Identity attacks often use legitimate protocols, valid credentials, and ordinary administrative tools. That makes them difficult to distinguish from normal operations without context about accounts, domain controllers, authentication, privilege, and lateral movement. Microsoft Defender for Identity provides identity-focused detections and investigation context in the Microsoft Defender portal, helping the SOC see when Active Directory and related identity activity forms part of a broader attack.
For the current SC-200 role, identity investigation sits beside endpoint, Sentinel, Purview, and Defender for Cloud operations. The identity-administration depth represented by SC-300 is equally important because analysts need to understand how roles, authentication, service accounts, and hybrid identity are supposed to work before they can recognize abuse.
Treat hybrid identity as one attack surface
Many enterprises use on-premises Active Directory together with Microsoft Entra ID, synchronization components, federated services, and cloud applications. Attackers can move in either direction. Compromising an on-premises account can create a path toward cloud privilege, while a cloud identity can expose services that reach back into the datacenter.
Map the trust relationships between domain controllers, Entra Connect or other synchronization infrastructure, privileged groups, service accounts, certificate services, and cloud roles. Defenders for individual products can generate useful alerts, but responders need an architecture view that explains which identity systems can influence each other.
The current SC-100 architecture perspective is helpful because the question is not only “Which alert fired?” It is “What privilege can this identity reach next, and which control plane would be affected if the account is truly compromised?”
Document the identity systems that are authoritative for each account type. Hybrid organizations may have cloud-only users, synchronized users, service accounts, local administrators, and workload identities. Investigation is faster when analysts know where credentials are managed and which system can revoke access effectively.
Protect the telemetry path from domain controllers and identity systems
Defender for Identity relies on sensors and identity telemetry to recognize suspicious behavior. Sensor health therefore becomes part of detection coverage. If a domain controller is not monitored or a sensor is degraded, the absence of an alert is weaker evidence than it appears.
Monitor sensor status, deployment coverage, and the identity roles present on monitored servers. Microsoft has continued expanding sensor capabilities, including support across more identity roles. Keep deployment guidance current and verify that newly promoted domain controllers or infrastructure changes do not create blind spots.
Traditional Active Directory administration knowledge remains useful during investigation. The commands and objects covered in Active Directory PowerShell illustrate the kind of directory state responders may need to inspect when an alert involves group membership, accounts, or domain configuration.
Sensor deployment should be part of change management for domain infrastructure. New domain controllers, role migrations, or network changes can alter visibility. Security teams should receive notification when identity infrastructure changes so monitoring coverage is validated before the change is considered complete.
Security teams should also monitor who can uninstall, reconfigure, or otherwise interfere with sensors and identity-monitoring infrastructure. Attackers with administrative access may try to reduce visibility before using stolen credentials. Changes to monitoring components deserve alerting and audit just like changes to authentication policy.
Recognize credential-access behavior before it becomes lateral movement
Credential attacks include password guessing, ticket theft, pass-the-hash, pass-the-ticket, Kerberos abuse, and theft of session or authentication material. Some techniques generate obvious failures, while others use valid credentials and may look normal unless the sequence or source is unusual.
Investigate the account, device, authentication protocol, time, and surrounding directory activity together. A single successful logon may be benign; the same logon after a suspicious ticket request and followed by remote access to a sensitive host changes the story. Identity detections should be interpreted as part of an attack chain.
Strong authentication in the cloud reduces some credential risks but does not eliminate social engineering. Guidance on MFA fatigue attacks remains relevant because an attacker who obtains a password may try to turn repeated prompts into a valid cloud session.
Credential-theft investigations should include recent password resets, MFA registrations, token revocations, and authentication-method changes. Attackers often try to preserve access after initial compromise. A clean sign-in history after a reset does not prove recovery if a new credential or application consent remains.
Investigate lateral movement as a relationship problem
Lateral movement occurs when an attacker uses one compromised identity or device to reach another system. Defender for Identity alerts can identify behaviors associated with ticket replay, suspicious remote authentication, and other identity movement. The key question is not just whether a protocol was used, but whether the account and source are expected to use it.
Build context around privileged paths. Which users can sign in to domain controllers? Which service accounts have local administrator rights on many servers? Which machines can administer certificate services or synchronization infrastructure? Weak administrative topology can turn one compromised endpoint into broad domain access.
Use endpoint and identity evidence together. Defender XDR can correlate signals across products so a suspicious process on a workstation, an identity alert, and later activity on another device can appear in one incident. That correlation helps analysts avoid investigating each alert as if it were independent.
Review administrative paths that bypass normal user logon. Remote service management, scheduled tasks, PowerShell remoting, and management tools can all be legitimate ways to move between systems. Baseline which identities use them and from which management hosts so unusual use becomes easier to recognize.
