3.5 Investigating Insider Risk Alerts and Managing Cases

Investigating Insider Risk Alerts and Managing Cases

Introduction

Subsection 3.4 taught you how IRM policies detect insider threats through behavioral patterns and risk score escalation. This subsection teaches you what happens when an alert fires — the investigation workflow that takes you from an anonymized risk signal to a documented case with evidence, stakeholder coordination, and resolution.

IRM investigation differs from standard security incident response in three fundamental ways. First, the subject of the investigation is an employee, not an external attacker — which introduces employment law, privacy law, and HR policy considerations that do not apply to external threat investigations. Second, the investigation involves pseudonymized data that must be de-anonymized through a controlled process — you cannot simply look up the user’s name. Third, the outcome may be a personnel action (termination, disciplinary action, legal proceedings) rather than a technical remediation (password reset, device isolation) — which requires coordination with HR and legal counsel, not just the SOC team.

These differences do not make IRM investigations more difficult. They make them more procedurally sensitive. This subsection teaches you the procedures.

The IRM investigation workflow

Step 1: Triage — pseudonymized review. IRM alerts appear in the Purview portal’s Insider Risk Management → Alerts section. By default, the user identity is pseudonymized — you see “User-3847” instead of the employee’s name. Review the alert’s risk score, the indicators that contributed to it, the policy that triggered, and the behavioral timeline. At this stage, you are determining whether the alert warrants investigation, not who the user is.

Most IRM alerts at triage are Low or Medium severity and can be resolved without de-anonymization. A user who downloaded 20% more files than their daily average for one day and then returned to normal does not warrant identification. Document the triage outcome and close the alert as “Benign — within acceptable deviation.”

Step 2: De-anonymization — authorized identification. For alerts that warrant investigation (High or Critical severity, completed sequences, risk scores above the configured threshold), the next step is identifying the user. De-anonymization requires the Insider Risk Management Investigator role (not just the Analyst role). Clicking “Resolve anonymization” reveals the user’s name, department, manager, and employment details. This action is logged in the IRM audit trail — there is a permanent record that you de-anonymized this user at this time for this alert.

Step 3: Deep review — activity timeline and content explorer. After de-anonymization, you have access to the user’s full activity timeline within IRM. This timeline shows every monitored action chronologically: file downloads with file names and labels, email sends with recipients and attachment details, USB device connections with device identifiers, SharePoint sharing changes, browser activity to cloud storage sites, and printing activity.

The content explorer (available in cases, not just alerts) lets you view the actual content involved — the files that were downloaded, the emails that were sent, the documents that were printed. This is IRM’s forensic evidence layer: you can see not just that the user downloaded 500 files, but which 500 files they downloaded and whether any contained sensitive data.

Step 4: Create case — HR and legal coordination. When the deep review confirms that the user’s behavior warrants formal investigation, create an IRM case. The case is a formal investigation container that tracks the investigation, stores evidence, records analyst actions, and facilitates stakeholder coordination.

Before creating the case, notify HR and legal counsel. IRM investigations that may result in personnel actions (termination, disciplinary action) require HR involvement. Investigations that may result in legal proceedings (civil or criminal action for data theft) require legal counsel involvement. In many organizations, the SOC analyst does not create the IRM case directly — they present the alert findings to a cross-functional review team that includes HR, legal, and security, and the team collectively decides whether to open a formal case.

Step 5: Investigate — collect evidence. With the case created and stakeholders engaged, conduct the formal investigation. Review the complete activity timeline. Identify every data artifact involved (which files, which emails, which documents). Determine whether data left the organization (check DLP alerts, check email delivery status, check browser upload activity). If data did leave, determine where it went and whether it can be recovered or contained.

If the investigation requires locating specific content (the exact files the user downloaded, the exact emails they forwarded), escalate to eDiscovery (subsection 3.8) for content search. eDiscovery preserves the content as evidence and can place it on legal hold to prevent deletion.

If the investigation overlaps with a security incident (the user’s account may also be compromised, or the insider risk behavior may have been triggered by an external attacker who gained access to the account), coordinate with the SOC incident response workflow from Module 1.2. The IRM investigation and the security investigation run in parallel, sharing findings through the cross-functional review team.

Step 6: Resolve — determine outcome and close. The resolution depends on the investigation findings and the cross-functional team’s decision.

Benign — the behavior was legitimate. The user downloaded files for a valid business purpose, the pattern happened to match a risk profile, and no data theft occurred. Close the case with documentation of the finding. No personnel action.

