In today’s complex threat landscape, perimeter defences are no longer enough. Insider threats—whether from malicious intent or compromised credentials—pose a significant risk to enterprise security. Microsoft Defender for Identity (MDI) is designed to detect these threats from within, providing deep insight into user behavior and directory activity across hybrid environments.

What is Microsoft Defender for Identity?

Formerly known as Azure Advanced Threat Protection (ATP), Defender for Identity is a cloud-based security solution that taps into your on-premises Active Directory (AD). It uses signals like authentication patterns, group membership changes, abnormal access attempts, and lateral movement behaviours to spot suspicious activity. Integration with Microsoft 365 Defender provides a broader security context and faster incident response.

How It Helps Detect Insider Threats

Defender for Identity employs user and entity behaviour analytics (UEBA) to baseline “normal” activity for each user. It then uses this intelligence to raise alerts when deviations occur. Key scenarios it detects include:

  • Credential theft and misuse: Pass-the-Ticket, Pass-the-Hash, and brute-force attacks.
  • Privilege escalations: Unexpected additions to Domain Admins or lateral movement attempts.
  • Reconnaissance and enumeration: These attempts to gather domain structure and user lists.
  • Suspicious VPN or remote logons that deviate from usual patterns.

This continuous monitoring provides early-warning detection, allowing security teams to investigate and contain incidents before significant damage is done.

Why It Matters

Organizations must be proactive, as hybrid infrastructures are becoming the norm and identity is the new perimeter. Insider threats, particularly those leveraging legitimate access, often bypass traditional defences.

Defender for Identity closes that gap by offering real-time visibility into how credentials and domain permissions are being used—whether by legitimate users or adversaries.

Quick Integration Tips

  • Sensor Deployment: Lightweight sensors install directly on your domain controllers or read-only domain controllers (RODCS).
  • Azure Integration: Seamlessly integrates with Microsoft 365 Defender and Sentinel for holistic incident correlation.
  • Baseline First: Allow behavioural baselining to mature, improving alert fidelity.
  • Review the Timeline View: Investigate alerts using the graphical attack timeline to trace movements across the environment.

Bottom line: Microsoft Defender for Identity offers more than threat detection—it provides foresight. When every second counts, the ability to identify subtle deviations in user behaviour could mean the difference between prevention and recovery.

Thanks,

Steve Labeau – Principal Consultant / Blogger