Detection rules › Kusto
Box - New external user
'Detects when new user created with SourceLogin containing non-corporate domain.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1078 Valid Accounts |
| Persistence | T1078 Valid Accounts |
Rule body kusto
id: fd36ac88-cd92-4137-aa23-37a3648621fa
name: Box - New external user
description: |
'Detects when new user created with SourceLogin containing non-corporate domain.'
severity: Medium
status: Available
requiredDataConnectors:
- connectorId: BoxDataConnector
dataTypes:
- BoxEvents_CL
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
- InitialAccess
- Persistence
relevantTechniques:
- T1078
query: |
BoxEvents
| where EventType =~ 'NEW_USER'
| extend corp_domain = extract(@'@(.*)', 1, SourceLogin)
| extend new_domain = tolower(extract(@'@(.*)', 1, SourceLogin))
| where corp_domain != new_domain
| extend AccountCustomEntity = SourceLogin
| extend IPCustomEntity = SrcIpAddr
entityMappings:
- entityType: Account
fieldMappings:
- identifier: FullName
columnName: AccountCustomEntity
- entityType: IP
fieldMappings:
- identifier: Address
columnName: IPCustomEntity
version: 1.0.0
kind: Scheduled
Stages and Predicates
Stage 1: source
BoxEvents
Stage 2: where
| where EventType =~ 'NEW_USER'
Stage 3: extend
| extend corp_domain = extract(@'@(.*)', 1, SourceLogin)
Stage 4: extend
| extend new_domain = tolower(extract(@'@(.*)', 1, SourceLogin))
Stage 5: where
| where corp_domain != new_domain
Stage 6: extend
| extend AccountCustomEntity = SourceLogin
Stage 7: extend
| extend IPCustomEntity = SrcIpAddr
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 |
|
corp_domain | ne |
|
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 |
|---|---|
corp_domain | extend |
new_domain | extend |
AccountCustomEntity | extend |
IPCustomEntity | extend |