Files Copied to USB Drives

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Id	3ab04acf-e0e7-4f7c-8995-748ab4c848c2
Rulename	Files Copied to USB Drives
Description	This query lists files copied to USB external drives with USB drive information based on FileCreated events associated with most recent USBDriveMount events befor file creations. But be aware that Advanced Hunting is not monitoring all the file types.
Severity	High
Tactics	Exfiltration
Techniques	T1041
Required data connectors	MicrosoftThreatProtection
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Defender XDR/Analytic Rules/Exfiltration/FilesCopiedToUSBDrives.yaml
Version	1.0.0
Arm template	3ab04acf-e0e7-4f7c-8995-748ab4c848c2.json

KQL

let UsbDriveMount = DeviceEvents
| where ActionType=="UsbDriveMounted"
| extend ParsedFields=parse_json(AdditionalFields)
| project DeviceId, DeviceName, DriveLetter=ParsedFields.DriveLetter, MountTime=TimeGenerated,
ProductName=ParsedFields.ProductName,SerialNumber=ParsedFields.SerialNumber,Manufacturer=ParsedFields.Manufacturer
| order by DeviceId asc, MountTime desc;
let FileCreation = DeviceFileEvents
| where InitiatingProcessAccountName != "system"
| where ActionType == "FileCreated"
| where FolderPath !startswith "C:\\"
| where FolderPath !startswith "\\"
| project ReportId,DeviceId,InitiatingProcessAccountDomain,
InitiatingProcessAccountName,InitiatingProcessAccountUpn,
FileName, FolderPath, SHA256, TimeGenerated, SensitivityLabel, IsAzureInfoProtectionApplied
| order by DeviceId asc, TimeGenerated desc;
FileCreation | lookup kind=inner (UsbDriveMount) on DeviceId
| where FolderPath startswith DriveLetter
| where TimeGenerated >= MountTime
| partition hint.strategy=native by ReportId ( top 1 by MountTime )
| order by DeviceId asc, TimeGenerated desc
| extend HostName = iff(DeviceName has '.', substring(DeviceName, 0, indexof(DeviceName, '.')), DeviceName)
| extend DnsDomain = iff(DeviceName has '.', substring(DeviceName, indexof(DeviceName, '.') + 1), "")
| extend FileHashAlgorithm = 'SHA256'

YAML

name: Files Copied to USB Drives
relevantTechniques:
- T1041
id: 3ab04acf-e0e7-4f7c-8995-748ab4c848c2
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Defender XDR/Analytic Rules/Exfiltration/FilesCopiedToUSBDrives.yaml
requiredDataConnectors:
- dataTypes:
  - DeviceEvents
  - DeviceFileEvents
  connectorId: MicrosoftThreatProtection
version: 1.0.0
severity: High
triggerThreshold: 0
queryPeriod: 1h
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: DeviceName
  - identifier: HostName
    columnName: HostName
  - identifier: DnsDomain
    columnName: DnsDomain
  entityType: Host
- fieldMappings:
  - identifier: Name
    columnName: FileName
  - identifier: Directory
    columnName: FolderPath
  entityType: File
- fieldMappings:
  - identifier: Algorithm
    columnName: FileHashAlgorithm
  - identifier: Value
    columnName: SHA256
  entityType: FileHash
queryFrequency: 1h
status: Available
query: |
  let UsbDriveMount = DeviceEvents
  | where ActionType=="UsbDriveMounted"
  | extend ParsedFields=parse_json(AdditionalFields)
  | project DeviceId, DeviceName, DriveLetter=ParsedFields.DriveLetter, MountTime=TimeGenerated,
  ProductName=ParsedFields.ProductName,SerialNumber=ParsedFields.SerialNumber,Manufacturer=ParsedFields.Manufacturer
  | order by DeviceId asc, MountTime desc;
  let FileCreation = DeviceFileEvents
  | where InitiatingProcessAccountName != "system"
  | where ActionType == "FileCreated"
  | where FolderPath !startswith "C:\\"
  | where FolderPath !startswith "\\"
  | project ReportId,DeviceId,InitiatingProcessAccountDomain,
  InitiatingProcessAccountName,InitiatingProcessAccountUpn,
  FileName, FolderPath, SHA256, TimeGenerated, SensitivityLabel, IsAzureInfoProtectionApplied
  | order by DeviceId asc, TimeGenerated desc;
  FileCreation | lookup kind=inner (UsbDriveMount) on DeviceId
  | where FolderPath startswith DriveLetter
  | where TimeGenerated >= MountTime
  | partition hint.strategy=native by ReportId ( top 1 by MountTime )
  | order by DeviceId asc, TimeGenerated desc
  | extend HostName = iff(DeviceName has '.', substring(DeviceName, 0, indexof(DeviceName, '.')), DeviceName)
  | extend DnsDomain = iff(DeviceName has '.', substring(DeviceName, indexof(DeviceName, '.') + 1), "")
  | extend FileHashAlgorithm = 'SHA256'  
tactics:
- Exfiltration
kind: Scheduled
description: |
    This query lists files copied to USB external drives with USB drive information based on FileCreated events associated with most recent USBDriveMount events befor file creations. But be aware that Advanced Hunting is not monitoring all the file types.
triggerOperator: gt

ARM