MosaicLoader

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Id	506f4d6b-3864-4bb1-8f75-a13fb066f97a
Rulename	MosaicLoader
Description	This query looks Malware Hides Itself Among Windows Defender Exclusions to Evade Detection.
Severity	High
Tactics	DefenseEvasion
Techniques	T1562
Required data connectors	MicrosoftThreatProtection
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/Microsoft Defender XDR/Analytic Rules/Exploits/MosaicLoader.yaml
Version	1.0.0
Arm template	506f4d6b-3864-4bb1-8f75-a13fb066f97a.json

KQL

DeviceRegistryEvents 
| where ((ActionType == "RegistryValueSet") and (RegistryKey startswith @"HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows Defender\\Exclusions\\Paths" 
or RegistryKey startswith @"HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender\Exclusions\Extensions"
or RegistryKey startswith @"HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender\Exclusions\Processes"))
| extend HostName = iff(DeviceName has '.', substring(DeviceName, 0, indexof(DeviceName, '.')), DeviceName)
| extend DnsDomain = iff(DeviceName has '.', substring(DeviceName, indexof(DeviceName, '.') + 1), "")

YAML

queryPeriod: 1h
name: MosaicLoader
description: |
    This query looks Malware Hides Itself Among Windows Defender Exclusions to Evade Detection.
status: Available
requiredDataConnectors:
- dataTypes:
  - DeviceRegistryEvents
  connectorId: MicrosoftThreatProtection
kind: Scheduled
id: 506f4d6b-3864-4bb1-8f75-a13fb066f97a
version: 1.0.0
triggerOperator: gt
triggerThreshold: 0
query: |
  DeviceRegistryEvents 
  | where ((ActionType == "RegistryValueSet") and (RegistryKey startswith @"HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows Defender\\Exclusions\\Paths" 
  or RegistryKey startswith @"HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender\Exclusions\Extensions"
  or RegistryKey startswith @"HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender\Exclusions\Processes"))
  | 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 Defender XDR/Analytic Rules/Exploits/MosaicLoader.yaml
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: DeviceName
  - identifier: HostName
    columnName: HostName
  - identifier: DnsDomain
    columnName: DnsDomain
  entityType: Host
- fieldMappings:
  - identifier: Name
    columnName: RegistryValueName
  - identifier: Value
    columnName: RegistryValueData
  entityType: RegistryValue
tactics:
- DefenseEvasion
relevantTechniques:
- T1562
queryFrequency: 1h
severity: High
tags:
- MosaicLoader
- Windows Defender Exclusions

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2024-01-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/506f4d6b-3864-4bb1-8f75-a13fb066f97a')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/506f4d6b-3864-4bb1-8f75-a13fb066f97a')]",
      "properties": {
        "alertRuleTemplateName": "506f4d6b-3864-4bb1-8f75-a13fb066f97a",
        "customDetails": null,
        "description": "This query looks Malware Hides Itself Among Windows Defender Exclusions to Evade Detection.\n",
        "displayName": "MosaicLoader",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "DeviceName",
                "identifier": "FullName"
              },
              {
                "columnName": "HostName",
                "identifier": "HostName"
              },
              {
                "columnName": "DnsDomain",
                "identifier": "DnsDomain"
              }
            ]
          },
          {
            "entityType": "RegistryValue",
            "fieldMappings": [
              {
                "columnName": "RegistryValueName",
                "identifier": "Name"
              },
              {
                "columnName": "RegistryValueData",
                "identifier": "Value"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Defender XDR/Analytic Rules/Exploits/MosaicLoader.yaml",
        "query": "DeviceRegistryEvents \n| where ((ActionType == \"RegistryValueSet\") and (RegistryKey startswith @\"HKEY_LOCAL_MACHINE\\\\SOFTWARE\\\\Microsoft\\\\Windows Defender\\\\Exclusions\\\\Paths\" \nor RegistryKey startswith @\"HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows Defender\\Exclusions\\Extensions\"\nor RegistryKey startswith @\"HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows Defender\\Exclusions\\Processes\"))\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": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "High",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "DefenseEvasion"
        ],
        "tags": [
          "MosaicLoader",
          "Windows Defender Exclusions"
        ],
        "techniques": [
          "T1562"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}