Scheduled Task Hide
| 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 Security Events/Analytic Rules/ScheduleTaskHide.yaml |
| Version | 1.0.1 |
| Arm template | 6dd2629c-534b-4275-8201-d7968b4fa77e.json |
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
severity: High
relevantTechniques:
- T1562
queryFrequency: 1d
kind: Scheduled
version: 1.0.1
name: Scheduled Task Hide
triggerOperator: gt
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/'
queryPeriod: 1d
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
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
tactics:
- DefenseEvasion
status: Available
triggerThreshold: 0
tags:
- Tarrask
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Windows Security Events/Analytic Rules/ScheduleTaskHide.yaml
id: 6dd2629c-534b-4275-8201-d7968b4fa77e
requiredDataConnectors:
- dataTypes:
- SecurityEvent
connectorId: SecurityEvents
- dataTypes:
- SecurityEvent
connectorId: WindowsSecurityEvents
{
"$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/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",
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"DefenseEvasion"
],
"tags": [
"Tarrask"
],
"techniques": [
"T1562"
],
"templateVersion": "1.0.1",
"triggerOperator": "GreaterThan",
"triggerThreshold": 0
},
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
}
]
}