Files Copied to USB Drives

Status: available
Severity: high
Time window: 1h
Source: github.com/Azure/Azure-Sentinel

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.

MITRE ATT&CK coverage

Tactic	Techniques
Exfiltration	`T1041` Exfiltration Over C2 Channel

Event coverage

Provider	Event/ActionType	Title
Sysmon	Event ID 11	FileCreate
Security-Auditing	Event ID 4663	An attempt was made to access an object.
Defender-DeviceFileEvents	FileCreated	File created

Rule body kusto

id: 3ab04acf-e0e7-4f7c-8995-748ab4c848c2
name: 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
status: Available
requiredDataConnectors:
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - DeviceEvents
      - DeviceFileEvents
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Exfiltration
relevantTechniques:
  - T1041
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'
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: DeviceName
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: DnsDomain
  - entityType: File
    fieldMappings:
      - identifier: Name
        columnName: FileName
      - identifier: Directory
        columnName: FolderPath
  - entityType: FileHash
    fieldMappings:
      - identifier: Algorithm
        columnName: FileHashAlgorithm
      - identifier: Value
        columnName: SHA256
version: 1.0.0
kind: Scheduled

Stages and Predicates

Let binding: `UsbDriveMount`

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;

The stages below define let FileCreation (the rule's main pipeline source).

Stage 1: `source`

DeviceFileEvents

Stage 2: `where`

| where InitiatingProcessAccountName != "system"

Stage 3: `where`

| where ActionType == "FileCreated"

Stage 4: `where`

| where FolderPath !startswith "C:\\"

Stage 5: `where`

| where FolderPath !startswith "\\"

Stage 6: `project`

| project ReportId,DeviceId,InitiatingProcessAccountDomain,
InitiatingProcessAccountName,InitiatingProcessAccountUpn,
FileName, FolderPath, SHA256, TimeGenerated, SensitivityLabel, IsAzureInfoProtectionApplied

Stage 7: `sort`

| order by DeviceId asc, TimeGenerated desc

The stages below run on FileCreation (the outer pipeline).

Stage 8: `kusto:lookup`

FileCreation
| lookup kind=inner (UsbDriveMount) on DeviceId

Stage 9: `where`

| where FolderPath startswith DriveLetter

Stage 10: `where`

| where TimeGenerated >= MountTime

Stage 11: `partition`

| partition hint.strategy=native by ReportId ( top 1 by MountTime )

Stage 12: `sort`

| order by DeviceId asc, TimeGenerated desc

Stage 13: `extend` (3 consecutive steps)

| extend HostName = iff(DeviceName has '.', substring(DeviceName, 0, indexof(DeviceName, '.')), DeviceName)
| extend DnsDomain = iff(DeviceName has '.', substring(DeviceName, indexof(DeviceName, '.') + 1), "")
| extend FileHashAlgorithm = 'SHA256'

HostName =

ifDeviceName has "."substring(DeviceName, 0, indexof(DeviceName, '.'))

elseDeviceName

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`FolderPath`	starts_with	`C:\\`
`FolderPath`	starts_with	`\\`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`ActionType`	eq	`FileCreated` transforms: `cased` corpus 8 (kusto 8)
`FolderPath`	starts_with	`DriveLetter`
`InitiatingProcessAccountName`	ne	`system` transforms: `cased`
`TimeGenerated`	ge	`MountTime` transforms: `cased`

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

Field	Source
`DeviceId`	`project`
`FileName`	`project`
`FolderPath`	`project`
`InitiatingProcessAccountDomain`	`project`
`InitiatingProcessAccountName`	`project`
`InitiatingProcessAccountUpn`	`project`
`IsAzureInfoProtectionApplied`	`project`
`ReportId`	`project`
`SHA256`	`project`
`SensitivityLabel`	`project`
`TimeGenerated`	`project`
`HostName`	`extend`
`DnsDomain`	`extend`
`FileHashAlgorithm`	`extend`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Files Copied to USB Drives

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Let binding: `UsbDriveMount`

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `project`

Stage 7: `sort`

Stage 8: `kusto:lookup`

Stage 9: `where`

Stage 10: `where`

Stage 11: `partition`

Stage 12: `sort`

Stage 13: `extend` (3 consecutive steps)

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

Files Copied to USB Drives

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Let binding: UsbDriveMount

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: where

Stage 5: where

Stage 6: project

Stage 7: sort

Stage 8: kusto:lookup

Stage 9: where

Stage 10: where

Stage 11: partition

Stage 12: sort

Stage 13: extend (3 consecutive steps)

Exclusions

Indicators

Output fields

Let binding: `UsbDriveMount`

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `where`

Stage 5: `where`

Stage 6: `project`

Stage 7: `sort`

Stage 8: `kusto:lookup`

Stage 9: `where`

Stage 10: `where`

Stage 11: `partition`

Stage 12: `sort`

Stage 13: `extend` (3 consecutive steps)