Corelight
| where EventType =~ 'smtp'
| where Subject hasprefix @'\=?utf-16'
| summarize recipients = dcount(To)
| extend k = 1
| join (Corelight
| where Subject hasprefix @'\=?utf-16'
| summarize by To
| extend k = 1) on k
| where recipients > 1
| extend MailCustomEntity = To
severity: Low
queryFrequency: 1h
relevantTechniques:
- T1566
tactics:
- InitialAccess
kind: Scheduled
query: |
Corelight
| where EventType =~ 'smtp'
| where Subject hasprefix @'\=?utf-16'
| summarize recipients = dcount(To)
| extend k = 1
| join (Corelight
| where Subject hasprefix @'\=?utf-16'
| summarize by To
| extend k = 1) on k
| where recipients > 1
| extend MailCustomEntity = To
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Corelight/Analytic Rules/CorelightSMTPEmailSubjectNonAsciiCharacters.yaml
queryPeriod: 1h
status: Available
version: 1.0.0
name: Corelight - SMTP Email containing NON Ascii Characters within the Subject
requiredDataConnectors:
- dataTypes:
- Corelight
connectorId: Corelight
triggerOperator: gt
entityMappings:
- entityType: MailMessage
fieldMappings:
- identifier: Recipient
columnName: MailCustomEntity
id: 50c61708-9824-46f3-87cf-22490796fae2
description: |
'Detects where an emails contain non ascii characters within the Subject.'
triggerThreshold: 0
{
"$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"workspace": {
"type": "String"
}
},
"resources": [
{
"id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/50c61708-9824-46f3-87cf-22490796fae2')]",
"name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/50c61708-9824-46f3-87cf-22490796fae2')]",
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
"kind": "Scheduled",
"apiVersion": "2022-11-01-preview",
"properties": {
"displayName": "Corelight - SMTP Email containing NON Ascii Characters within the Subject",
"description": "'Detects where an emails contain non ascii characters within the Subject.'\n",
"severity": "Low",
"enabled": true,
"query": "Corelight\n| where EventType =~ 'smtp'\n| where Subject hasprefix @'\\=?utf-16'\n| summarize recipients = dcount(To)\n| extend k = 1\n| join (Corelight\n | where Subject hasprefix @'\\=?utf-16'\n | summarize by To\n | extend k = 1) on k\n| where recipients > 1\n| extend MailCustomEntity = To\n",
"queryFrequency": "PT1H",
"queryPeriod": "PT1H",
"triggerOperator": "GreaterThan",
"triggerThreshold": 0,
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"InitialAccess"
],
"techniques": [
"T1566"
],
"alertRuleTemplateName": "50c61708-9824-46f3-87cf-22490796fae2",
"customDetails": null,
"entityMappings": [
{
"fieldMappings": [
{
"columnName": "MailCustomEntity",
"identifier": "Recipient"
}
],
"entityType": "MailMessage"
}
],
"templateVersion": "1.0.0",
"status": "Available",
"OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Corelight/Analytic Rules/CorelightSMTPEmailSubjectNonAsciiCharacters.yaml"
}
}
]
}