Resilience with Microsoft Defender XDR

Understanding Microsoft Defender XDR

Microsoft Defender XDR (Extended Detection and Response), formerly known as Microsoft 365 Defender, is an integrated threat protection suite designed to detect and mitigate malicious activity across various attack vectors.

It encompasses detection capabilities across key areas, including:

• Email
• Endpoints
• Applications
• Identity

1. Detection of threat

• The journey begins with the detection of a potential threat, such as a malicious email or a compromised endpoint.
• Microsoft Defender for Endpoints (MDE) plays a crucial role in identifying and alerting security operations teams about such incidents. MDE communicates to Intune that the risk level on this endpoint has changed.

2. Access restricted

• When MDE notifies Intune, an Intune compliance policy configured with an MDE risk level severity is triggered and marks the account as non-compliant with organization’s policies
• This in turn updates the compliance status of the device in Microsoft Entra ID. The Conditional Access created in Microsoft Entra ID blocks user’s access to all new requests and any current access to resources that support Continuous Access Evaluation (CAE).

3. Remediation

Remediation can be done with MDE via several ways:

• Automated remediation
• Approval of security analyst for automated remediation
• Manual investigation of threat

4. Restore access

• Once the infected devices are remediated, MDE signals Intune to change the device risk status by updating Microsoft Entra ID.
• Microsoft Entra ID Conditional Access allows access to enterprise resources.

5. Share intelligence

• Microsoft Defender XDR facilitates the sharing of threat intelligence across the organization, enabling proactive threat hunting and enhancing the overall security posture.
• Threat intelligence teams leverage this information to identify emerging threats, analyze attack trends, and provide strategic insights to inform security strategies and priorities.

Microsoft Defender XDR in a Security Operations Center (SOC)

The following diagram portrays how XDR and Sentinel are integrated in SOC:

SECURITY OPERATIONS MODEL

The SOC model encompasses tiered levels of expertise, with each tier responsible for specific tasks ranging from automated alert handling to advanced threat hunting and forensics.

Automation

• Near real-time resolution of known incident types with automation. These are well-defined attacks that the organization has seen many times.

Tier 1: Triage

• Triage analysts focus on rapid remediation of a high volume of well-known incident types that still require (quick) human judgment.
• These are often tasked with approving automated remediation workflows and identifying anything anomalous or interesting that warrant escalation or consultation with investigation (Tier 2) teams.
• 90% true positive —Setting a quality standard of 90% true positive is recommended for any alert feeds that require an analyst to respond, so that analysts aren’t required to respond to a high volume of false alarms.

Tier 2: Investigation and Incident Management

• This team serves as the escalation point for issues from Triage (Tier 1)
• Proactively, this team also periodically reviews the Triage team alert queue and can proactively hunt using XDR tools in their spare time.
• This team pilots new/unfamiliar alert types to document processes for Triage team and automation, often including alerts generated by Microsoft Defender for Cloud on cloud hosted apps, VMs, containers and Kubernetes, SQL databases, etc.

Tier 3: Hunt and Incident Management

• This team proactively hunts for undetected threats, assists with escalations and advanced forensics for reactive investigations, and refines alerts/automation.
• These teams operate in more of a hypothesis-driven model than a reactive alert model and are also where red/purple teams connect with security operations.

Conclusion

By providing comprehensive threat detection, rapid response capabilities, and seamless integration with existing security infrastructure, Defender XDR enables security teams to stay ahead of cyber adversaries and safeguard critical assets. As organizations continue to embrace digital transformation, investing in advanced threat protection solutions like Microsoft Defender XDR is paramount to ensure a secure and resilient IT environment.

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