Microsoft Sentinel Analytic Rules
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Scheduled Task Hide

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Id6dd2629c-534b-4275-8201-d7968b4fa77e
RulenameScheduled Task Hide
DescriptionThis query detects attempts by malware to hide the scheduled task by deleting the SD (Security Descriptor) value. Removal of SD value results in the scheduled task disappearing from schtasks /query and Task Scheduler.

The query requires auditing to be turned on for HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree registry hive as well as audit policy for registry auditing to be turned on.

Reference: https://www.microsoft.com/security/blog/2022/04/12/tarrask-malware-uses-scheduled-tasks-for-defense-evasion/

Reference: https://4sysops.com/archives/audit-changes-in-the-windows-registry/
SeverityHigh
TacticsDefenseEvasion
TechniquesT1562
Required data connectorsSecurityEvents
WindowsSecurityEvents
KindScheduled
Query frequency1d
Query period1d
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Windows Security Events/Analytic Rules/ScheduleTaskHide.yaml
Version1.0.1
Arm template6dd2629c-534b-4275-8201-d7968b4fa77e.json
Deploy To Azure
SecurityEvent
| where EventID == 4657
| extend EventData = parse_xml(EventData).EventData.Data
| mv-expand bagexpansion=array EventData
| evaluate bag_unpack(EventData)
| extend Key = tostring(column_ifexists('@Name', "")), Value = column_ifexists('#text', "")
| evaluate pivot(Key, any(Value), TimeGenerated, TargetAccount, Computer, EventSourceName, Channel, Task, Level, EventID, Activity, TargetLogonId, SourceComputerId, EventOriginId, Type, _ResourceId, TenantId, SourceSystem, ManagementGroupName, IpAddress, Account)
| extend ObjectName = column_ifexists('ObjectName', ""), OperationType = column_ifexists('OperationType', ""), ObjectValueName = column_ifexists('ObjectValueName', "")
| where ObjectName has 'Schedule\\TaskCache\\Tree' and ObjectValueName == "SD" and OperationType == "%%1906"  // %%1906 - Registry value deleted
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| extend AccountName = tostring(split(TargetAccount, @'\')[1]), AccountNTDomain = tostring(split(TargetAccount, @'\')[0])
| extend timestamp = TimeGenerated
requiredDataConnectors:
- dataTypes:
  - SecurityEvent
  connectorId: SecurityEvents
- dataTypes:
  - SecurityEvent
  connectorId: WindowsSecurityEvents
triggerThreshold: 0
relevantTechniques:
- T1562
queryPeriod: 1d
version: 1.0.1
tags:
- Tarrask
id: 6dd2629c-534b-4275-8201-d7968b4fa77e
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Windows Security Events/Analytic Rules/ScheduleTaskHide.yaml
query: |
  SecurityEvent
  | where EventID == 4657
  | extend EventData = parse_xml(EventData).EventData.Data
  | mv-expand bagexpansion=array EventData
  | evaluate bag_unpack(EventData)
  | extend Key = tostring(column_ifexists('@Name', "")), Value = column_ifexists('#text', "")
  | evaluate pivot(Key, any(Value), TimeGenerated, TargetAccount, Computer, EventSourceName, Channel, Task, Level, EventID, Activity, TargetLogonId, SourceComputerId, EventOriginId, Type, _ResourceId, TenantId, SourceSystem, ManagementGroupName, IpAddress, Account)
  | extend ObjectName = column_ifexists('ObjectName', ""), OperationType = column_ifexists('OperationType', ""), ObjectValueName = column_ifexists('ObjectValueName', "")
  | where ObjectName has 'Schedule\\TaskCache\\Tree' and ObjectValueName == "SD" and OperationType == "%%1906"  // %%1906 - Registry value deleted
  | extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
  | extend AccountName = tostring(split(TargetAccount, @'\')[1]), AccountNTDomain = tostring(split(TargetAccount, @'\')[0])
  | extend timestamp = TimeGenerated  
status: Available
entityMappings:
- fieldMappings:
  - identifier: FullName
    columnName: TargetAccount
  - identifier: Name
    columnName: AccountName
  - identifier: NTDomain
    columnName: AccountNTDomain
  entityType: Account
- fieldMappings:
  - identifier: FullName
    columnName: Computer
  - identifier: HostName
    columnName: HostName
  - identifier: DnsDomain
    columnName: HostNameDomain
  entityType: Host
tactics:
- DefenseEvasion
severity: High
