ms_graph_search_query

rule ms_graph_search_query {

  meta:
    author = "Google Cloud Security"
    description = "This detects when the search/query endpoint is called which can be used for enumeration of items like SharePoint site URLs. GraphRunner contains a function called Get-SharePointSiteURLs but other tools may as well."
    rule_id = "mr_19ac0f85-970c-4eca-9832-72aaed1ee311"
    rule_name = "Hunt for search/query endpoint API requests in the Microsoft Graph"
    reference = "https://github.com/dafthack/GraphRunner/blob/main/GraphRunner.ps1"
    assumption = "Applications that perform this action will need to be filtered and thresholding in the condition could be added for additional tuning as needed"
    type = "hunt"
    data_source = "MS Graph Activity Logs"
    platform = "Azure"
    severity = "Low"
    priority = "Low"

  events:
    $api.metadata.event_type = "NETWORK_HTTP"
    $api.metadata.product_event_type = "Microsoft Graph Activity"
    $api.target.url = "https://graph.microsoft.com/v1.0/search/query" nocase
    //Can be tuned for specific User Agent strings being used - by default GraphRunner does not forge the UA for this action
    //$api.network.http.user_agent = /PowerShell/ nocase
    $api.network.http.method = "POST"
    $api.network.http.response_code = 200
    $api.principal.ip = $ip
    $api.network.session_id = $session

  match:
    $ip, $session over 5m

  outcome:
    $risk_score = 35
    $event_count = count_distinct($api.metadata.id)
    $requesting_user_guid = array_distinct($api.principal.user.userid)
    $requesting_ip = array_distinct($api.principal.ip)
    $user_agent = array_distinct($api.network.http.user_agent)
    $location = array_distinct($api.principal.location.name)
    $target_application_id_guid = array_distinct($api.target.resource.product_object_id)
    $session_id = array_distinct($api.network.session_id)
    $target_url = array_distinct($api.target.url)

  condition:
    $api
}