Microsoft Sentinel Analytic Rules
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Office365 Sharepoint File transfer above threshold

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Id8a547285-801c-4290-aa2e-5e7e20ca157d
RulenameOffice365 Sharepoint File transfer above threshold
DescriptionIdentifies Office365 Sharepoint File Transfers with distinct folder count above certain threshold in a 15min 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.
SeverityMedium
TacticsExfiltration
TechniquesT1020
Required data connectorsOffice365
KindScheduled
Query frequency15m
Query period15m
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft 365/Analytic Rules/sharepoint_file_transfer_folders_above_threshold.yaml
Version1.0.4
Arm template8a547285-801c-4290-aa2e-5e7e20ca157d.json
Deploy To Azure
let threshold = 500;
OfficeActivity
| where EventSource == "SharePoint" and OfficeWorkload has_any("SharePoint", "OneDrive") and Operation has_any ("FileDownloaded", "FileSyncDownloadedFull", "FileSyncUploadedFull", "FileUploaded")
| summarize count_distinct_SourceRelativeUrl=dcount(SourceRelativeUrl), dirlist=make_set(SourceRelativeUrl, 10000) by UserId,ClientIP,UserAgent,bin(TimeGenerated, 15m)
| where count_distinct_SourceRelativeUrl >= 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])
triggerOperator: gt
tactics:
- Exfiltration
queryPeriod: 15m
kind: Scheduled
relevantTechniques:
- T1020
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft 365/Analytic Rules/sharepoint_file_transfer_folders_above_threshold.yaml
queryFrequency: 15m
customDetails:
  TransferCount: count_distinct_SourceRelativeUrl
  FilesList: dirlist
description: |
  'Identifies Office365 Sharepoint File Transfers with distinct folder count above certain threshold in a 15min 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.'  
requiredDataConnectors:
- dataTypes:
  - OfficeActivity (SharePoint)
  connectorId: Office365
version: 1.0.4
incidentConfiguration:
  createIncident: true
  groupingConfiguration:
    enabled: true
    reopenClosedIncident: false
    groupByAlertDetails: []
    groupByCustomDetails: []
    matchingMethod: Selected
    lookbackDuration: 5h
    groupByEntities:
    - Account
triggerThreshold: 0
severity: Medium
id: 8a547285-801c-4290-aa2e-5e7e20ca157d
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
name: Office365 Sharepoint File transfer above threshold
query: |
  let threshold = 500;
  OfficeActivity
  | where EventSource == "SharePoint" and OfficeWorkload has_any("SharePoint", "OneDrive") and Operation has_any ("FileDownloaded", "FileSyncDownloadedFull", "FileSyncUploadedFull", "FileUploaded")
  | summarize count_distinct_SourceRelativeUrl=dcount(SourceRelativeUrl), dirlist=make_set(SourceRelativeUrl, 10000) by UserId,ClientIP,UserAgent,bin(TimeGenerated, 15m)
  | where count_distinct_SourceRelativeUrl >= 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])  
{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2023-02-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/8a547285-801c-4290-aa2e-5e7e20ca157d')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/8a547285-801c-4290-aa2e-5e7e20ca157d')]",
      "properties": {
        "alertRuleTemplateName": "8a547285-801c-4290-aa2e-5e7e20ca157d",
        "customDetails": {
          "FilesList": "dirlist",
          "TransferCount": "count_distinct_SourceRelativeUrl"
        },
        "description": "'Identifies Office365 Sharepoint File Transfers with distinct folder count above certain threshold in a 15min time period.\n 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.'\n",
        "displayName": "Office365 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/Microsoft 365/Analytic Rules/sharepoint_file_transfer_folders_above_threshold.yaml",
        "query": "let threshold = 500;\nOfficeActivity\n| where EventSource == \"SharePoint\" and OfficeWorkload has_any(\"SharePoint\", \"OneDrive\") and Operation has_any (\"FileDownloaded\", \"FileSyncDownloadedFull\", \"FileSyncUploadedFull\", \"FileUploaded\")\n| summarize count_distinct_SourceRelativeUrl=dcount(SourceRelativeUrl), dirlist=make_set(SourceRelativeUrl, 10000) by UserId,ClientIP,UserAgent,bin(TimeGenerated, 15m)\n| where count_distinct_SourceRelativeUrl >= 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",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Exfiltration"
        ],
        "techniques": [
          "T1020"
        ],
        "templateVersion": "1.0.4",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}