Microsoft Sentinel Analytic Rules
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Base64 encoded Windows process command-lines (Normalized Process Events)

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Idf8b3c49c-4087-499b-920f-0dcfaff0cbca
RulenameBase64 encoded Windows process command-lines (Normalized Process Events)
DescriptionIdentifies instances of a base64 encoded PE file header seen in the process command line parameter.

To use this analytics rule, make sure you have deployed the ASIM normalization parsers
SeverityMedium
TacticsExecution
DefenseEvasion
TechniquesT1059
T1027
T1140
KindScheduled
Query frequency1d
Query period1d
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Detections/ASimProcess/imProcess_base64_encoded_pefile.yaml
Version1.1.1
Arm templatef8b3c49c-4087-499b-920f-0dcfaff0cbca.json
Deploy To Azure
imProcessCreate
  | where CommandLine contains "TVqQAAMAAAAEAAA"
  | where isnotempty(Process)
  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), count() by Dvc, ActorUsername, Process, CommandLine, ActingProcessName, EventVendor, EventProduct
  | extend timestamp = StartTimeUtc, AccountCustomEntity = ActorUsername, HostCustomEntity = Dvc
queryFrequency: 1d
triggerOperator: gt
tactics:
- Execution
- DefenseEvasion
description: |
  'Identifies instances of a base64 encoded PE file header seen in the process command line parameter.
  To use this analytics rule, make sure you have deployed the [ASIM normalization parsers](https://aka.ms/ASimProcessEvent)'  
relevantTechniques:
- T1059
- T1027
- T1140
name: Base64 encoded Windows process command-lines (Normalized Process Events)
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/ASimProcess/imProcess_base64_encoded_pefile.yaml
severity: Medium
triggerThreshold: 0
version: 1.1.1
entityMappings:
- entityType: Account
  fieldMappings:
  - identifier: FullName
    columnName: AccountCustomEntity
- entityType: Host
  fieldMappings:
  - identifier: FullName
    columnName: HostCustomEntity
tags:
- version: 1.0.0
  Id: ca67c83e-7fff-4127-a3e3-1af66d6d4cad
- Schema: ASIMProcessEvent
  SchemaVersion: 0.1.0
id: f8b3c49c-4087-499b-920f-0dcfaff0cbca
requiredDataConnectors: []
kind: Scheduled
query: |
  imProcessCreate
    | where CommandLine contains "TVqQAAMAAAAEAAA"
    | where isnotempty(Process)
    | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), count() by Dvc, ActorUsername, Process, CommandLine, ActingProcessName, EventVendor, EventProduct
    | extend timestamp = StartTimeUtc, AccountCustomEntity = ActorUsername, HostCustomEntity = Dvc  
queryPeriod: 1d
{
  "$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/f8b3c49c-4087-499b-920f-0dcfaff0cbca')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/f8b3c49c-4087-499b-920f-0dcfaff0cbca')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01",
      "properties": {
        "displayName": "Base64 encoded Windows process command-lines (Normalized Process Events)",
        "description": "'Identifies instances of a base64 encoded PE file header seen in the process command line parameter.\nTo use this analytics rule, make sure you have deployed the [ASIM normalization parsers](https://aka.ms/ASimProcessEvent)'\n",
        "severity": "Medium",
        "enabled": true,
        "query": "imProcessCreate\n  | where CommandLine contains \"TVqQAAMAAAAEAAA\"\n  | where isnotempty(Process)\n  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), count() by Dvc, ActorUsername, Process, CommandLine, ActingProcessName, EventVendor, EventProduct\n  | extend timestamp = StartTimeUtc, AccountCustomEntity = ActorUsername, HostCustomEntity = Dvc\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P1D",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Execution",
          "DefenseEvasion"
        ],
        "techniques": [
          "T1059",
          "T1027",
          "T1140"
        ],
        "alertRuleTemplateName": "f8b3c49c-4087-499b-920f-0dcfaff0cbca",
        "customDetails": null,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "AccountCustomEntity"
              }
            ]
          },
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "identifier": "FullName",
                "columnName": "HostCustomEntity"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/ASimProcess/imProcess_base64_encoded_pefile.yaml",
        "tags": [
          {
            "Id": "ca67c83e-7fff-4127-a3e3-1af66d6d4cad",
            "version": "1.0.0"
          },
          {
            "Schema": "ASIMProcessEvent",
            "SchemaVersion": "0.1.0"
          }
        ],
        "templateVersion": "1.1.1"
      }
    }
  ]
}