StealthTalk - Login outside work zone

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

Identifies a single StealthTalk authentication originating from a country or city that does not match the user's assigned (expected) geographic zone. Each individual mismatch is treated as an incident - there is no aggregation threshold, since a single login from an unexpected country is high-confidence evidence of a credential issue. An incident fires when LoginCountry differs from AssignedCountry OR LoginCity differs from AssignedCity. Source IPv4, raw event ID, and both the observed and expected geo-locations are surfaced as entities and custom details for the SOC analyst.

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1078` Valid Accounts
Stealth	`T1078` Valid Accounts

Rule body

id: a7c3e9b1-4f5d-4e2a-9b8c-1d2e3f4a5b6c
name: StealthTalk - Login outside work zone
description: |
  Identifies a single StealthTalk authentication originating from a country or city that does
  not match the user's assigned (expected) geographic zone. Each individual mismatch is
  treated as an incident - there is no aggregation threshold, since a single login from an
  unexpected country is high-confidence evidence of a credential issue.

  An incident fires when LoginCountry differs from AssignedCountry OR LoginCity differs
  from AssignedCity. Source IPv4, raw event ID, and both the observed and expected
  geo-locations are surfaced as entities and custom details for the SOC analyst.
severity: High
requiredDataConnectors:
  - connectorId: StealthTalkAnomalousAuth
    dataTypes:
      - StealthTalkAnomalousAuth_CL
queryFrequency: 15m
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
status: Available
tactics:
  - InitialAccess
  - DefenseEvasion
  - CredentialAccess
relevantTechniques:
  - T1078
query: |
  let LookbackPeriod = 1h;
  StealthTalkAnomalousAuth_CL
  | where TimeGenerated >= ago(LookbackPeriod)
  | where EventType == "GeoAnomalyLogin"
  | where LoginCountry != AssignedCountry
       or LoginCity    != AssignedCity
  | extend
      CountryMismatch = LoginCountry != AssignedCountry,
      CityMismatch    = LoginCity    != AssignedCity,
      AlertName       = "LoginOutsideWorkZone",
      AlertDetails    = strcat(
          "User ", UserId,
          " logged in from ", LoginCity, " (", LoginCountry, ")",
          " - assigned zone: ", AssignedCity, " (", AssignedCountry, ").",
          " Source IP: ", IpAddress, ".",
          " Country mismatch: ", tostring(LoginCountry != AssignedCountry), ".",
          " City mismatch: ", tostring(LoginCity != AssignedCity), "."
      )
  | project
      TimeGenerated, UserId, DeviceId,
      LoginCountry, LoginCity, AssignedCountry, AssignedCity,
      CountryMismatch, CityMismatch, IpAddress,
      AppVersion, RawEventId, AlertName, AlertDetails
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: UserId
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: DeviceId
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IpAddress
customDetails:
  LoginCountry: LoginCountry
  LoginCity: LoginCity
  AssignedCountry: AssignedCountry
  AssignedCity: AssignedCity
  CountryMismatch: CountryMismatch
  CityMismatch: CityMismatch
  AppVersion: AppVersion
  EventReference: RawEventId
alertDetailsOverride:
  alertDisplayNameFormat: 'StealthTalk: Login Outside Work Zone - {{UserId}} from {{LoginCity}} ({{LoginCountry}})'
  alertDescriptionFormat: '{{AlertDetails}}'
incidentConfiguration:
  createIncident: true
  groupingConfiguration:
    enabled: true
    reopenClosedIncident: false
    lookbackDuration: 5h
    matchingMethod: Selected
    groupByEntities:
      - Account
suppressionEnabled: false
suppressionDuration: 1h
version: 1.0.0
kind: Scheduled

Stages and Predicates

Parameters

let LookbackPeriod = 1h;

Stage 1: `source`

StealthTalkAnomalousAuth_CL

Stage 2: `where`

| where TimeGenerated >= ago(LookbackPeriod)

Stage 3: `where`

| where EventType == "GeoAnomalyLogin"

Stage 4: `where`

| where LoginCountry != AssignedCountry
     or LoginCity    != AssignedCity

Stage 5: `extend`

| extend
    CountryMismatch = LoginCountry != AssignedCountry,
    CityMismatch    = LoginCity    != AssignedCity,
    AlertName       = "LoginOutsideWorkZone",
    AlertDetails    = strcat(
        "User ", UserId,
        " logged in from ", LoginCity, " (", LoginCountry, ")",
        " - assigned zone: ", AssignedCity, " (", AssignedCountry, ").",
        " Source IP: ", IpAddress, ".",
        " Country mismatch: ", tostring(LoginCountry != AssignedCountry), ".",
        " City mismatch: ", tostring(LoginCity != AssignedCity), "."
    )

Stage 6: `project`

| project
    TimeGenerated, UserId, DeviceId,
    LoginCountry, LoginCity, AssignedCountry, AssignedCity,
    CountryMismatch, CityMismatch, IpAddress,
    AppVersion, RawEventId, AlertName, AlertDetails

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`EventType`	eq	`GeoAnomalyLogin`	`field:"EventType" kind:eq value:"GeoAnomalyLogin"`
`LoginCity`	cross_field_compare	`AssignedCity` transforms: `op:ne`	`field:"LoginCity" kind:cross_field_compare value:"AssignedCity"`
`LoginCountry`	cross_field_compare	`AssignedCountry` transforms: `op:ne`	`field:"LoginCountry" kind:cross_field_compare value:"AssignedCountry"`

Output fields

These fields are emitted when the rule matches.

Field	Source
`AlertDetails`	`project`
`AlertName`	`project`
`AppVersion`	`project`
`AssignedCity`	`project`
`AssignedCountry`	`project`
`CityMismatch`	`project`
`CountryMismatch`	`project`
`DeviceId`	`project`
`IpAddress`	`project`
`LoginCity`	`project`
`LoginCountry`	`project`
`RawEventId`	`project`
`TimeGenerated`	`project`
`UserId`	`project`

StealthTalk - Login outside work zone

MITRE ATT&CK coverage

Rule body

Stages and Predicates

Parameters

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: where

Stage 5: extend

Stage 6: project