Entra ID Admin Login Activity to Uncommon MS Cloud Apps

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rule entra_id_admin_login_activity_to_uncommon_mscloud_apps {

  meta:
    author = "Google Cloud Security"
    description = "Detects Azure AD admin login activity to apps other than a defined list of first party MS Cloud Apps. Note that Azure Active Directory PowerShell and custom Azure apps are not in this list by default"
    rule_id = "mr_59c94dc1-b7af-412c-aa2d-4b5834474f19"
    rule_name = "Entra ID Admin Login Activity to Uncommon MS Cloud Apps"
    assumption = "The lists first_party_ms_cloud_apps and entra_id_admin_watchlist are populated as needed"
    tactic = "TA0001"
    technique = "T1078.004"
    reference = "https://learn.microsoft.com/en-us/troubleshoot/azure/active-directory/verify-first-party-apps-sign-in"
    type = "alert"
    platform = "azure"
    data_source = "azure ad"
    severity = "Medium"
    priority = "Medium"

  events:

    $login.metadata.event_type = "USER_LOGIN"
    $login.metadata.product_name = "Azure AD"
    $login.metadata.vendor_name = "Microsoft"
    $login.security_result.action = "ALLOW"
    not $login.target.resource.attribute.labels["App Id"] in %first_party_ms_cloud_apps

    //Use the list below to isolate activity to admins
    //@domain.com is stripped off to reduce the values in the list to just the username of the email address
    re.replace($login.target.user.userid, `@.*$`, "") in %entra_id_admin_watchlist
    $login.target.user.userid = $userid

  match:
    $userid over 5m

  outcome:
    $risk_score = 65
    $event_count = count_distinct($login.metadata.id)
    $target_application = array_distinct($login.target.application)
    $security_description = array_distinct($login.security_result.description)
    $security_summary = array_distinct($login.security_result.summary)
    $country_region_login_attempt = array_distinct(strings.concat($login.principal.location.city," ",$login.principal.location.state," ",$login.principal.location.country_or_region))
    $user_agent = array_distinct($login.network.http.user_agent)
    $principal_ip = array_distinct($login.principal.ip)

  condition:
    $login
}