Potential Build Process Compromise - MDE

// How far back to look for events from
let timeframe = 1d;
// How close together build events and file modifications should occur to alert (make this smaller to reduce FPs)
let time_window = 5m;
// Edit this to include build processes used
let build_processes = dynamic(["MSBuild.exe", "dotnet.exe", "VBCSCompiler.exe"]);
// Include any processes that you want to allow to edit files during/around the build process
let allow_list = dynamic([]);
DeviceProcessEvents
| where TimeGenerated > ago(timeframe)
// Look for build process starts
| where FileName has_any (build_processes)
| summarize by BuildParentProcess=InitiatingProcessFileName, BuildProcess=FileName, BuildAccount = AccountName, DeviceName, BuildCommand=ProcessCommandLine, timekey= bin(TimeGenerated, time_window), BuildProcessTime=TimeGenerated
| join kind=inner(
DeviceFileEvents
| where TimeGenerated > ago(timeframe)
| where InitiatingProcessFileName !in (allow_list)
| where ActionType == "FileCreated"  or ActionType == "FileModified"
// Look for code files, edit this to include file extensions used in build.
| where FileName endswith ".cs" or FileName endswith ".cpp"
| summarize by FileEditParentProcess=InitiatingProcessParentFileName, FileEditAccount = InitiatingProcessAccountName, DeviceName, FileEdited=FileName, FileEditProcess=InitiatingProcessFileName, timekey= bin(TimeGenerated, time_window), FileEditTime=TimeGenerated)
// join where build processes and file modifications seen at same time on same host
on timekey, DeviceName
// Limit to only where the file edit happens after the build process starts
| where BuildProcessTime <= FileEditTime
| summarize make_set(FileEdited), make_set(FileEditProcess), make_set(FileEditAccount) by timekey, DeviceName, BuildParentProcess, BuildProcess
| extend HostName = iff(DeviceName has '.', substring(DeviceName,0,indexof(DeviceName,'.')),DeviceName)
| extend DnsDomain = iff(DeviceName has '.', substring(DeviceName,indexof(DeviceName,'.')+1),"")

severity: Medium
queryFrequency: 1d
relevantTechniques:
- T1554
tactics:
- Persistence
kind: Scheduled
query: |
  // How far back to look for events from
  let timeframe = 1d;
  // How close together build events and file modifications should occur to alert (make this smaller to reduce FPs)
  let time_window = 5m;
  // Edit this to include build processes used
  let build_processes = dynamic(["MSBuild.exe", "dotnet.exe", "VBCSCompiler.exe"]);
  // Include any processes that you want to allow to edit files during/around the build process
  let allow_list = dynamic([]);
  DeviceProcessEvents
  | where TimeGenerated > ago(timeframe)
  // Look for build process starts
  | where FileName has_any (build_processes)
  | summarize by BuildParentProcess=InitiatingProcessFileName, BuildProcess=FileName, BuildAccount = AccountName, DeviceName, BuildCommand=ProcessCommandLine, timekey= bin(TimeGenerated, time_window), BuildProcessTime=TimeGenerated
  | join kind=inner(
  DeviceFileEvents
  | where TimeGenerated > ago(timeframe)
  | where InitiatingProcessFileName !in (allow_list)
  | where ActionType == "FileCreated"  or ActionType == "FileModified"
  // Look for code files, edit this to include file extensions used in build.
  | where FileName endswith ".cs" or FileName endswith ".cpp"
  | summarize by FileEditParentProcess=InitiatingProcessParentFileName, FileEditAccount = InitiatingProcessAccountName, DeviceName, FileEdited=FileName, FileEditProcess=InitiatingProcessFileName, timekey= bin(TimeGenerated, time_window), FileEditTime=TimeGenerated)
  // join where build processes and file modifications seen at same time on same host
  on timekey, DeviceName
  // Limit to only where the file edit happens after the build process starts
  | where BuildProcessTime <= FileEditTime
  | summarize make_set(FileEdited), make_set(FileEditProcess), make_set(FileEditAccount) by timekey, DeviceName, BuildParentProcess, BuildProcess
  | extend HostName = iff(DeviceName has '.', substring(DeviceName,0,indexof(DeviceName,'.')),DeviceName)
  | extend DnsDomain = iff(DeviceName has '.', substring(DeviceName,indexof(DeviceName,'.')+1),"")  
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft 365 Defender/Analytic Rules/PotentialBuildProcessCompromiseMDE.yaml
queryPeriod: 1d
status: Available
version: 1.0.1
tags:
- Solorigate
- NOBELIUM
name: Potential Build Process Compromise - MDE
requiredDataConnectors:
- dataTypes:
  - DeviceProcessEvents
  - DeviceFileEvents
  connectorId: MicrosoftThreatProtection
triggerOperator: gt
entityMappings:
- entityType: Host
  fieldMappings:
  - identifier: HostName
    columnName: HostName
  - identifier: DnsDomain
    columnName: DnsDomain
id: 1bf6e165-5e32-420e-ab4f-0da8558a8be2
description: |
  'The query looks for source code files being modified immediately after a build process is started. The purpose of this is to look for malicious code injection during the build process. This query uses Microsoft Defender for Endpoint telemetry.
