Entra ID Excessive Permission Changes to Application

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 rule entra_id_excessive_permission_change_to_app {

  meta:
    author = "Google Cloud Security"
    description = "Adding permissions to an application is expected, however if excessive permissions are changed at one time over a defined threshold, it may be worth validating."
    rule_id = "mr_7e13e4fc-6a6d-45c6-af92-69f98b4c9805"
    rule_name = "Entra ID Excessive Permission Changes to Application"
    reference = "https://learn.microsoft.com/en-us/graph/permissions-reference"
    type = "alert"
    platform = "azure"
    data_source = "azure ad"
    severity = "Medium"
    priority = "Medium"

  events:
    $app.metadata.event_type = "SERVICE_MODIFICATION"
    $app.metadata.product_event_type = "Update application"
    $app.metadata.product_name = "Azure AD Directory Audit"
    $app.metadata.vendor_name = "Microsoft"
    $app.security_result.action = "ALLOW"
    (
        (
            //used to tune application updates that are not permission related or where permissions before and after are the same
            $app.target.resource.attribute.labels["RequiredResourceAccess"] != "" and
            $app.src.resource.attribute.labels["RequiredResourceAccess"] != ""
        ) or
        $app.src.resource.attribute.labels["RequiredResourceAccess"] != $app.target.resource.attribute.labels["RequiredResourceAccess"]
    )
    $app.principal.user.userid = $userid

  match:
    $userid over 5m

  outcome:
    $risk_score = 65
    $event_count = count_distinct($app.metadata.id)
    $previous_permissions = array_distinct($app.src.resource.attribute.labels["RequiredResourceAccess"])
    $previous_permissions_count = max(strings.count_substrings($app.src.resource.attribute.labels["RequiredResourceAccess"], "EntitlementId:"))
    $current_permissions = array_distinct($app.target.resource.attribute.labels["RequiredResourceAccess"])
    $current_permissions_count = max(strings.count_substrings($app.target.resource.attribute.labels["RequiredResourceAccess"], "EntitlementId:"))
    $permission_delta = math.abs($current_permissions_count - $previous_permissions_count)
    $principal_county_region = array_distinct($app.principal.ip_geo_artifact.location.country_or_region)
    $principal_ip = array_distinct($app.principal.ip)
    $target_application = array_distinct($app.target.resource.name)

  condition:
    //adjust the permission delta to your desired threshold
    $app and $permission_delta > 5
}