Cloudflare - XSS probing pattern in request

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Id	4d9d00b9-31a6-49e4-88c1-9e68277053ac
Rulename	Cloudflare - XSS probing pattern in request
Description	Detects XSS probing patterns.
Severity	Medium
Tactics	InitialAccess
Techniques	T1190 T1133
Required data connectors	CloudflareDataConnector
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Cloudflare/Analytic Rules/CloudflareXSSProbingPattern.yaml
Version	1.0.1
Arm template	4d9d00b9-31a6-49e4-88c1-9e68277053ac.json

KQL

let s_threshold = 3;
Cloudflare
| where HttpRequestMethod in~ ('POST', 'PUT')
| extend susp_ch = countof(ClientRequestURI, '%00')
| where ClientRequestURI matches regex @'(alert\()|(alert\%28)|(String\.fromCharCode\()|(expression\(alert)' or susp_ch > s_threshold 
| extend CompleteUrl = strcat(HttpRequestHeaderHost,ClientRequestPath)

YAML

triggerThreshold: 0
entityMappings:
- entityType: IP
  fieldMappings:
  - identifier: Address
    columnName: SrcIpAddr
- entityType: URL
  fieldMappings:
  - identifier: Url
    columnName: CompleteUrl
requiredDataConnectors:
- dataTypes:
  - Cloudflare
  connectorId: CloudflareDataConnector
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Cloudflare/Analytic Rules/CloudflareXSSProbingPattern.yaml
name: Cloudflare - XSS probing pattern in request
relevantTechniques:
- T1190
- T1133
status: Available
version: 1.0.1
queryPeriod: 1h
kind: Scheduled
id: 4d9d00b9-31a6-49e4-88c1-9e68277053ac
query: |
  let s_threshold = 3;
  Cloudflare
  | where HttpRequestMethod in~ ('POST', 'PUT')
  | extend susp_ch = countof(ClientRequestURI, '%00')
  | where ClientRequestURI matches regex @'(alert\()|(alert\%28)|(String\.fromCharCode\()|(expression\(alert)' or susp_ch > s_threshold 
  | extend CompleteUrl = strcat(HttpRequestHeaderHost,ClientRequestPath)  
description: |
    'Detects XSS probing patterns.'
queryFrequency: 1h
severity: Medium
triggerOperator: gt
tactics:
- InitialAccess

ARM