detection.wiki

Detection rules › Kusto

PaloAlto - File type changed

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

'Detects when file type changed.'

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1133 External Remote Services, T1190 Exploit Public-Facing Application

Rule body kusto

id: 9150ad68-51c8-11ec-bf63-0242ac130002
name: PaloAlto - File type changed
description: |
  'Detects when file type changed.'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: CefAma
    dataTypes:
      - CommonSecurityLog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1190
  - T1133
query: |
  PaloAltoCDLEvent
  | where EventResourceId =~ 'THREAT'
  | where EventResult =~ 'file'
  | where FileType != OldFileType
  | extend FileCustomEntity = SrcFileName, AccountCustomEntity = DstUsername
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: AccountCustomEntity
  - entityType: File
    fieldMappings:
      - identifier: Name
        columnName: FileCustomEntity
version: 1.0.3
kind: Scheduled

Stages and Predicates

Stage 1: source

PaloAltoCDLEvent

Stage 2: where

| where EventResourceId =~ 'THREAT'

Stage 3: where

| where EventResult =~ 'file'

Stage 4: where

| where FileType != OldFileType

Stage 5: extend

| extend FileCustomEntity = SrcFileName, AccountCustomEntity = DstUsername

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.

FieldKindValues
EventResourceIdeq
  • THREAT
EventResulteq
  • file
FileTypene
  • OldFileType 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.

FieldSource
AccountCustomEntityextend
FileCustomEntityextend