 11, and Windows Server 2016 and later versions.
3. Configuration: Administrators can enable VBS through Group Policy or using management tools like Microsoft Endpoint Configuration Manager. It often requires additional configuration to set up features like Credential Guard and Device Guard.

Use Cases

1. Enterprise Environments: VBS is particularly beneficial in enterprise environments where protecting sensitive data and maintaining high security standards are crucial.
2. High-Security Systems: Systems that handle sensitive information, such as financial data, healthcare records, or classified government information, can leverage VBS to enhance their security posture.
3. Virtual Desktops: In virtual desktop infrastructure (VDI) environments, VBS can help secure individual virtual machines by isolating critical security components.

By using VBS, organizations can significantly enhance the security of their Windows guest operating systems, making it more difficult for attackers to compromise these systems and access sensitive information.