Detection rules › Kusto

Box - Item shared to external entity

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

'Detects when an item was shared to external entity.'

MITRE ATT&CK coverage

TacticTechniques
Exfiltration

Rule body

id: 3b803560-f8a6-4db4-89cb-617d89724ba1
name: Box - Item shared to external entity
description: |
  'Detects when an item was shared to external entity.'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: BoxDataConnector
    dataTypes:
      - BoxEvents_CL
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Exfiltration
relevantTechniques:
  - T1537
query: |
  BoxEvents
  | where EventType =~ 'COLLABORATION_INVITE'
  | extend corp_domain = tolower(extract(@'@(.*)', 1, SrcUserUpn))
  | extend accessibleby_domain = tolower(extract(@'@(.*)', 1, AccessibleByLogin))
  | where corp_domain != accessibleby_domain
  | extend AccountCustomEntity = SrcUserUpn
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: AccountCustomEntity
version: 1.0.0
kind: Scheduled

Stages and Predicates

Stage 1: source

BoxEvents

Stage 2: where

| where EventType =~ 'COLLABORATION_INVITE'

Stage 3: extend

| extend corp_domain = tolower(extract(@'@(.*)', 1, SrcUserUpn))

Stage 4: extend

| extend accessibleby_domain = tolower(extract(@'@(.*)', 1, AccessibleByLogin))

Stage 5: where

| where corp_domain != accessibleby_domain

Stage 6: extend

| extend AccountCustomEntity = SrcUserUpn

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
EventTypeeq
  • COLLABORATION_INVITE
field:"EventType" kind:eq value:"COLLABORATION_INVITE"
corp_domaincross_field_compare
  • accessibleby_domain transforms: op:ne
field:"corp_domain" kind:cross_field_compare value:"accessibleby_domain"

Output fields

These fields are emitted when the rule matches.

FieldSource
corp_domainextend
accessibleby_domainextend
AccountCustomEntityextend