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

ARM

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2023-02-01-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",
        "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"
    }
  ]
}