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.*
Severity: medium
Risk score: 47
Runs every: 5 minutes
Searches indices from: now-6m (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/win_gpo_scheduledtasks.yml
Tags:
- Elastic
- Host
- Windows
- Threat Detection
- Privilege Escalation
- Active Directory
Version: 2 (version history)
Added (Elastic Stack release): 8.0.0
Last modified (Elastic Stack release): 8.1.0
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 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, ánd check the `<Command>` and `<Arguments>` XML tags for any potentially malicious commands and binaries. - If the action is suspicious for the user, check for any other activities done by the user in the last 48 hours. ### 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 - Startup/Logon Script added to Group Policy Object ### Response and Remediation - Immediate response should be taken to validate activity, investigate, and potentially isolate activity to prevent further post-compromise behavior. ## Config The 'Audit Detailed File Share' audit policy is required 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 is required 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
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*))
Threat mapping
editFramework: 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/
Rule version history
edit- Version 2 (8.1.0 release)
-
- Formatting only