Office 365 - Sharepoint File Transfer Above Threshold

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Id	abd6976d-8f71-4851-98c4-4d086201319c
Rulename	Office 365 - Sharepoint File Transfer Above Threshold
Description	Identifies Office365 Sharepoint File Transfers with a distinct folder count above a certain threshold in a 15-minute time period. Please note that entity mapping for arrays is not supported, so when there is a single value in an array, we will pull that value from the array as a single string to populate the entity to support entity mapping features within Sentinel. Additionally, if the array is multivalued, we will input a string to indicate this with a unique hash so that matching will not occur.
Severity	Medium
Tactics	Exfiltration
Techniques	T1020
Required data connectors	AzureActiveDirectory
Kind	Scheduled
Query frequency	15m
Query period	15m
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Global Secure Access/Analytic Rules/Office 365 - sharepoint_file_transfer_folders_above_threshold.yaml
Version	1.0.5
Arm template	abd6976d-8f71-4851-98c4-4d086201319c.json

KQL

let threshold = 500;
EnrichedMicrosoft365AuditLogs
| where Workload has_any("SharePoint", "OneDrive") and Operation has_any("FileDownloaded", "FileSyncDownloadedFull", "FileSyncUploadedFull", "FileUploaded")
| extend EventSource = tostring(parse_json(tostring(AdditionalProperties)).EventSource)
| extend UserAgent = tostring(parse_json(tostring(AdditionalProperties)).UserAgent)
| summarize count_distinct_ObjectId = dcount(ObjectId), dirlist = make_set(ObjectId, 10000) by UserId, ClientIp, UserAgent, bin(TimeGenerated, 15m)
| where count_distinct_ObjectId >= threshold
| extend DirSample = iff(array_length(dirlist) == 1, tostring(dirlist[0]), strcat("SeeDirListField","_", tostring(hash(tostring(dirlist)))))
| extend AccountName = tostring(split(UserId, "@")[0]), AccountUPNSuffix = tostring(split(UserId, "@")[1])

YAML

queryPeriod: 15m
version: 1.0.5
tactics:
- Exfiltration
queryFrequency: 15m
id: abd6976d-8f71-4851-98c4-4d086201319c
triggerOperator: gt
requiredDataConnectors:
- dataTypes:
  - EnrichedMicrosoft365AuditLogs
  connectorId: AzureActiveDirectory
severity: Medium
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Global Secure Access/Analytic Rules/Office 365 - sharepoint_file_transfer_folders_above_threshold.yaml
entityMappings:
- entityType: Account
  fieldMappings:
  - columnName: UserId
    identifier: FullName
  - columnName: AccountName
    identifier: Name
  - columnName: AccountUPNSuffix
    identifier: UPNSuffix
- entityType: IP
  fieldMappings:
  - columnName: ClientIp
    identifier: Address
- entityType: File
  fieldMappings:
  - columnName: DirSample
    identifier: Name
triggerThreshold: 0
relevantTechniques:
- T1020
query: |
  let threshold = 500;
  EnrichedMicrosoft365AuditLogs
  | where Workload has_any("SharePoint", "OneDrive") and Operation has_any("FileDownloaded", "FileSyncDownloadedFull", "FileSyncUploadedFull", "FileUploaded")
  | extend EventSource = tostring(parse_json(tostring(AdditionalProperties)).EventSource)
  | extend UserAgent = tostring(parse_json(tostring(AdditionalProperties)).UserAgent)
  | summarize count_distinct_ObjectId = dcount(ObjectId), dirlist = make_set(ObjectId, 10000) by UserId, ClientIp, UserAgent, bin(TimeGenerated, 15m)
  | where count_distinct_ObjectId >= threshold
  | extend DirSample = iff(array_length(dirlist) == 1, tostring(dirlist[0]), strcat("SeeDirListField","_", tostring(hash(tostring(dirlist)))))
  | extend AccountName = tostring(split(UserId, "@")[0]), AccountUPNSuffix = tostring(split(UserId, "@")[1])  
kind: Scheduled
name: Office 365 - Sharepoint File Transfer Above Threshold
customDetails:
  TransferCount: count_distinct_ObjectId
  FilesList: dirlist
description: |
  Identifies Office365 Sharepoint File Transfers with a distinct folder count above a certain threshold in a 15-minute time period.
  Please note that entity mapping for arrays is not supported, so when there is a single value in an array, we will pull that value from the array as a single string to populate the entity to support entity mapping features within Sentinel. Additionally, if the array is multivalued, we will input a string to indicate this with a unique hash so that matching will not occur.  
incidentConfiguration:
  createIncident: true
  groupingConfiguration:
    enabled: true
    reopenClosedIncident: false
    matchingMethod: Selected
    groupByCustomDetails: []
    groupByAlertDetails: []
    lookbackDuration: 5h
    groupByEntities:
    - Account

