power users, executives with heavy ai workloads, employees traveling for business, users accessing multiple copilot applications legitimately, or teams using shared corporate accounts across different office locations may trigger false positives.

Techniques

T1078

Sample rules

M365 Copilot Application Usage Pattern Anomalies

source: splunk
technicques:
- T1078

Description

Detects M365 Copilot users exhibiting suspicious application usage patterns including multi-location access, abnormally high activity volumes, or access to multiple Copilot applications that may indicate account compromise or automated abuse. The detection aggregates M365 Copilot Graph API events per user, calculating metrics like distinct cities/countries accessed, unique IP addresses, number of different Copilot apps used, and average events per day over the observation period. Users are flagged when they access Copilot from multiple cities (cities_count > 1), generate excessive daily activity (events_per_day > 100), or use more than two different Copilot applications (app_count > 2), which are anomalous patterns suggesting credential compromise or bot-driven abuse.

Detection logic

`m365_copilot_graph_api` (appDisplayName="*Copilot*" OR appDisplayName="M365ChatClient" OR appDisplayName="OfficeAIAppChatCopilot") 
| eval user = userPrincipalName 
| stats count as events,
    dc(location.city) as cities_count,
    values(location.city) as city_list,
    dc(location.countryOrRegion) as countries_count,
    values(location.countryOrRegion) as country_list,
    dc(ipAddress) as ip_count,
    values(ipAddress) as ip_addresses,
    dc(appDisplayName) as app_count,
    values(appDisplayName) as apps_used,
    dc(resourceDisplayName) as resource_count,
    values(resourceDisplayName) as resources_accessed,
    min(_time) as first_seen,
    max(_time) as last_seen
    by user

| eval days_active = round((last_seen - first_seen)/86400, 1) 
| eval first_seen = strftime(first_seen, "%Y-%m-%d %H:%M:%S") 
| eval last_seen = strftime(last_seen, "%Y-%m-%d %H:%M:%S") 
| eval events_per_day = if(days_active > 0, round(events/days_active, 2), events) 
| where cities_count > 1 OR events_per_day > 100 OR app_count > 2 
| sort -events_per_day, -countries_count 
| `m365_copilot_application_usage_pattern_anomalies_filter`