name: Scheduled Task Hide
queryFrequency: 1d
triggerOperator: gt
kind: Scheduled
description: |
  'This query detects attempts by malware to hide the scheduled task by deleting the SD (Security Descriptor) value. Removal of SD value results in the scheduled task disappearing from schtasks /query and Task Scheduler.
   The query requires auditing to be turned on for HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree registry hive as well as audit policy for registry auditing to be turned on.
   Reference: https://www.microsoft.com/security/blog/2022/04/12/tarrask-malware-uses-scheduled-tasks-for-defense-evasion/
   Reference: https://4sysops.com/archives/audit-changes-in-the-windows-registry/'  
{
  "$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/6dd2629c-534b-4275-8201-d7968b4fa77e')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/6dd2629c-534b-4275-8201-d7968b4fa77e')]",
      "properties": {
        "alertRuleTemplateName": "6dd2629c-534b-4275-8201-d7968b4fa77e",
        "customDetails": null,
        "description": "'This query detects attempts by malware to hide the scheduled task by deleting the SD (Security Descriptor) value. Removal of SD value results in the scheduled task disappearing from schtasks /query and Task Scheduler.\n The query requires auditing to be turned on for HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Schedule\\TaskCache\\Tree registry hive as well as audit policy for registry auditing to be turned on.\n Reference: https://www.microsoft.com/security/blog/2022/04/12/tarrask-malware-uses-scheduled-tasks-for-defense-evasion/\n Reference: https://4sysops.com/archives/audit-changes-in-the-windows-registry/'\n",
        "displayName": "Scheduled Task Hide",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "TargetAccount",
                "identifier": "FullName"
              },
              {
                "columnName": "AccountName",
                "identifier": "Name"
              },
              {
                "columnName": "AccountNTDomain",
                "identifier": "NTDomain"
              }
            ]
          },
          {
            "entityType": "Host",
            "fieldMappings": [
              {
                "columnName": "Computer",
                "identifier": "FullName"
              },
              {
                "columnName": "HostName",
                "identifier": "HostName"
              },
              {
                "columnName": "HostNameDomain",
                "identifier": "DnsDomain"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Windows Security Events/Analytic Rules/ScheduleTaskHide.yaml",
        "query": "SecurityEvent\n| where EventID == 4657\n| extend EventData = parse_xml(EventData).EventData.Data\n| mv-expand bagexpansion=array EventData\n| evaluate bag_unpack(EventData)\n| extend Key = tostring(column_ifexists('@Name', \"\")), Value = column_ifexists('#text', \"\")\n| evaluate pivot(Key, any(Value), TimeGenerated, TargetAccount, Computer, EventSourceName, Channel, Task, Level, EventID, Activity, TargetLogonId, SourceComputerId, EventOriginId, Type, _ResourceId, TenantId, SourceSystem, ManagementGroupName, IpAddress, Account)\n| extend ObjectName = column_ifexists('ObjectName', \"\"), OperationType = column_ifexists('OperationType', \"\"), ObjectValueName = column_ifexists('ObjectValueName', \"\")\n| where ObjectName has 'Schedule\\\\TaskCache\\\\Tree' and ObjectValueName == \"SD\" and OperationType == \"%%1906\"  // %%1906 - Registry value deleted\n| extend HostName = tostring(split(Computer, \".\")[0]), DomainIndex = toint(indexof(Computer, '.'))\n| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)\n| extend AccountName = tostring(split(TargetAccount, @'\\')[1]), AccountNTDomain = tostring(split(TargetAccount, @'\\')[0])\n| extend timestamp = TimeGenerated\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P1D",
        "severity": "High",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "DefenseEvasion"
        ],
        "tags": [
          "Tarrask"
        ],
        "techniques": [
          "T1562"
        ],
        "templateVersion": "1.0.1",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}