Scheduled Task Hide

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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

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

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

ARM