IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.
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Elastic Docs ›Elastic Security Solution [7.16] ›Downloadable rule update v0.16.2

Scheduled Task Execution at Scale via GPO

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Scheduled Task Execution at Scale via GPO

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Detects the modification of Group Policy Object attributes to execute a scheduled task in the objects controlled by the GPO.

Rule type: query

Rule indices:

  • winlogbeat-*
  • logs-system.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: None (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Privilege Escalation
  • Active Directory

Version: 3

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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## Triage and analysis

### Investigating Scheduled Task Execution at Scale via GPO

Group Policy Objects (GPOs) can be used by attackers to execute scheduled tasks at scale to compromise objects controlled
by a given GPO. This is done by changing the contents of the `<GPOPath>\Machine\Preferences\ScheduledTasks\ScheduledTasks.xml`
file.

#### Possible investigation steps

- This attack abuses a legitimate mechanism of the Active Directory, so it is important to determine whether the activity
is legitimate and the administrator is authorized to perform this operation.
- Retrieve the contents of the `ScheduledTasks.xml` file, and check the `<Command>` and `<Arguments>` XML tags for any
potentially malicious commands and binaries.
- Investigate other alerts related to the user/host in the last 48 hours.
- Scope which objects have been affected.

### False positive analysis

- Verify if the execution is allowed and done under change management, and if the execution is legitimate.

### Related rules

- Group Policy Abuse for Privilege Addition - b9554892-5e0e-424b-83a0-5aef95aa43bf
- Startup/Logon Script added to Group Policy Object - 16fac1a1-21ee-4ca6-b720-458e3855d046

### Response and remediation

- Initiate the incident response process based on the outcome of the triage.
- The investigation and containment must be performed in every computer controlled by the GPO, where necessary.
- Remove the script from the GPO.
- Check if other GPOs have suspicious scheduled tasks attached.

## Config

The 'Audit Detailed File Share' audit policy must be configured (Success Failure).
Steps to implement the logging policy with with Advanced Audit Configuration:

```
Computer Configuration >
Policies >
Windows Settings >
Security Settings >
Advanced Audit Policies Configuration >
Audit Policies >
Object Access >
Audit Detailed File Share (Success,Failure)
```

The 'Audit Directory Service Changes' audit policy must be configured (Success Failure).
Steps to implement the logging policy with with Advanced Audit Configuration:

```
Computer Configuration >
Policies >
Windows Settings >
Security Settings >
Advanced Audit Policies Configuration >
Audit Policies >
DS Access >
Audit Directory Service Changes (Success,Failure)
```

Rule query

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(event.code: "5136" and winlog.event_data.AttributeLDAPDisplayName:("gPCMachineExtensionNames" or "gPCUserExtensionNames") and
   winlog.event_data.AttributeValue:(*CAB54552-DEEA-4691-817E-ED4A4D1AFC72* and *AADCED64-746C-4633-A97C-D61349046527*))
or
(event.code: "5145" and winlog.event_data.ShareName: "\\\\*\\SYSVOL" and winlog.event_data.RelativeTargetName: *ScheduledTasks.xml and
  (message: WriteData or winlog.event_data.AccessList: *%%4417*))

Framework: MITRE ATT&CKTM

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