Note
The experience described in this page can also be accessed at https://security.microsoft.com as part of Microsoft 365 Defender. The supporting documents for the new experience can be found here. For more information about Microsoft Defender for Identity and when other features will be available in Microsoft 365 Defender, see Microsoft Defender for Identity in Microsoft 365 Defender.
The Microsoft Defender for Identity Health Center lets you know when there’s a problem with your Defender for Identity instance, by raising a health alert. This article describes all the health alerts for each component, listing the cause and the steps needed to resolve the problem.
All domain controllers are unreachable by a sensor
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| The Defender for Identity sensor is currently offline due to connectivity issues to all the configured domain controllers. | This impacts Defender for Identity’s ability to detect suspicious activities related to domain controllers monitored by this Defender for Identity sensor. | Make sure the domain controllers are up and running and that this Defender for Identity sensor can open LDAP connections to them. In addition, in Settings make sure to configure a directory service account for every deployed forest. | Medium |
All/Some of the capture network adapters on a sensor are not available
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| All/Some of the selected capture network adapters on the Defender for Identity sensor are disabled or disconnected. | Network traffic for some/all of the domain controllers is no longer captured by the Defender for Identity sensor. This impacts the ability to detect suspicious activities, related to those domain controllers. | Make sure these selected capture network adapters on the Defender for Identity sensor are enabled and connected. | Medium |
Directory services user credentials are incorrect
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| The credentials for the directory services user account are incorrect. | This impacts sensors’ ability to detect activities using LDAP queries against domain controllers. | – For a standard AD accounts: Verify that the username, password, and domain in the Directory services configuration page are correct. – For group Managed Service Accounts: Verify that the username and domain in the Directory Services configuration page are correct. Also check all the other gMSA account prerequisites described on the Connect to your Active Directory Forest page. |
Medium |
Low success rate of active name resolution
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| The listed Defender for Identity sensors are failing to resolve IP addresses to device names more than 90% of the time using the following methods: – NTLM over RPC – NetBIOS – Reverse DNS |
This impacts Defender for Identity’s detections capabilities and might increase the number of false positive alarms. | – For NTLM over RPC: Check that port 135 is open for inbound communication from Defender for Identity sensors on all computers in the environment. – For reverse DNS: Check that the sensors can reach the DNS server and that Reverse Lookup Zones are enabled. – For NetBIOS: Check that port 137 is open for inbound communication from Defender for Identity sensors on all computers in the environment. Additionally, make sure that the network configuration (such as firewalls) isn’t preventing communication to the relevant ports. |
Low |
No traffic received from domain controller
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| No traffic was received from the domain controller via this Defender for Identity sensor. | This might indicate that port mirroring from the domain controllers to the Defender for Identity sensor isn’t configured yet or not working. | Verify that port mirroring is configured properly on your network devices.
On the Defender for Identity sensor capture NIC, disable these features in Advanced Settings: Receive Segment Coalescing (IPv4) Receive Segment Coalescing (IPv6) |
Medium |
Read-only user password to expire shortly
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| The read-only user password, used to perform resolution of entities against Active Directory, is about to expire in less than 30 days. | If the password for this user expires, all the Defender for Identity sensors stop running and no new data is collected. | Change the domain connectivity password and then update the password in the Defender for Identity portal. | Medium |
Read-only user password expired
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| The read-only user password, used to get directory data, expired. | All the Defender for Identity sensors stop running (or will stop running soon) and no new data is collected. | Change the domain connectivity password and then update the password in the Defender for Identity portal. | High |
Sensor outdated
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| A Defender for Identity sensor is outdated. | A Defender for Identity sensor is running a version that can’t communicate with the Defender for Identity cloud infrastructure. | Manually update the sensor and check to see why the sensor isn’t automatically updating. If this doesn’t work, download the latest sensor installation package and uninstall and reinstall the sensor. For more information, see Installing the Defender for Identity sensor. | Medium |
Sensor reached a memory resource limit
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| The Defender for Identity sensor stopped itself and restarts automatically to protect the domain controller from a low memory condition. | The Defender for Identity sensor enforces memory limitations upon itself to prevent the domain controller from experiencing resource limitations. This happens when memory usage on the domain controller is high. Data from this domain controller is only partly monitored. | Increase the amount of memory (RAM) on the domain controller or add more domain controllers in this site to better distribute the load of this domain controller. | Medium |
Sensor service failed to start
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| The Defender for Identity sensor service failed to start for at least 30 minutes. | This can impact the ability to detect suspicious activities originating from domain controllers being monitored by this Defender for Identity sensor. | Monitor Defender for Identity sensor logs to understand the root cause for Defender for Identity sensor service failure. | High |
Sensor stopped communicating
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| There has been no communication from the Defender for Identity sensor. The default time span for this alert is 5 minutes. | Network traffic is no longer captured by the network adapter on the Defender for Identity sensor. This impacts ATA’s ability to detect suspicious activities, since network traffic won’t be able to reach the Defender for Identity cloud service. | Check that the port used for the communication between the Defender for Identity sensor and Defender for Identity cloud service is not blocked by any routers or firewalls. | Medium |
Some domain controllers are unreachable by a sensor
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| A Defender for Identity sensor has limited functionality due to connectivity issues to some of the configured domain controllers. | Pass the Hash detection might be less accurate when some domain controllers can’t be queried by the Defender for Identity sensor. | Make sure the domain controllers are up and running and that this Defender for Identity sensor can open LDAP connections to them. | Medium |
Some Windows events are not being analyzed
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| The Defender for Identity sensor is receiving more events than it can process. | Some Windows events aren’t being analyzed, which can impact the ability to detect suspicious activities originating from domain controllers being monitored by this Defender for Identity sensor. | Verify that only required events are forwarded to the Defender for Identity sensor or try to forward some of the events to another Defender for Identity sensor. | Medium |
Some network traffic could not be analyzed
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| The Defender for Identity sensor is receiving more network traffic than it can process. | Some network traffic couldn’t be analyzed, which can impact the ability to detect suspicious activities originating from domain controllers being monitored by this Defender for Identity sensor. | Consider adding additional processors and memory as required. If this is a standalone Defender for Identity sensor, reduce the number of domain controllers being monitored.
This can also happen if you’re using domain controllers on VMware virtual machines. To avoid these alerts, you can check that the following settings are set to 0 or Disabled in the virtual machine: – TsoEnable – LargeSendOffload(IPv4) – IPv4 TSO Offload Also, consider disabling IPv4 Giant TSO Offload. For more information, see your VMware documentation. |
Medium |
Some ETW events are not being analyzed
| Alert | Description | Resolution | Severity |
|---|---|---|---|
| The Defender for Identity sensor is receiving more Event Tracing for Windows (ETW) events than it can process. | Some Event Tracing for Windows (ETW) events aren’t being analyzed, which can impact the ability to detect suspicious activities originating from domain controllers being monitored by this Defender for Identity sensor. | Make sure the sensor machine is sized correctly according to the sizing tool. If it is, contact support. | Medium |
Source : Official Microsoft Brand
Editor by : BEST Antivirus KBS Team
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