  More details: https://techcommunity.microsoft.com/t5/azure-sentinel/monitoring-the-software-supply-chain-with-azure-sentinel/ba-p/2176463'  
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/1bf6e165-5e32-420e-ab4f-0da8558a8be2')]",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/1bf6e165-5e32-420e-ab4f-0da8558a8be2')]",
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules",
      "kind": "Scheduled",
      "apiVersion": "2022-11-01-preview",
      "properties": {
        "displayName": "Potential Build Process Compromise - MDE",
        "description": "'The query looks for source code files being modified immediately after a build process is started. The purpose of this is to look for malicious code injection during the build process. This query uses Microsoft Defender for Endpoint telemetry.\nMore details: https://techcommunity.microsoft.com/t5/azure-sentinel/monitoring-the-software-supply-chain-with-azure-sentinel/ba-p/2176463'\n",
        "severity": "Medium",
        "enabled": true,
        "query": "// How far back to look for events from\nlet timeframe = 1d;\n// How close together build events and file modifications should occur to alert (make this smaller to reduce FPs)\nlet time_window = 5m;\n// Edit this to include build processes used\nlet build_processes = dynamic([\"MSBuild.exe\", \"dotnet.exe\", \"VBCSCompiler.exe\"]);\n// Include any processes that you want to allow to edit files during/around the build process\nlet allow_list = dynamic([]);\nDeviceProcessEvents\n| where TimeGenerated > ago(timeframe)\n// Look for build process starts\n| where FileName has_any (build_processes)\n| summarize by BuildParentProcess=InitiatingProcessFileName, BuildProcess=FileName, BuildAccount = AccountName, DeviceName, BuildCommand=ProcessCommandLine, timekey= bin(TimeGenerated, time_window), BuildProcessTime=TimeGenerated\n| join kind=inner(\nDeviceFileEvents\n| where TimeGenerated > ago(timeframe)\n| where InitiatingProcessFileName !in (allow_list)\n| where ActionType == \"FileCreated\"  or ActionType == \"FileModified\"\n// Look for code files, edit this to include file extensions used in build.\n| where FileName endswith \".cs\" or FileName endswith \".cpp\"\n| summarize by FileEditParentProcess=InitiatingProcessParentFileName, FileEditAccount = InitiatingProcessAccountName, DeviceName, FileEdited=FileName, FileEditProcess=InitiatingProcessFileName, timekey= bin(TimeGenerated, time_window), FileEditTime=TimeGenerated)\n// join where build processes and file modifications seen at same time on same host\non timekey, DeviceName\n// Limit to only where the file edit happens after the build process starts\n| where BuildProcessTime <= FileEditTime\n| summarize make_set(FileEdited), make_set(FileEditProcess), make_set(FileEditAccount) by timekey, DeviceName, BuildParentProcess, BuildProcess\n| extend HostName = iff(DeviceName has '.', substring(DeviceName,0,indexof(DeviceName,'.')),DeviceName)\n| extend DnsDomain = iff(DeviceName has '.', substring(DeviceName,indexof(DeviceName,'.')+1),\"\")\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P1D",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0,
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Persistence"
        ],
        "techniques": [
          "T1554"
        ],
        "alertRuleTemplateName": "1bf6e165-5e32-420e-ab4f-0da8558a8be2",
        "customDetails": null,
        "entityMappings": [
          {
            "fieldMappings": [
              {
                "columnName": "HostName",
                "identifier": "HostName"
              },
              {
                "columnName": "DnsDomain",
                "identifier": "DnsDomain"
              }
            ],
            "entityType": "Host"
          }
        ],
        "tags": [
          "Solorigate",
          "NOBELIUM"
        ],
        "status": "Available",
        "templateVersion": "1.0.1",
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft 365 Defender/Analytic Rules/PotentialBuildProcessCompromiseMDE.yaml"
      }
    }
  ]
}