Use identity security posture to reduce opportunities for abuse
Identity threat detection is stronger when the environment has fewer dangerous relationships. Remove stale privileged group memberships, reduce service-account permissions, protect legacy protocols, and review risky configurations. Findings that identify exposed paths should become hardening work, not just investigation context.
Privilege governance also matters. Eligible or time-bound administrative access through PIM can reduce standing privilege, while access reviews can remove assignments that no longer have a business purpose. When an incident occurs, responders should know whether the account was expected to be privileged at that moment.
The broader identity and access administration model connects lifecycle, authentication, authorization, and governance. Security operations benefits when those controls produce clear, trustworthy state instead of a directory full of historical exceptions.
Identity posture work should prioritize control-plane relationships that attackers can chain. A nonprivileged account that can modify a group, a group that owns an application, and an application with directory permissions can form a privilege path even when no single assignment looks dangerous in isolation.
Prioritize privileged identities and identity infrastructure
Not every account compromise has equal impact. Domain admins, Entra administrators, synchronization accounts, certificate-service operators, service accounts with broad reach, and automation identities deserve tighter monitoring and faster response. Tag or otherwise classify high-value identities so incidents involving them receive appropriate severity.
Identity infrastructure itself is critical. A domain controller, federation server, or synchronization system can become a stepping stone to many accounts. Harden these systems, minimize interactive sign-in, restrict administration, and monitor configuration changes. Treat their compromise as a control-plane incident rather than an ordinary endpoint alert.
Break-glass and emergency accounts require special handling. They may intentionally bypass some routine controls, which makes monitoring more important, not less. Any unexpected use should trigger investigation and review of downstream changes.
For high-value identities, reduce routine productivity use. Administrators who browse email and the web with the same account used for control-plane changes expose privilege to more phishing and token-theft opportunities. Separate privileged identities and administrative workstations where the risk justifies it.
Create separate escalation paths for identity control-plane incidents. Compromise of a domain controller, synchronization server, certificate authority, or high-privilege directory role can invalidate assumptions about many downstream accounts. Response may need enterprise-wide credential resets or trust restoration rather than ordinary endpoint cleanup.
Correlate identity alerts with endpoint, cloud, and email evidence
Attackers frequently enter through phishing or endpoint compromise before abusing identity. Review recent email, browser, process, and device activity around the affected user. A suspicious sign-in is more meaningful when the same device also launched credential-dumping tools or received a malicious attachment.
Cloud resource activity can also confirm impact. After a role change or suspicious token use, check whether the identity accessed Key Vault, modified network rules, created service principals, or altered storage. The incident should trace what the identity actually did after authentication.
This is where a unified XDR model is more useful than product-by-product alert queues. Correlation provides a chronology and entity graph that can show whether an identity alert is the beginning, middle, or consequence of a larger attack.
Cross-product correlation is only as reliable as the entity identifiers. Ensure synchronized accounts and devices can be matched consistently across Entra, Defender for Identity, Defender for Endpoint, and Sentinel. Ambiguous names can fragment one attack into several unrelated-looking records.
Use the identity timeline to test competing explanations
Good investigation asks what else could explain the alert. Was the user traveling? Did an administrator perform planned maintenance? Was a service account moved to a new host? Review historical activity, sign-in patterns, group changes, device context, and related alerts before deciding.
Build a timeline that separates observed evidence from assumptions. Record when the suspicious authentication occurred, what privilege existed, what resources were accessed, and what response actions followed. This helps avoid confirmation bias and makes handoff between analysts clearer.
If the evidence remains uncertain, preserve the incident and increase monitoring rather than forcing a binary conclusion. Security operations often works with incomplete information. The goal is to reduce uncertainty quickly enough to protect the environment.
When building the timeline, note which events are detections and which are raw observations. An alert is an interpretation; a successful Kerberos request, group change, or process execution is an event. Separating those layers makes it easier to challenge assumptions and explain conclusions during review.
Contain identity compromise without losing the investigation
Response may include revoking sessions, disabling accounts, removing role assignments, resetting credentials, isolating devices, or blocking malicious infrastructure. Choose actions according to confidence and business impact. A service account may require coordinated credential rotation to avoid an outage, while a compromised user account can often be disabled immediately.
Before destructive cleanup, preserve enough evidence to understand persistence and downstream actions. Review new credentials, group memberships, application registrations, scheduled tasks, certificates, and other changes the attacker may have created. Restoring the password alone does not remove access that was established through another mechanism.
After containment, feed lessons back into identity architecture and detections. If the incident depended on standing privilege, weak MFA, or a broad service account, fix the condition. The best identity investigation ends with a smaller attack surface than the one that existed before the alert.
Recovery should include validation that old credentials and sessions no longer work. Test critical accounts after revocation, review privileged group membership, and watch for repeated authentication from the original source. Containment is not complete until the attacker’s known access paths are demonstrably closed.