Listen to this Post
Introduction:
Microsoft Defender for Endpoint (MDE) has silently deployed a game-changing feature for security teams: dynamic asset rules for security settings management. This long-awaited update finally allows for the automated, centralized governance of unmanaged Windows, macOS, and Linux endpoints, eliminating the reliance on cumbersome manual scripts and error-prone manual tagging processes.
Learning Objectives:
- Understand the operational challenge of managing “unmanaged” endpoints and how the new dynamic asset rules solve it.
- Learn how to create and apply dynamic device groups to automate MDE security policy deployment.
- Gain practical knowledge through verified commands and configurations to implement this in your own environment.
You Should Know:
1. The Power of Dynamic Device Groups
Dynamic device groups use filter rules to automatically add and remove devices based on their properties, such as OS version, domain, or even a custom tag. This is the core of the new MDE management capability.
How to Use It:
1. Navigate to the Microsoft Defender portal (`security.microsoft.com`).
- Go to Settings > Endpoints > Device groups under Permissions.
3. Click + Add device group.
- Provide a name and description (e.g., “All Linux Production Servers”).
5. Under Membership type, select Dynamic device.
- Build your rule. For example:
(deviceOSPlatform eq "Linux") and (deviceTags contains "Production"). - Click Done and then Create. Any device matching this criteria will now be automatically added to this group.
-
Leveraging the MDE Management Tag for Policy Assignment
Once your dynamic device group is created, you can use it to apply a “Management” tag. This tag is then used as the target for your security policies, moving you away from the risky “all devices” option.
How to Use It:
- In the Defender portal, go to Settings > Endpoints > General > Advanced features.
- Ensure Microsoft Intune connection is configured for central management.
- Navigate to Settings > Endpoints > Security settings management.
- You will now see the option to apply policies to “Tagged devices”. Select this.
- The policies you configure will now only apply to devices that have been automatically tagged via your dynamic device group membership.
3. Verifying Device Tag Assignment with Advanced Hunting
It is critical to verify that your dynamic rules are working correctly. Advanced Hunting in MDE provides real-time visibility into device properties, including tags.
KQL Query for Verification:
DeviceInfo | where Tags contains "Production" | project DeviceName, OSPlatform, DeviceId, Tags | sort by DeviceName asc
How to Use It:
1. Go to Hunting > Advanced hunting.
- Paste the above KQL query into the query window.
- Click Run query. The results will show you all devices that have been successfully tagged with “Production”, allowing you to audit the effectiveness of your dynamic group rules.
4. Linux Endpoint Configuration Audit (SSH)
For Linux endpoints enrolled in MDE, you can remotely verify the applied security configurations, such as EDR state and sensor health.
SSH Command:
mdatp health --field edr_device_tags
How to Use It:
1. SSH into a Linux server under management.
- Run the command
mdatp health. This will return a full health status of the MDE sensor. - To specifically check which management tags have been applied, run
mdatp health --field edr_device_tags. The output should reflect the tags applied by your dynamic device group.
5. Windows Endpoint Policy Audit (Command Prompt)
On Windows endpoints, you can use PowerShell to check the status of security policies applied through MDE management, ensuring they have been received and are active.
PowerShell Command:
Get-MpComputerStatus | Select-Object AntivirusEnabled, AntispywareEnabled, RealTimeProtectionEnabled, IoavProtectionEnabled, BehaviorMonitorEnabled
How to Use It:
- Open PowerShell with administrative privileges on a Windows endpoint.
- Execute the `Get-MpComputerStatus` cmdlet. This returns the status of all Defender antivirus features.
- The piped `Select-Object` command filters the output to show key protection features, confirming that policies are active.
6. Automating Onboarding with a Script (Linux)
The initial onboarding of unmanaged devices can also be automated. This bash script downloads the MDE onboarding package and applies it.
Bash Script Snippet:
!/bin/bash Download the onboarding package from the MDE portal wget https://aka.ms/linux-mde-onboarding -O /tmp/mde_onnboard.sh Make it executable chmod +x /tmp/mde_onnboard.sh Run the onboarding script sudo /tmp/mde_onnboard.sh
How to Use It:
- Save this script to a file (e.g.,
mde_deploy.sh). - Use your existing orchestration tool (Ansible, Puppet, Chef) to push and execute this script on target Linux servers.
- Once onboarded, the dynamic device group rules will automatically tag the device and apply the appropriate security policies.
7. Exploiting Misconfigurations: A Defender Perspective
Understanding how an attacker might exploit weak configurations highlights the importance of this feature. An adversary could disable key protections on an unmanaged endpoint.
PowerShell Exploit Command (Example):
Set-MpPreference -DisableRealtimeMonitoring $true -DisableIOAVProtection $true
Mitigation via MDE Management:
This is precisely why centralized management is critical. MDE Management can enforce a policy that prevents these local changes from persisting. The managed policy will continuously revert such malicious modifications, ensuring real-time protection is always on. The Advanced Hunting query below can hunt for such tampering attempts:
DeviceEvents | where ActionType == "SecurityValueModified" | where AdditionalFields contains "DisableRealtimeMonitoring"
What Undercode Say:
- Key Takeaway 1: The introduction of dynamic device groups transforms MDE from a passive monitoring tool into an active, scalable governance platform for heterogeneous environments, finally closing the loop on unmanaged device risk.
- Key Takeaway 2: This move signifies a strategic shift by Microsoft to consolidate endpoint security management purely within its Defender XDR ecosystem, reducing reliance on Intune for core security policy enforcement and appealing to enterprises with complex, multi-platform infrastructures.
This analysis suggests that Microsoft is aggressively positioning Defender as a standalone security management suite. By solving the scalability problem of manual tagging, they have removed a significant barrier to adoption for large enterprises, particularly those with substantial Linux and Mac estates. This feature directly attacks a primary competitor differentiator and allows Microsoft to present a more unified and automated security story. The ability to manage policies dynamically based on device properties is a fundamental building block for autonomous security operations.
Prediction:
The automation of security policy assignment via dynamic groups will become the standard across the XDR market within 18 months. This hack—by which we mean this clever workaround now made official—demonstrates a future where security configurations are intrinsically adaptive. We predict this will evolve into behavior-driven policy management, where security settings on an endpoint will automatically tighten in real-time based on threat exposure levels, user behavior analytics, and active attack intelligence, moving from static compliance to dynamic, risk-based hardening.
🎯Let’s Practice For Free:
IT/Security Reporter URL:
Reported By: Jeffrey Appel – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