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/abd6976d-8f71-4851-98c4-4d086201319c')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/abd6976d-8f71-4851-98c4-4d086201319c')]",
      "properties": {
        "alertRuleTemplateName": "abd6976d-8f71-4851-98c4-4d086201319c",
        "customDetails": {
          "FilesList": "dirlist",
          "TransferCount": "count_distinct_ObjectId"
        },
        "description": "Identifies Office365 Sharepoint File Transfers with a distinct folder count above a certain threshold in a 15-minute time period.\nPlease note that entity mapping for arrays is not supported, so when there is a single value in an array, we will pull that value from the array as a single string to populate the entity to support entity mapping features within Sentinel. Additionally, if the array is multivalued, we will input a string to indicate this with a unique hash so that matching will not occur.\n",
        "displayName": "Office 365 - Sharepoint File Transfer Above Threshold",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "UserId",
                "identifier": "FullName"
              },
              {
                "columnName": "AccountName",
                "identifier": "Name"
              },
              {
                "columnName": "AccountUPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "ClientIp",
                "identifier": "Address"
              }
            ]
          },
          {
            "entityType": "File",
            "fieldMappings": [
              {
                "columnName": "DirSample",
                "identifier": "Name"
              }
            ]
          }
        ],
        "incidentConfiguration": {
          "createIncident": true,
          "groupingConfiguration": {
            "enabled": true,
            "groupByAlertDetails": [],
            "groupByCustomDetails": [],
            "groupByEntities": [
              "Account"
            ],
            "lookbackDuration": "PT5H",
            "matchingMethod": "Selected",
            "reopenClosedIncident": false
          }
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Global Secure Access/Analytic Rules/Office 365 - sharepoint_file_transfer_folders_above_threshold.yaml",
        "query": "let threshold = 500;\nEnrichedMicrosoft365AuditLogs\n| where Workload has_any(\"SharePoint\", \"OneDrive\") and Operation has_any(\"FileDownloaded\", \"FileSyncDownloadedFull\", \"FileSyncUploadedFull\", \"FileUploaded\")\n| extend EventSource = tostring(parse_json(tostring(AdditionalProperties)).EventSource)\n| extend UserAgent = tostring(parse_json(tostring(AdditionalProperties)).UserAgent)\n| summarize count_distinct_ObjectId = dcount(ObjectId), dirlist = make_set(ObjectId, 10000) by UserId, ClientIp, UserAgent, bin(TimeGenerated, 15m)\n| where count_distinct_ObjectId >= threshold\n| extend DirSample = iff(array_length(dirlist) == 1, tostring(dirlist[0]), strcat(\"SeeDirListField\",\"_\", tostring(hash(tostring(dirlist)))))\n| extend AccountName = tostring(split(UserId, \"@\")[0]), AccountUPNSuffix = tostring(split(UserId, \"@\")[1])\n",
        "queryFrequency": "PT15M",
        "queryPeriod": "PT15M",
        "severity": "Medium",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Exfiltration"
        ],
        "techniques": [
          "T1020"
        ],
        "templateVersion": "1.0.5",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}