Detection rules › Kusto
Box - Forbidden file type downloaded
'Detects when new user downloads forbidden file types.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1189 Drive-by Compromise |
Rule body kusto
id: 8889e69c-2161-412a-94a6-76c1b2d9daa7
name: Box - Forbidden file type downloaded
description: |
'Detects when new user downloads forbidden file types.'
severity: Medium
status: Available
requiredDataConnectors:
- connectorId: BoxDataConnector
dataTypes:
- BoxEvents_CL
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
- InitialAccess
relevantTechniques:
- T1189
query: |
let forbidden_files = dynamic(['ps1', 'bat', 'scr', 'sh']);
BoxEvents
| where EventType =~ 'DOWNLOAD'
| extend file_type = extract(@'\.(\w+)$', 1, SourceItemName)
| where file_type in (forbidden_files)
| extend AccountCustomEntity = SrcUserName
| extend IPCustomEntity = SrcIpAddr
entityMappings:
- entityType: Account
fieldMappings:
- identifier: FullName
columnName: AccountCustomEntity
- entityType: IP
fieldMappings:
- identifier: Address
columnName: IPCustomEntity
version: 1.0.0
kind: Scheduled
Stages and Predicates
Parameters
let forbidden_files = dynamic(['ps1', 'bat', 'scr', 'sh']);
Stage 1: source
BoxEvents
Stage 2: where
| where EventType =~ 'DOWNLOAD'
Stage 3: extend
| extend file_type = extract(@'\.(\w+)$', 1, SourceItemName)
Stage 4: where
| where file_type in (forbidden_files)
Stage 5: extend
| extend AccountCustomEntity = SrcUserName
Stage 6: 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.
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 |
|---|---|
file_type | extend |
AccountCustomEntity | extend |
IPCustomEntity | extend |