Cisco SEG - Unexpected link

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Id	9cb4a02d-3708-42ba-b33b-0fdd360ce4b6
Rulename	Cisco SEG - Unexpected link
Description	Detects mails with suspicious links.
Severity	Medium
Tactics	InitialAccess
Techniques	T1566
Required data connectors	CefAma
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/CiscoSEG/Analytic Rules/CiscoSEGUnclassifiedLink.yaml
Version	1.0.3
Arm template	9cb4a02d-3708-42ba-b33b-0fdd360ce4b6.json

KQL

let u_cat = dynamic(['Unclassified']);
CiscoSEGEvent
| where NetworkDirection =~ 'Incoming'
| where tostring(AdditionalFields) has 'ESAURLDetails'
| extend link_cat = extract(@"'Category': '(.*?)'", 1, tostring(AdditionalFields))
| where link_cat in~ (u_cat)
| extend AccountCustomEntity = DstUserName

YAML

description: |
    'Detects mails with suspicious links.'
version: 1.0.3
triggerThreshold: 0
tactics:
- InitialAccess
queryPeriod: 1h
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/CiscoSEG/Analytic Rules/CiscoSEGUnclassifiedLink.yaml
triggerOperator: gt
status: Available
id: 9cb4a02d-3708-42ba-b33b-0fdd360ce4b6
name: Cisco SEG - Unexpected link
queryFrequency: 1h
severity: Medium
kind: Scheduled
entityMappings:
- fieldMappings:
  - columnName: AccountCustomEntity
    identifier: Name
  entityType: Account
relevantTechniques:
- T1566
query: |
  let u_cat = dynamic(['Unclassified']);
  CiscoSEGEvent
  | where NetworkDirection =~ 'Incoming'
  | where tostring(AdditionalFields) has 'ESAURLDetails'
  | extend link_cat = extract(@"'Category': '(.*?)'", 1, tostring(AdditionalFields))
  | where link_cat in~ (u_cat)
  | extend AccountCustomEntity = DstUserName  
requiredDataConnectors:
- dataTypes:
  - CommonSecurityLog
  connectorId: CefAma

ARM