StealthTalk - Multi new devices registration

Status: available
Severity: medium
Time window: 1d
Group by: UserId
Source: github.com/Azure/Azure-Sentinel

Identifies a single StealthTalk user registering two or more previously-unseen devices within a 24-hour window. Sudden registration of multiple new devices is a strong indicator of account takeover (an attacker enrolling their own device after credential theft) or device-farm abuse. The rule fires when a user produces two or more distinct NewDeviceId values within the lookback window, regardless of operating system. Look at the OSList custom detail to spot cross-platform patterns (e.g. an iOS-only user suddenly enrolling an Android device).

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1078` Valid Accounts
Persistence	`T1078` Valid Accounts, `T1098` Account Manipulation
Stealth	`T1078` Valid Accounts

Rule body kusto

id: f9d4c2a8-1b6e-4a3f-9c7d-8e2b1a3c5d7e
name: StealthTalk - Multi new devices registration
description: |
  Identifies a single StealthTalk user registering two or more previously-unseen devices within
  a 24-hour window. Sudden registration of multiple new devices is a strong indicator of
  account takeover (an attacker enrolling their own device after credential theft) or
  device-farm abuse.

  The rule fires when a user produces two or more distinct NewDeviceId values within the
  lookback window, regardless of operating system. Look at the OSList custom detail to spot
  cross-platform patterns (e.g. an iOS-only user suddenly enrolling an Android device).
severity: Medium
requiredDataConnectors:
  - connectorId: StealthTalkAnomalousAuth
    dataTypes:
      - StealthTalkAnomalousAuth_CL
queryFrequency: 30m
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
status: Available
tactics:
  - Persistence
  - InitialAccess
  - DefenseEvasion
relevantTechniques:
  - T1078
  - T1098
query: |
  let LookbackPeriod = 24h;
  let MinNewDevices  = 2;
  StealthTalkAnomalousAuth_CL
  | where TimeGenerated >= ago(LookbackPeriod)
  | where EventType == "NewDeviceLogin"
  | summarize
      NewDeviceCount  = dcount(NewDeviceId),
      NewDevices      = make_set(NewDeviceId),
      NewDeviceOSList = make_set(NewDeviceOS),
      FirstSeen       = min(TimeGenerated),
      LastSeen        = max(TimeGenerated),
      AppVersions     = make_set(AppVersion)
    by UserId
  | where NewDeviceCount >= MinNewDevices
  | extend
      AlertName    = "MultiNewDevicesRegistration",
      AlertDetails = strcat(
          "User ", UserId,
          " registered ", NewDeviceCount, " new devices within 24 hours.",
          " Device IDs: ", tostring(NewDevices), ".",
          " Operating systems: ", tostring(NewDeviceOSList), "."
      )
  | project
      TimeGenerated = LastSeen,
      UserId, NewDeviceCount, NewDevices, NewDeviceOSList,
      FirstSeen, LastSeen, AppVersions, AlertName, AlertDetails
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: UserId
customDetails:
  NewDeviceCount: NewDeviceCount
  NewDevices: NewDevices
  NewDeviceOSList: NewDeviceOSList
  FirstSeen: FirstSeen
  LastSeen: LastSeen
alertDetailsOverride:
  alertDisplayNameFormat: 'StealthTalk: Multi New Devices - {{UserId}} ({{NewDeviceCount}} new devices)'
  alertDescriptionFormat: '{{AlertDetails}}'
incidentConfiguration:
  createIncident: true
  groupingConfiguration:
    enabled: true
    reopenClosedIncident: false
    lookbackDuration: 5h
    matchingMethod: Selected
    groupByEntities:
      - Account
suppressionEnabled: false
suppressionDuration: 5h
version: 1.0.0
kind: Scheduled

Stages and Predicates

Parameters

let LookbackPeriod = 24h;
let MinNewDevices = 2;

Stage 1: `source`

StealthTalkAnomalousAuth_CL

Stage 2: `where`

| where TimeGenerated >= ago(LookbackPeriod)

Stage 3: `where`

| where EventType == "NewDeviceLogin"

Stage 4: `summarize`

| summarize
    NewDeviceCount  = dcount(NewDeviceId),
    NewDevices      = make_set(NewDeviceId),
    NewDeviceOSList = make_set(NewDeviceOS),
    FirstSeen       = min(TimeGenerated),
    LastSeen        = max(TimeGenerated),
    AppVersions     = make_set(AppVersion)
  by UserId

Threshold: ge 2

Stage 5: `where`

| where NewDeviceCount >= MinNewDevices

Stage 6: `extend`

| extend
    AlertName    = "MultiNewDevicesRegistration",
    AlertDetails = strcat(
        "User ", UserId,
        " registered ", NewDeviceCount, " new devices within 24 hours.",
        " Device IDs: ", tostring(NewDevices), ".",
        " Operating systems: ", tostring(NewDeviceOSList), "."
    )

Stage 7: `project`

| project
    TimeGenerated = LastSeen,
    UserId, NewDeviceCount, NewDevices, NewDeviceOSList,
    FirstSeen, LastSeen, AppVersions, AlertName, AlertDetails

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
`EventType`	eq	`NewDeviceLogin` transforms: `cased`
`NewDeviceCount`	ge	`2` 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
`AlertDetails`	`project`
`AlertName`	`project`
`AppVersions`	`project`
`FirstSeen`	`project`
`LastSeen`	`project`
`NewDeviceCount`	`project`
`NewDeviceOSList`	`project`
`NewDevices`	`project`
`TimeGenerated`	`project`
`UserId`	`project`

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`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)

StealthTalk - Multi new devices registration

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `summarize`

Stage 5: `where`

Stage 6: `extend`

Stage 7: `project`

Indicators

Output fields

Keyboard shortcuts

Search operators

StealthTalk - Multi new devices registration

MITRE ATT&CK coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: summarize

Stage 5: where

Stage 6: extend

Stage 7: project

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `summarize`

Stage 5: `where`

Stage 6: `extend`

Stage 7: `project`