Microsoft 365 Defender: Detect and Respond with the “Continuous (NRT)”

Microsoft 365 Defender: Detect and Respond with the “Continuous (NRT)”

Today we are excited to announce the public preview of near real-time custom detections in Microsoft 365 Defender. This new frequency will allow you to respond to threats faster with automated responses and gain valuable time in stopping attacks and protecting your organization.

Automation is key to keeping up with attackers

While Microsoft’s eXtended Detection and Response (XDR) solution helps prioritize response activities and provides a unified experience that allows for more effective investigation at the incident level, the increasing volume and speed of sophisticated attacks remains challenging.

That’s why automation is becoming an increasingly important tool in optimizing the SOC process. Automating response actions for common alerts can help you stay on top of threats, protect your organization more effectively, and reduce response times. If you want to get started in Microsoft 365 Defender, check out this post.

For effective protection, most organizations have custom detection mechanisms in place that are unique to the requirements of their environment, but in order for these automations to be as effective as possible, the speed of detection is critical.

Detect in near real-time, respond in near real-time

To address the need for faster detections and response, we are thrilled to announce that you can now create custom detection rules that run in near real-time, in addition to existing frequencies ranging from every 24 hours to every hour. These detections can be integrated with the broad set of Microsoft 365 Defender across email, endpoint, and identity, leading to faster response times and faster mitigation of threats.

This means your custom logic will run and evaluate all available signals and alerts faster than ever before and will trigger your predefined response action immediately, once a match is detected.

This new frequency will be available in Microsoft 365 Defender as Continuous (NRT). Image 1 shows the configuration wizard for custom detection rules in Microsoft 365 Defender and the various frequency options you can choose from, including near real-time (NRT).


thumbnail image 1 captioned Image 1: Custom detection wizard with the frequency dropdown opened, new frequency of Continuous (NRT) is available.Image 1: Custom detection wizard with the frequency dropdown opened, new frequency of Continuous (NRT) is available.


When you configure a rule using the Continuous (NRT) frequency, the query is compared to every single event that gets into the service, and if there is a match, an alert is triggered. You can use the continuous frequency for queries referencing one table and using operators from the list of supported KQL operators.


Top use cases for custom detections and automated response actions


Monitoring for recent vulnerabilities

A common use case for a near real-time custom detection rule that we see with customers is monitoring for events that might indicate threat activity related to a recently disclosed vulnerability. For instance, you can use the DeviceProcessEvents table to look for the malicious string needed to exploit the Log4j vulnerability and configure remediation actions to run automatically on targeted devices, like initiating investigation on the device:


| where ProcessCommandLine matches regex @'(?i)\$\{jndi:(ldap|http|https|ldaps|dns|rmi|iiop):\/\/(\$\{([a-z]){1,20}:([a-z]){1,20}\})?(([a-zA-Z0-9]|-){2,100})?(\.([a-zA-Z0-9]|-){2,100})?\.([a-zA-Z0-9]|-){2,100}\.([a-z0-9]){2,20}(\/).*}'     
or InitiatingProcessCommandLine matches regex @'(?i)\$\{jndi:(ldap|http|https|ldaps|dns|rmi|iiop):\/\/(\$\{([a-z]){1,20}:([a-z]){1,20}\})?(([a-zA-Z0-9]|-){2,100})?(\.([a-zA-Z0-9]|-){2,100})?\.([a-zA-Z0-9]|-){2,100}\.([a-z0-9]){2,20}(\/).*}'


Detect and remove unwanted emails

Another use case is to look for unwanted emails, that may not necessarily be malicious but have been defined by the organization as unwanted and need to be automatically removed as soon as they are delivered. This empowers security admins to more easily manage mail flows from a security lens and can be done by configuring a Soft Delete remediation action:


| where Subject contains "This account has been suspended!"
| where SenderFromAddress == "[email protected]"
| where UrlCount > 0


An example of another scenario is to look for messages that spoof the recipient from a particular IP subnet and blocking this activity.


| where SenderIPv4 startswith "xx.xx.xx." and SenderFromAddress == RecipientEmailAddress


Automation is critical to creating efficiencies in your SOC, but the speed of detection is fundamental to an effective response and keeping your organization safe.

The ability to define custom rules for near real-time detections is in public preview starting today and will enable your defenders to create effective response mechanisms with the breadth of Microsoft 365 Defender’s XDR signal across endpoints, email and more.


Learn more

  • Check out our documentation and explore how near real-time custom detections can enhance your SOC’s detection and response processes
  • Wondering which tables are supported by near real-time detections? Find them here.
  • Start automating your response actions today.
  • Near real-time detections are available in public preview starting today. We would love to know what you think. Share your feedback with us in the Microsoft 365 Defender portal or by emailing [email protected].


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