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Detection rules › Kusto

Cisco WSA - Unexpected URL

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

'Detects unexpected URL.'

MITRE ATT&CK coverage

TacticTechniques
Command & ControlT1102 Web Service

Rule body kusto

id: 010644fd-2830-4451-9e0e-606cc192f2e7
name: Cisco WSA - Unexpected URL
description: |
  'Detects unexpected URL.'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: SyslogAma
    datatypes:
      - Syslog
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
relevantTechniques:
  - T1102
query: |
  let threshold = 5;
  CiscoWSAEvent
  | where UrlOriginal matches regex @'\Ahttp(s)?[:][/][/]\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}'
  | extend URLCustomEntity = UrlOriginal, AccountCustomEntity = SrcUserName
entityMappings:
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: URLCustomEntity
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: AccountCustomEntity
version: 1.0.2
kind: Scheduled

Stages and Predicates

Parameters

let threshold = 5;

Stage 1: source

CiscoWSAEvent

Stage 2: where

| where UrlOriginal matches regex @'\Ahttp(s)?[:][/][/]\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}'

Stage 3: extend

| extend URLCustomEntity = UrlOriginal, AccountCustomEntity = SrcUserName

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
UrlOriginalregex_match
  • \Ahttp(s)?[:][/][/]\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}

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
URLCustomEntityextend