IMPORTANT: No additional bug fixes or documentation updates
will be released for this version. For the latest information, see the
current release documentation.
Scheduled Task Execution at Scale via GPO
editScheduled Task Execution at Scale via GPO
editDetects 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.*
- logs-windows.*
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:
- https://github.com/atc-project/atc-data/blob/master/docs/Logging_Policies/LP_0025_windows_audit_directory_service_changes.md
- https://github.com/atc-project/atc-data/blob/f2bbb51ecf68e2c9f488e3c70dcdd3df51d2a46b/docs/Logging_Policies/LP_0029_windows_audit_detailed_file_share.md
- https://labs.f-secure.com/tools/sharpgpoabuse
- https://twitter.com/menasec1/status/1106899890377052160
- https://github.com/SigmaHQ/sigma/blob/master/rules/windows/builtin/security/win_gpo_scheduledtasks.yml
Tags:
- Domain: Endpoint
- OS: Windows
- Use Case: Threat Detection
- Tactic: Privilege Escalation
- Tactic: Lateral Movement
- Data Source: Active Directory
- Resources: Investigation Guide
- Use Case: Active Directory Monitoring
Version: 109
Rule authors:
- Elastic
Rule license: Elastic License v2
Investigation guide
edit## 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 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 or binaries. - Investigate other alerts associated with the user/host during the past 48 hours. - Scope which objects may be compromised by retrieving information about which objects are controlled by the GPO. ### 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. - Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector. - Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the mean time to respond (MTTR).
Rule query
edit(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
-
Tactic:
- Name: Privilege Escalation
- ID: TA0004
- Reference URL: https://attack.mitre.org/tactics/TA0004/
-
Technique:
- Name: Scheduled Task/Job
- ID: T1053
- Reference URL: https://attack.mitre.org/techniques/T1053/
-
Sub-technique:
- Name: Scheduled Task
- ID: T1053.005
- Reference URL: https://attack.mitre.org/techniques/T1053/005/
-
Technique:
- Name: Domain Policy Modification
- ID: T1484
- Reference URL: https://attack.mitre.org/techniques/T1484/
-
Sub-technique:
- Name: Group Policy Modification
- ID: T1484.001
- Reference URL: https://attack.mitre.org/techniques/T1484/001/
-
Tactic:
- Name: Lateral Movement
- ID: TA0008
- Reference URL: https://attack.mitre.org/tactics/TA0008/
-
Technique:
- Name: Lateral Tool Transfer
- ID: T1570
- Reference URL: https://attack.mitre.org/techniques/T1570/