Policy violation — the user’s behavior violated data handling policies but was not malicious. The user forwarded documents to their personal email for convenience, not for theft. Resolution: policy retraining, manager notification, potential written warning depending on HR policy.

Data theft confirmed — the user deliberately exfiltrated organizational data. Resolution depends on the organization’s response policy and legal counsel’s advice: immediate termination, legal action to recover the data, regulatory notification if personal data was involved, and potential criminal referral for severe cases.

Account compromise — the IRM alert was triggered by an attacker operating through a compromised account, not by the employee’s own actions. Transfer the case to the standard security incident response workflow. The employee is a victim, not a subject.

Evidence handling in IRM investigations

IRM evidence requires careful handling because it may be used in employment proceedings, civil litigation, or criminal prosecution. Standard security incident evidence handling (Module 14) applies, with additional requirements specific to employee investigations.

Chain of custody. Every evidence artifact (file download records, email metadata, activity timelines) must have a documented chain of custody showing when it was collected, by whom, from which system, and how it was stored. IRM’s built-in audit logging provides part of this chain, but you should also document your own investigation actions in the case notes.

Legal hold coordination. If legal counsel determines that the investigation may lead to litigation, request an eDiscovery legal hold on the user’s mailbox, OneDrive, and relevant SharePoint sites. This preserves all content from deletion — even if the user attempts to cover their tracks by deleting emails or files. Legal hold is a legal action, not a technical one — it requires authorization from legal counsel, not just the SOC analyst.

Interview coordination. If the investigation leads to an employee interview (typically conducted by HR, not by the SOC analyst), the IRM activity timeline provides the factual basis for the interview questions. Provide HR with a sanitized summary of the findings — specific actions, dates, and data volumes — without sharing the raw IRM interface. HR does not need access to the IRM system. They need the investigation findings presented in a format they can use in the interview.

IRM investigation vs standard security IR: the key differences

IRM investigations and standard security incident response follow similar investigative logic (detect, investigate, contain, remediate) but differ in critical procedural aspects that affect how you conduct the investigation.

Correlating IRM alerts with security events

Some IRM alerts overlap with security incidents. A compromised account may trigger both security alerts (anomalous sign-in from Defender) and insider risk alerts (anomalous data access from IRM). Determining whether the user is an insider threat or a victim of account compromise changes the entire investigation direction and response.

Use Sentinel to correlate IRM triggering signals with security event data. If an IRM alert fires for a user whose account also shows anomalous sign-in patterns from an unusual IP (check SigninLogs), the behavior may be attacker-driven rather than employee-driven. If the sign-in activity is normal (corporate IP, normal device, normal hours) but the data access pattern is anomalous, the behavior is more likely employee-driven.

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// Correlate IRM user activity with sign-in anomalies
let irmUser = "j.morrison@northgateeng.com";
let irmWindow = 7d;
SigninLogs
| where TimeGenerated > ago(irmWindow)
| where UserPrincipalName =~ irmUser
| where ResultType == "0"
| extend Country = tostring(LocationDetails.countryOrRegion)
| summarize SigninCount = count(),
    Countries = make_set(Country, 10),
    IPs = dcount(IPAddress),
    RiskySignins = countif(RiskLevelDuringSignIn in ("medium", "high"))
    by bin(TimeGenerated, 1d)
| order by TimeGenerated desc

If RiskySignins > 0 during the same period as the IRM alert, escalate to the security team for parallel investigation. If all sign-ins are from normal locations with zero risk, the behavior is coming from the legitimate user — proceed with the IRM workflow.

Adaptive Protection: automated DLP enforcement from IRM risk scores

Adaptive Protection is the integration point between IRM and DLP. When IRM calculates a user’s risk score as elevated, Adaptive Protection can automatically apply stricter DLP policies to that user — without manual intervention.

For example: a user with a normal risk score is subject to standard DLP policies (warn on external sharing, block only bulk sensitive data). When their IRM risk score escalates to High (they triggered multiple indicators after a resignation event), Adaptive Protection automatically applies a stricter DLP policy: block all external sharing, block USB copy, and alert on any file download above a threshold. This dynamic enforcement tightens data protection specifically for users who are exhibiting risky behavior, without affecting the rest of the organization.

For SOC analysts, Adaptive Protection means that DLP alert volume for high-risk users may increase during an IRM investigation — because the user is subject to stricter policies that generate more alerts. This is expected behavior, not a sudden increase in data exposure. Check the DLP policy name in the alert: if it references “Adaptive” or a risk-level-based policy, the alert was triggered by the IRM-driven policy escalation, not by a new data exposure event.

Knowledge check