Agentless scanning for virtual machines is a powerful security feature within Microsoft Defender for Cloud that enables comprehensive vulnerability assessment and security posture evaluation of your Azure VMs and connected cloud environments. Unlike traditional agent-based approaches that require i…Agentless scanning for virtual machines is a powerful security feature within Microsoft Defender for Cloud that enables comprehensive vulnerability assessment and security posture evaluation of your Azure VMs and connected cloud environments. Unlike traditional agent-based approaches that require installing and maintaining software on each virtual machine, agentless scanning operates by taking snapshots of VM disks and analyzing them externally.
The scanning process works by creating a temporary snapshot of the virtual machine's disk, which is then analyzed in an isolated environment managed by Microsoft. This approach provides several significant advantages. First, it eliminates the operational overhead of deploying, updating, and troubleshooting agents across your infrastructure. Second, it reduces the performance impact on production workloads since no additional software runs on the VMs themselves.
Agentless scanning can detect software vulnerabilities, installed applications, and potential security misconfigurations across Windows and Linux virtual machines. It identifies CVEs (Common Vulnerabilities and Exposures) in the operating system and installed software packages, providing detailed remediation guidance through the Defender for Cloud portal.
The feature supports multi-cloud scenarios, extending coverage to AWS EC2 instances and GCP virtual machines when properly connected to Defender for Cloud. This unified approach allows security teams to maintain consistent visibility across hybrid and multi-cloud environments.
To enable agentless scanning, you need Defender for Servers Plan 2 or Defender CSPM enabled on your subscription. The scanning occurs periodically, typically every 24 hours, ensuring your security posture remains current. Results are integrated into the Defender for Cloud recommendations and can feed into Microsoft Sentinel for advanced threat detection and security orchestration.
Agentless scanning complements rather than replaces agent-based protection, as real-time threat detection and advanced features still benefit from the Defender for Endpoint agent deployment on critical workloads.
Agentless Scanning for Virtual Machines in Azure
Why Agentless Scanning is Important
Agentless scanning for virtual machines is a critical security capability in Microsoft Defender for Cloud that enables organizations to assess vulnerabilities and security posture of their VMs without deploying any software agents. This approach significantly reduces operational overhead, eliminates compatibility issues, and provides comprehensive visibility across your entire VM fleet with minimal management effort.
What is Agentless Scanning?
Agentless scanning is a feature within Microsoft Defender for Cloud that performs vulnerability assessments and software inventory collection on Azure VMs and AWS EC2 instances by taking snapshots of VM disks. The scanning process analyzes these snapshots outside the running VM, meaning there is:
• No performance impact on production workloads • No need to install or maintain agents • No requirement for network connectivity from the VM • Coverage for VMs that cannot support traditional agents
How Agentless Scanning Works
The technical process involves several steps:
1. Snapshot Creation: Defender for Cloud creates a snapshot of the VM's OS disk 2. Secure Copy: The snapshot is copied to a secure, isolated environment managed by Microsoft 3. Analysis: The disk image is analyzed for vulnerabilities, installed software, and security misconfigurations 4. Results Delivery: Findings are reported back to Defender for Cloud within 24 hours 5. Cleanup: The snapshot copy is securely deleted after analysis
Key Features and Capabilities
• Vulnerability Assessment: Identifies OS and application vulnerabilities using Microsoft Defender Vulnerability Management • Software Inventory: Discovers installed applications, packages, and certificates • Secret Scanning: Detects plaintext secrets and credentials stored on disk • Malware Scanning: Identifies known malware signatures
Requirements and Prerequisites
• Defender for Servers Plan 2 or Defender CSPM must be enabled • Supported operating systems include Windows Server and various Linux distributions • VM disks must be unencrypted or encrypted with platform-managed keys (customer-managed keys have limitations) • Works with Azure VMs and AWS EC2 instances connected via multicloud connector
Exam Tips: Answering Questions on Agentless Scanning for VMs
Tip 1: Remember that agentless scanning requires Defender for Servers Plan 2 or Defender CSPM - Plan 1 does not include this feature.
Tip 2: Know that scans occur approximately every 24 hours and results appear in the same recommendations as agent-based assessments.
Tip 3: Understand the encryption limitations - VMs with customer-managed keys (CMK) for disk encryption may have restricted scanning capabilities.
Tip 4: Agentless scanning complements rather than replaces agent-based monitoring. For real-time protection and advanced threat detection, the Defender for Endpoint agent is still recommended.
Tip 5: When questions mention scenarios requiring security assessment of VMs that cannot have agents installed due to compliance or technical restrictions, agentless scanning is the correct answer.
Tip 6: The scanning process has no performance impact on running VMs because analysis happens on snapshot copies in an isolated environment.
Tip 7: For multicloud scenarios, remember that agentless scanning extends to AWS EC2 instances when properly connected through the multicloud connector in Defender for Cloud.