Exes with double file extension and access summary

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Id	d12580c2-1474-4125-a8a3-553f50d91215
Rulename	Exes with double file extension and access summary
Description	Provides a summary of executable files with double file extensions in SharePoint and the users and IP addresses that have accessed them.
Tactics	DefenseEvasion
Techniques	T1036
Required data connectors	AzureActiveDirectory
Kind	Scheduled
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Global Secure Access/Hunting Queries/double_file_ext_exes.yaml
Version	2.0.1
Arm template	d12580c2-1474-4125-a8a3-553f50d91215.json

KQL

let known_ext = dynamic(["lnk", "log", "option", "config", "manifest", "partial"]);
let excluded_users = dynamic(["app@sharepoint"]);
EnrichedMicrosoft365AuditLogs
| where RecordType == "SharePointFileOperation" and isnotempty(ObjectId)
| where ObjectId has ".exe." 
    and not(ObjectId endswith ".lnk") 
    and not(ObjectId endswith ".log") 
    and not(ObjectId endswith ".option") 
    and not(ObjectId endswith ".config") 
    and not(ObjectId endswith ".manifest") 
    and not(ObjectId endswith ".partial")
| extend Extension = extract("[^.]*\\.[^.]*$", 0, ObjectId)
| extend SourceFileName = tostring(parse_json(tostring(AdditionalProperties)).SourceFileName)
| join kind=leftouter (
    EnrichedMicrosoft365AuditLogs
    | where RecordType == "SharePointFileOperation" and (Operation == "FileDownloaded" or Operation == "FileAccessed")
    | where not(ObjectId endswith ".lnk") 
        and not(ObjectId endswith ".log") 
        and not(ObjectId endswith ".option") 
        and not(ObjectId endswith ".config") 
        and not(ObjectId endswith ".manifest") 
        and not(ObjectId endswith ".partial")
) on ObjectId
| where UserId1 !in (excluded_users)
| extend userBag = bag_pack("UserId", UserId1, "ClientIp", ClientIp1)
| summarize make_set(UserId1, 10000), userBag = make_bag(userBag), UploadTime = max(TimeGenerated) by UserId, ObjectId, SourceFileName, Extension
| extend NumberOfUsers = array_length(bag_keys(userBag))
| project UploadTime, Uploader = UserId, FileLocation = ObjectId, FileName = SourceFileName, AccessedBy = userBag, Extension, NumberOfUsers
| extend UploaderName = tostring(split(Uploader, "@")[0]), UploaderUPNSuffix = tostring(split(Uploader, "@")[1])

YAML

description: |
  'Provides a summary of executable files with double file extensions in SharePoint 
   and the users and IP addresses that have accessed them.'  
entityMappings:
- fieldMappings:
  - columnName: UploaderName
    identifier: Name
  - columnName: UploaderUPNSuffix
    identifier: UPNSuffix
  entityType: Account
kind: Scheduled
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - EnrichedMicrosoft365AuditLogs
query: |
  let known_ext = dynamic(["lnk", "log", "option", "config", "manifest", "partial"]);
  let excluded_users = dynamic(["app@sharepoint"]);
  EnrichedMicrosoft365AuditLogs
  | where RecordType == "SharePointFileOperation" and isnotempty(ObjectId)
  | where ObjectId has ".exe." 
      and not(ObjectId endswith ".lnk") 
      and not(ObjectId endswith ".log") 
      and not(ObjectId endswith ".option") 
      and not(ObjectId endswith ".config") 
      and not(ObjectId endswith ".manifest") 
      and not(ObjectId endswith ".partial")
  | extend Extension = extract("[^.]*\\.[^.]*$", 0, ObjectId)
  | extend SourceFileName = tostring(parse_json(tostring(AdditionalProperties)).SourceFileName)
  | join kind=leftouter (
      EnrichedMicrosoft365AuditLogs
      | where RecordType == "SharePointFileOperation" and (Operation == "FileDownloaded" or Operation == "FileAccessed")
      | where not(ObjectId endswith ".lnk") 
          and not(ObjectId endswith ".log") 
          and not(ObjectId endswith ".option") 
          and not(ObjectId endswith ".config") 
          and not(ObjectId endswith ".manifest") 
          and not(ObjectId endswith ".partial")
  ) on ObjectId
  | where UserId1 !in (excluded_users)
  | extend userBag = bag_pack("UserId", UserId1, "ClientIp", ClientIp1)
  | summarize make_set(UserId1, 10000), userBag = make_bag(userBag), UploadTime = max(TimeGenerated) by UserId, ObjectId, SourceFileName, Extension
  | extend NumberOfUsers = array_length(bag_keys(userBag))
  | project UploadTime, Uploader = UserId, FileLocation = ObjectId, FileName = SourceFileName, AccessedBy = userBag, Extension, NumberOfUsers
  | extend UploaderName = tostring(split(Uploader, "@")[0]), UploaderUPNSuffix = tostring(split(Uploader, "@")[1])  
version: 2.0.1
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Global Secure Access/Hunting Queries/double_file_ext_exes.yaml
relevantTechniques:
- T1036
tactics:
- DefenseEvasion
id: d12580c2-1474-4125-a8a3-553f50d91215
name: Exes with double file extension and access summary

