Scheduled Task Hide | Microsoft Sentinel Analytic Rules

Back


Id	6dd2629c-534b-4275-8201-d7968b4fa77e
Rulename	Scheduled Task Hide
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/
Severity	High
Tactics	DefenseEvasion
Techniques	T1562
Required data connectors	SecurityEvents WindowsSecurityEvents
Kind	Scheduled
Query frequency	1d
Query period	1d
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Windows%20Security%20Events/Analytic%20Rules/ScheduleTaskHide.yaml
Version	1.0.1
Arm template	6dd2629c-534b-4275-8201-d7968b4fa77e.json

KQL

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

YAML

tags:
- Tarrask
version: 1.0.1
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Windows%20Security%20Events/Analytic%20Rules/ScheduleTaskHide.yaml
triggerThreshold: 0
requiredDataConnectors:
- dataTypes:
  - SecurityEvent
  connectorId: SecurityEvents
- dataTypes:
  - SecurityEvent
  connectorId: WindowsSecurityEvents
tactics:
- DefenseEvasion
relevantTechniques:
- T1562
kind: Scheduled
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
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/'
triggerOperator: gt
status: Available
queryFrequency: 1d
id: 6dd2629c-534b-4275-8201-d7968b4fa77e
name: Scheduled Task Hide
severity: High
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
queryPeriod: 1d

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/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%20Security%20Events/Analytic%20Rules/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 - 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"
    }
  ]
}