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

description: |
    This query looks Malware Hides Itself Among Windows Defender Exclusions to Evade Detection.
triggerOperator: gt
requiredDataConnectors:
- dataTypes:
  - DeviceRegistryEvents
  connectorId: MicrosoftThreatProtection
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), "")  
name: MosaicLoader
entityMappings:
- entityType: Host
  fieldMappings:
  - identifier: FullName
    columnName: DeviceName
  - identifier: HostName
    columnName: HostName
  - identifier: DnsDomain
    columnName: DnsDomain
- entityType: RegistryValue
  fieldMappings:
  - identifier: Name
    columnName: RegistryValueName
  - identifier: Value
    columnName: RegistryValueData
kind: Scheduled
severity: High
relevantTechniques:
- T1562
tactics:
- DefenseEvasion
queryFrequency: 1h
tags:
- MosaicLoader
- Windows Defender Exclusions
version: 1.0.0
queryPeriod: 1h
triggerThreshold: 0
status: Available
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Microsoft Defender XDR/Analytic Rules/Exploits/MosaicLoader.yaml
id: 506f4d6b-3864-4bb1-8f75-a13fb066f97a

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"
    }
  ]
}