How to remediate – VirtualBox Virtual Machine detection (dmidecode)

1. Introduction

VirtualBox Virtual Machine detection (dmidecode) identifies systems running as virtual machines within a VirtualBox environment. This matters because virtual machines may have different security characteristics than physical hardware, and knowing this allows you to apply appropriate security controls. Systems affected are typically servers or desktops virtualised using VirtualBox on various operating systems. A successful identification does not directly compromise confidentiality, integrity, or availability but indicates a need for configuration review.

2. Technical Explanation

The vulnerability arises from the presence of identifiable information within the system’s Desktop Management Interface (DMI) data. The dmidecode utility reveals details specific to VirtualBox virtual machines, such as manufacturer and product names. An attacker gaining network access can use this information to determine if a host is virtualised. There is no CVE associated with simply *detecting* a Virtual Machine; the risk lies in what an attacker does after identification. For example, an attacker might target known vulnerabilities specific to virtual machine environments or attempt lateral movement within a virtualised infrastructure.

• Root cause: The DMI information is not masked or altered to hide the virtualisation status.
• Exploit mechanism: An attacker uses dmidecode (or similar tools) from a network-accessible shell to identify the system as a VirtualBox VM.
• Scope: Linux, Windows and other operating systems running within VirtualBox are affected.

3. Detection and Assessment

Confirming whether a system is a VirtualBox virtual machine can be done quickly with command-line tools or by examining system information.

• Quick checks: Run dmidecode on Linux systems. Look for “Manufacturer” and “Product Name” fields indicating VirtualBox.
• Scanning: Nessus plugin ID 16879 can detect VirtualBox VMs, but results should be verified manually.
• Logs and evidence: System logs do not typically record this information directly; focus on the output of dmidecode.

dmidecode | grep -i virtualbox

4. Solution / Remediation Steps

Remediating this issue involves ensuring that the VirtualBox configuration aligns with your organisation’s security policy. This is a configuration review rather than a traditional patch.

4.1 Preparation

• Dependencies: Access to the target system via SSH or RDP. Roll back involves reverting any configuration changes made during the review.
• Change window needs and approval may be required depending on your organisation’s policies.

4.2 Implementation

1. Step 1: Review the VirtualBox VM settings for any unnecessary exposed features or default configurations.
2. Step 2: Ensure network access to the VM is restricted based on the principle of least privilege.
3. Step 3: Document the current configuration and rationale for any deviations from security best practices.

4.3 Config or Code Example

Before

# No specific network restrictions configured in VirtualBox VM settings

After

# Network adapter set to Bridged Adapter with a firewall enabled on the host OS.  Or, NAT networking with port forwarding limited to necessary services only. 

4.4 Security Practices Relevant to This Vulnerability

Several security practices directly address this vulnerability type.

• Practice 1: Least privilege network access reduces the attack surface if a VM is compromised.
• Practice 2: Secure configuration management ensures VMs are hardened according to your organisation’s standards.

4.5 Automation (Optional)

Automation for this issue is limited, as it primarily involves configuration review. However, you could use scripting to check VM settings across multiple hosts.

# Example PowerShell script snippet (requires VirtualBox management tools installed):
# Get-VM | Where-Object {$_.GuestOS -like "*VirtualBox*"} | Select Name, NetworkAdapterType
# This is a basic example and requires further development for comprehensive checking.

5. Verification / Validation

Confirming the fix involves re-running the detection methods to ensure that the DMI information is still revealing the VirtualBox status (which is acceptable if network access is appropriately restricted) or verifying that configurations have been updated as planned.

• Post-fix check: Run dmidecode | grep -i virtualbox again. The output should be present, but network access should be limited.
• Re-test: Re-run the initial detection method (dmidecode) to confirm it still identifies the VM as VirtualBox.
• Monitoring: Monitor network traffic for unexpected connections originating from or destined to the VM.

dmidecode | grep -i virtualbox

6. Preventive Measures and Monitoring

Preventive measures include updating security baselines and incorporating checks into your CI/CD pipelines.

• Baselines: Update your security baseline to include requirements for hardening VirtualBox VMs, such as network restrictions and secure configuration settings.
• Pipelines: Add automated checks in your deployment pipeline to verify that new VMs are configured according to the security baseline.
• Asset and patch process: Regularly review VM configurations and apply necessary updates or patches.

7. Risks, Side Effects, and Roll Back

Risks associated with this change are minimal but include potential service disruption if network access is restricted too aggressively.

• Risk or side effect 2: Incorrect configuration settings could lead to instability. Mitigation: Document all changes and have a roll back plan in place.
• Roll back: Revert any network access restrictions or configuration changes made during the review process.

8. References and Resources

Links only to sources that match this exact vulnerability. Use official advisories and trusted documentation. Do not include generic links.

• Vendor advisory or bulletin: VirtualBox Website
• NVD or CVE entry: Not applicable, as detection is the issue, not a specific vulnerability.
• Product or platform documentation relevant to the fix: VirtualBox Networking Documentation