Process executed from binary hidden in Base64 encoded file

let ProcessCreationEvents=() {
let processEvents=(union isfuzzy=true
(SecurityEvent
| where EventID==4688
| where isnotempty(CommandLine)
| project TimeGenerated, Computer, Account = SubjectUserName, AccountDomain = SubjectDomainName, FileName = Process, CommandLine, ParentProcessName
),
(WindowsEvent
| where EventID==4688
| where EventData has_any (".decode('base64')", "base64 --decode", ".decode64(" )
| extend CommandLine = tostring(EventData.CommandLine)
| where isnotempty(CommandLine)
| extend SubjectUserName = tostring(EventData.SubjectUserName)
| extend SubjectDomainName = tostring(EventData.SubjectDomainName)
| extend NewProcessName = tostring(EventData.NewProcessName)
| extend FileName=tostring(split(NewProcessName, '\\')[-1])
| extend ParentProcessName = tostring(EventData.ParentProcessName)
| project TimeGenerated, Computer, Account = SubjectUserName, AccountDomain = SubjectDomainName, CommandLine, ParentProcessName
));
processEvents;
};
ProcessCreationEvents 
| where CommandLine contains ".decode('base64')"
        or CommandLine contains "base64 --decode"
        or CommandLine contains ".decode64(" 
| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), CountToday = count() by Computer, Account, AccountDomain, FileName, CommandLine, ParentProcessName 
| extend timestamp = StartTimeUtc, AccountCustomEntity = Account, HostCustomEntity = Computer

version: 1.1.1
status: Available
queryFrequency: 1d
requiredDataConnectors:
- connectorId: SecurityEvents
  dataTypes:
  - SecurityEvent
- connectorId: WindowsSecurityEvents
  dataTypes:
  - SecurityEvent
- connectorId: WindowsSecurityEvents
  dataTypes:
  - SecurityEvents
- connectorId: WindowsForwardedEvents
  dataTypes:
  - WindowsEvent
entityMappings:
- fieldMappings:
  - columnName: AccountCustomEntity
    identifier: FullName
  entityType: Account
- fieldMappings:
  - columnName: HostCustomEntity
    identifier: FullName
  entityType: Host
kind: Scheduled
queryPeriod: 1d
severity: Medium
query: |
  let ProcessCreationEvents=() {
  let processEvents=(union isfuzzy=true
  (SecurityEvent
  | where EventID==4688
  | where isnotempty(CommandLine)
  | project TimeGenerated, Computer, Account = SubjectUserName, AccountDomain = SubjectDomainName, FileName = Process, CommandLine, ParentProcessName
  ),
  (WindowsEvent
  | where EventID==4688
  | where EventData has_any (".decode('base64')", "base64 --decode", ".decode64(" )
  | extend CommandLine = tostring(EventData.CommandLine)
  | where isnotempty(CommandLine)
  | extend SubjectUserName = tostring(EventData.SubjectUserName)
  | extend SubjectDomainName = tostring(EventData.SubjectDomainName)
  | extend NewProcessName = tostring(EventData.NewProcessName)
  | extend FileName=tostring(split(NewProcessName, '\\')[-1])
  | extend ParentProcessName = tostring(EventData.ParentProcessName)
  | project TimeGenerated, Computer, Account = SubjectUserName, AccountDomain = SubjectDomainName, CommandLine, ParentProcessName
  ));
  processEvents;
  };
  ProcessCreationEvents 
  | where CommandLine contains ".decode('base64')"
          or CommandLine contains "base64 --decode"
          or CommandLine contains ".decode64(" 
  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), CountToday = count() by Computer, Account, AccountDomain, FileName, CommandLine, ParentProcessName 
  | extend timestamp = StartTimeUtc, AccountCustomEntity = Account, HostCustomEntity = Computer  
triggerOperator: gt
id: d6190dde-8fd2-456a-ac5b-0a32400b0464
description: |
  'Encoding malicious software is a technique used to obfuscate files from detection. 
  The first CommandLine component is looking for Python decoding base64. 
  The second CommandLine component is looking for Bash/sh command line base64 decoding.
  The third one is looking for Ruby decoding base64.'  
triggerThreshold: 0
name: Process executed from binary hidden in Base64 encoded file
relevantTechniques:
- T1059
- T1027
- T1140
tactics:
- Execution
- DefenseEvasion
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Endpoint Threat Protection Essentials/Analytic Rules/execute_base64_decodedpayload.yaml

{
  "$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/d6190dde-8fd2-456a-ac5b-0a32400b0464')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/d6190dde-8fd2-456a-ac5b-0a32400b0464')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01",
      "properties": {
        "displayName": "Process executed from binary hidden in Base64 encoded file",
        "description": "'Encoding malicious software is a technique used to obfuscate files from detection. \nThe first CommandLine component is looking for Python decoding base64. \nThe second CommandLine component is looking for Bash/sh command line base64 decoding.\nThe third one is looking for Ruby decoding base64.'\n",
        "severity": "Medium",
        "enabled": true,
        "query": "let ProcessCreationEvents=() {\nlet processEvents=(union isfuzzy=true\n(SecurityEvent\n| where EventID==4688\n| where isnotempty(CommandLine)\n| project TimeGenerated, Computer, Account = SubjectUserName, AccountDomain = SubjectDomainName, FileName = Process, CommandLine, ParentProcessName\n),\n(WindowsEvent\n| where EventID==4688\n| where EventData has_any (\".decode('base64')\", \"base64 --decode\", \".decode64(\" )\n| extend CommandLine = tostring(EventData.CommandLine)\n| where isnotempty(CommandLine)\n| extend SubjectUserName = tostring(EventData.SubjectUserName)\n| extend SubjectDomainName = tostring(EventData.SubjectDomainName)\n| extend NewProcessName = tostring(EventData.NewProcessName)\n| extend FileName=tostring(split(NewProcessName, '\\\\')[-1])\n| extend ParentProcessName = tostring(EventData.ParentProcessName)\n| project TimeGenerated, Computer, Account = SubjectUserName, AccountDomain = SubjectDomainName, CommandLine, ParentProcessName\n));\nprocessEvents;\n};\nProcessCreationEvents \n| where CommandLine contains \".decode('base64')\"\n        or CommandLine contains \"base64 --decode\"\n        or CommandLine contains \".decode64(\" \n| summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), CountToday = count() by Computer, Account, AccountDomain, FileName, CommandLine, ParentProcessName \n| extend timestamp = StartTimeUtc, AccountCustomEntity = Account, HostCustomEntity = Computer\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P1D",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Execution",
          "DefenseEvasion"
        ],
        "techniques": [
          "T1059",
          "T1027",
          "T1140"
        ],
        "alertRuleTemplateName": "d6190dde-8fd2-456a-ac5b-0a32400b0464",
        "customDetails": null,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "AccountCustomEntity"
              }
            ]
          },
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "HostCustomEntity"
              }
            ]
          }
        ],
        "status": "Available",
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Endpoint Threat Protection Essentials/Analytic Rules/execute_base64_decodedpayload.yaml",
        "templateVersion": "1.1.1"
      }
    }
  ]
}