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/d12580c2-1474-4125-a8a3-553f50d91215')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/d12580c2-1474-4125-a8a3-553f50d91215')]",
      "properties": {
        "alertRuleTemplateName": "d12580c2-1474-4125-a8a3-553f50d91215",
        "customDetails": null,
        "description": "'Provides a summary of executable files with double file extensions in SharePoint \n and the users and IP addresses that have accessed them.'\n",
        "displayName": "Exes with double file extension and access summary",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "UploaderName",
                "identifier": "Name"
              },
              {
                "columnName": "UploaderUPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Global Secure Access/Hunting Queries/double_file_ext_exes.yaml",
        "query": "let known_ext = dynamic([\"lnk\", \"log\", \"option\", \"config\", \"manifest\", \"partial\"]);\nlet excluded_users = dynamic([\"app@sharepoint\"]);\nEnrichedMicrosoft365AuditLogs\n| where RecordType == \"SharePointFileOperation\" and isnotempty(ObjectId)\n| where ObjectId has \".exe.\" \n    and not(ObjectId endswith \".lnk\") \n    and not(ObjectId endswith \".log\") \n    and not(ObjectId endswith \".option\") \n    and not(ObjectId endswith \".config\") \n    and not(ObjectId endswith \".manifest\") \n    and not(ObjectId endswith \".partial\")\n| extend Extension = extract(\"[^.]*\\\\.[^.]*$\", 0, ObjectId)\n| extend SourceFileName = tostring(parse_json(tostring(AdditionalProperties)).SourceFileName)\n| join kind=leftouter (\n    EnrichedMicrosoft365AuditLogs\n    | where RecordType == \"SharePointFileOperation\" and (Operation == \"FileDownloaded\" or Operation == \"FileAccessed\")\n    | where not(ObjectId endswith \".lnk\") \n        and not(ObjectId endswith \".log\") \n        and not(ObjectId endswith \".option\") \n        and not(ObjectId endswith \".config\") \n        and not(ObjectId endswith \".manifest\") \n        and not(ObjectId endswith \".partial\")\n) on ObjectId\n| where UserId1 !in (excluded_users)\n| extend userBag = bag_pack(\"UserId\", UserId1, \"ClientIp\", ClientIp1)\n| summarize make_set(UserId1, 10000), userBag = make_bag(userBag), UploadTime = max(TimeGenerated) by UserId, ObjectId, SourceFileName, Extension\n| extend NumberOfUsers = array_length(bag_keys(userBag))\n| project UploadTime, Uploader = UserId, FileLocation = ObjectId, FileName = SourceFileName, AccessedBy = userBag, Extension, NumberOfUsers\n| extend UploaderName = tostring(split(Uploader, \"@\")[0]), UploaderUPNSuffix = tostring(split(Uploader, \"@\")[1])\n",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "DefenseEvasion"
        ],
        "techniques": [
          "T1036"
        ],
        "templateVersion": "2.0.1"
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}