Power Apps - Multiple users access a malicious link after launching new app

Requête originale, sans modification.

// Define a threshold (distinct_user_launch_threshold) for
// the minimum number of users who launched an app
// to be in scope of this detection
let distinct_user_launch_threshold = 2;
// Define a threshold for the minumum number of users
// who clicked the same malicious link after launching the app
// to be in scope of this detection
let distinct_user_url_click_threshold = 2;
let query_frequency = 1h;
let query_lookback = 14d;
let new_app_creation_activity = materialize(
    PowerPlatformAdminActivity
    | where TimeGenerated >= ago (query_lookback)
    | where EventOriginalType == "CreatePowerApp"
    | extend Properties = tostring(PropertyCollection)
    | extend SrcIpAddr = extract(@'"enduser.ip_address","Value":"([^"]+)"', 1, Properties)
    | extend SrcIpAddr = iif(SrcIpAddr startswith '::ffff:', replace_string(SrcIpAddr, '::ffff:', ''), SrcIpAddr)
    | extend AppId = extract(@'"powerplatform.analytics.resource.power_app.id","Value":"([^"]+)"', 1, Properties)
    | extend AppId = tolower(replace_string(AppId, '/providers/Microsoft.PowerApps/apps/', ''))
    | extend
        AppName = extract(@'"powerplatform.analytics.resource.power_app.display_name","Value":"([^"]+)"', 1, Properties),
        EnvironmentId = extract(@'"powerplatform.analytics.resource.environment.id","Value":"([^"]+)"', 1, Properties)
    | project-rename
        AppCreatedTime = TimeGenerated,
        AppCreator = ActorName,
        AppCreatorIpAddr = SrcIpAddr
    );
let distinct_apps = new_app_creation_activity
    | distinct AppName;
let new_app_launch_activity = materialize(
    new_app_creation_activity
    | join kind=inner (
        PowerPlatformAdminActivity
        | where TimeGenerated >= ago (query_lookback)
        | where EventOriginalType == "LaunchPowerApp"
        | where PropertyCollection has_any (distinct_apps)
        | extend Properties = tostring(PropertyCollection)
        | extend AppName = extract(@'"powerplatform.analytics.resource.power_app.display_name","Value":"([^"]+)"', 1, Properties)
        | summarize FirstAppLaunchTime = min(TimeGenerated) by ActorName, AppName)
        on AppName
    | where FirstAppLaunchTime > AppCreatedTime
    );
let new_app_launch_users = new_app_launch_activity
    | summarize LaunchCount = dcount(ActorName) by AppName
    | where LaunchCount > distinct_user_launch_threshold
    | join kind=inner new_app_launch_activity on AppName
    | summarize
        by
        ActorName,
        FirstAppLaunchTime,
        AppName,
        AppId,
        EnvironmentId,
        AppCreator,
        AppCreatorIpAddr;
let detected_urls = union isfuzzy=true
        (
        SecurityAlert
        | where TimeGenerated >= ago (query_lookback)
        | where Entities has_cs '"Type":"url"'
        | mv-expand todynamic(Entities)
        | where tostring(Entities.Type) == "url"
        | project Url = tostring(Entities.Url), Source = "SecurityAlert"
        ),
        (
        ThreatIntelligenceIndicator
        | where TimeGenerated >= ago(query_lookback)
        | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
        | where Active == true and ExpirationDateTime > now()
        | where isnotempty(isnotempty(Url))
        | project Url, Source = "ThreatIntelligence"
        )
    | summarize by Url, Source;
let url_click_events = materialize(
    union isfuzzy=true
        (
        UrlClickEvents
        | where TimeGenerated >= ago(query_frequency)
        | where isnotempty(ThreatTypes)
        | join kind=inner (new_app_launch_users) on $left.AccountUpn == $right.ActorName
        | where TimeGenerated between (FirstAppLaunchTime .. (FirstAppLaunchTime + 1h))
        | summarize by ActorName, Url, Source = "MicrosoftDefender"
        ),
        (
        _Im_WebSession
        | where TimeGenerated >= ago(query_frequency)
        | join kind=inner (new_app_launch_users) on $left.SrcUsername == $right.ActorName
        | join kind=inner (detected_urls) on Url
        | where TimeGenerated between (FirstAppLaunchTime .. (FirstAppLaunchTime + 1h))
        | summarize by ActorName, Url, Source
        )
    );
let distinct_url_click_events_count = toscalar(
    url_click_events
    | summarize DistinctUserCount = dcount(ActorName) by Url
    | where DistinctUserCount > distinct_user_url_click_threshold
    | summarize sum(DistinctUserCount)
    );
url_click_events
| summarize DistinctUserCount = dcount(ActorName) by Url
| where DistinctUserCount >= distinct_user_url_click_threshold
| join kind=inner url_click_events on Url
| join kind=inner (new_app_launch_users) on ActorName
| extend
    PowerAppsEntityId = 27593,
    DataverseId = 32780,
    AccountName = tostring(split(ActorName, '@')[0]),
    UPNSuffix = tostring(split(ActorName, '@')[1])
| project
    FirstAppLaunchTime,
    AppCreator,
    AppName,
    AppId,
    ImpactedUser = ActorName,
    AccountName,
    UPNSuffix,
    EnvironmentId,
    Url,
    Source,
    PowerAppsEntityId