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Detection rules › Kusto

Imperva - Critical severity event not blocked

Status
available
Severity
high
Time window
10m
Source
github.com/Azure/Azure-Sentinel

'Detects when critical severity event was not blocked.'

MITRE ATT&CK coverage

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

Rule body kusto

id: 4d365217-f96a-437c-9c57-53594fa261c3
name: Imperva - Critical severity event not blocked
description: |
  'Detects when critical severity event was not blocked.'
severity: High
status: Available
requiredDataConnectors:
  - connectorId: ImpervaWAFCloudAPI
    dataTypes:
      - ImpervaWAFCloud
queryFrequency: 10m
queryPeriod: 10m
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1190
  - T1133
query: |
  ImpervaWAFCloud
  | where EventSeverity =~ 'CRITICAL'
  | where DvcAction !startswith 'REQ_BLOCKED' or DvcAction !startswith 'REQ_BAD_'
  | extend IPCustomEntity = SrcIpAddr
entityMappings:
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IPCustomEntity
version: 1.0.1
kind: Scheduled

Stages and Predicates

Stage 1: source

ImpervaWAFCloud

Stage 2: where

| where EventSeverity =~ 'CRITICAL'

Stage 3: where

| where DvcAction !startswith 'REQ_BLOCKED' or DvcAction !startswith 'REQ_BAD_'

Stage 4: 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.

FieldKindValues
EventSeverityeq
  • CRITICAL

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
IPCustomEntityextend