Dataverse - Terminated employee exfiltration to USB drive

Status: available
Severity: high
Time window: 14d
Group by: FileOriginUrl, InitiatingProcessAccountUpn, InstanceUrl, UserId, UserPrincipalName
Source: github.com/Azure/Azure-Sentinel

Identifies files downloaded from Dataverse by departing or terminated employees which are copied to USB mounted drives.

MITRE ATT&CK coverage

Tactic	Techniques
Exfiltration	`T1052` Exfiltration Over Physical Medium

Rule body kusto

id: c5e75cb6-cea0-49c2-a998-da414035aac1
kind: Scheduled
name: Dataverse - Terminated employee exfiltration to USB drive
description: Identifies files downloaded from Dataverse by departing or terminated
  employees which are copied to USB mounted drives.
severity: High
status: Available
requiredDataConnectors:
  - connectorId: Dataverse
    dataTypes:
      - DataverseActivity
  - connectorId: MicrosoftThreatProtection
    dataTypes:
      - DeviceInfo
      - DeviceEvents
      - DeviceFileEvents
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Exfiltration
relevantTechniques:
  - T1052
query: |
  let drive_mount_lookback = 14d;
  let query_frequency = 1h;
  DataverseActivity
  | distinct InstanceUrl
  | join kind=inner (DeviceFileEvents
      | where TimeGenerated >= ago(query_frequency))
      on $left.InstanceUrl == $right.FileOriginUrl
  | join kind=inner (MSBizAppsTerminatedEmployees()) on $left.InitiatingProcessAccountUpn == $right.UserPrincipalName
  | join kind=inner (DeviceEvents
      | where TimeGenerated >= ago(drive_mount_lookback)
      | where ActionType == "UsbDriveMounted"
      | extend DriveLetter = tostring(AdditionalFields.DriveLetter)
      | summarize MountedDriveLetters = make_set(DriveLetter, 26) by DeviceId, DeviceName)
      on DeviceId
  | extend TargetDriveLetter = tostring(split(FolderPath, "\\")[0])
  | where set_has_element(MountedDriveLetters, TargetDriveLetter)
  | join kind=inner (DeviceInfo
      | summarize arg_max(TimeGenerated, DeviceId, PublicIP) by DeviceName)
      on DeviceId
  | project-rename
      UserId = UserPrincipalName
  | summarize LatestEvent = arg_max(TimeGenerated, *), Files = make_set(FileName, 100) by UserId, InstanceUrl
  | extend
      CloudAppId = int(32780),
      AccountName = tostring(split(UserId, '@')[0]),
      UPNSuffix = tostring(split(UserId, '@')[1])
  | project
      LatestEvent,
      UserId,
      PublicIP,
      Files,
      InstanceUrl,
      CloudAppId,
      AccountName,
      UPNSuffix
eventGroupingSettings:
  aggregationKind: AlertPerResult
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: UPNSuffix
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: PublicIP
  - entityType: CloudApplication
    fieldMappings:
      - identifier: AppId
        columnName: CloudAppId
      - identifier: InstanceName
        columnName: InstanceUrl
alertDetailsOverride:
  alertDisplayNameFormat: Dataverse - terminated user copied files from {{InstanceUrl}}
    to USB
  alertDescriptionFormat: '{{UserId}} , on the TerminatedUsers watchlist, was found
    to copy files to a USB mounted drive.'
customDetails: {}
version: 3.2.0

Stages and Predicates

Parameters

let drive_mount_lookback = 14d;
let query_frequency = 1h;

Stage 1: `source`

DataverseActivity

Stage 2: `distinct`

| distinct InstanceUrl

Stage 3: `join`

| join kind=inner (DeviceFileEvents
    | where TimeGenerated >= ago(query_frequency))
    on $left.InstanceUrl == $right.FileOriginUrl

Stage 4: `join`

| join kind=inner (MSBizAppsTerminatedEmployees()) on $left.InitiatingProcessAccountUpn == $right.UserPrincipalName

Stage 5: `join`

| join kind=inner (DeviceEvents
    | where TimeGenerated >= ago(drive_mount_lookback)
    | where ActionType == "UsbDriveMounted"
    | extend DriveLetter = tostring(AdditionalFields.DriveLetter)
    | summarize MountedDriveLetters = make_set(DriveLetter, 26) by DeviceId, DeviceName)
    on DeviceId

Stage 6: `extend`

| extend TargetDriveLetter = tostring(split(FolderPath, "\\")[0])

Stage 7: `where`

| where set_has_element(MountedDriveLetters, TargetDriveLetter)

Stage 8: `join`

| join kind=inner (DeviceInfo
    | summarize arg_max(TimeGenerated, DeviceId, PublicIP) by DeviceName)
    on DeviceId

Stage 9: `project-rename`

| project-rename
    UserId = UserPrincipalName

Stage 10: `summarize`

| summarize LatestEvent = arg_max(TimeGenerated, *), Files = make_set(FileName, 100) by UserId, InstanceUrl

Stage 11: `extend`

| extend
    CloudAppId = int(32780),
    AccountName = tostring(split(UserId, '@')[0]),
    UPNSuffix = tostring(split(UserId, '@')[1])

Stage 12: `project`

| project
    LatestEvent,
    UserId,
    PublicIP,
    Files,
    InstanceUrl,
    CloudAppId,
    AccountName,
    UPNSuffix

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	`UsbDriveMounted` transforms: `cased` corpus 2 (kusto 2)
`TargetDriveLetter`	in	`MountedDriveLetters` transforms: `set_has_element`

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
`AccountName`	`project`
`CloudAppId`	`project`
`Files`	`project`
`InstanceUrl`	`project`
`LatestEvent`	`project`
`PublicIP`	`project`
`UPNSuffix`	`project`
`UserId`	`project`

`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)

Dataverse - Terminated employee exfiltration to USB drive

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: `source`

Stage 2: `distinct`

Stage 3: `join`

Stage 4: `join`

Stage 5: `join`

Stage 6: `extend`

Stage 7: `where`

Stage 8: `join`

Stage 9: `project-rename`

Stage 10: `summarize`

Stage 11: `extend`

Stage 12: `project`

Indicators

Output fields

Keyboard shortcuts

Search operators

Dataverse - Terminated employee exfiltration to USB drive

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: source

Stage 2: distinct

Stage 3: join

Stage 4: join

Stage 5: join

Stage 6: extend

Stage 7: where

Stage 8: join

Stage 9: project-rename

Stage 10: summarize

Stage 11: extend

Stage 12: project

Indicators

Output fields

Stage 1: `source`

Stage 2: `distinct`

Stage 3: `join`

Stage 4: `join`

Stage 5: `join`

Stage 6: `extend`

Stage 7: `where`

Stage 8: `join`

Stage 9: `project-rename`

Stage 10: `summarize`

Stage 11: `extend`

Stage 12: `project`