Sigma rule: PowerShell Base64 Encoded WMI Classes

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-2cd61fc1fda8, updated 2023-01-30T00:00:00.000Z.

Rule

Title
PowerShell Base64 Encoded WMI Classes
Status
test
Level
high
Author
Christian Burkard (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
Date
2023-01-30
File
rules/windows/process_creation/proc_creation_win_powershell_base64_wmi_classes.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects calls to base64 encoded WMI class such as "Win32_ShadowCopy", "Win32_ScheduledJob", etc.

Log source

product
windows
category
process_creation

Detection

selection_img:
    - Image|endswith:
          - '\powershell.exe'
          - '\pwsh.exe'
    - OriginalFileName:
          - 'PowerShell.EXE'
          - 'pwsh.dll'
selection_cli_shadowcopy:
    # Win32_ShadowCopy
    CommandLine|contains:
        - 'VwBpAG4AMwAyAF8AUwBoAGEAZABvAHcAYwBvAHAAeQ'
        - 'cAaQBuADMAMgBfAFMAaABhAGQAbwB3AGMAbwBwAHkA'
        - 'XAGkAbgAzADIAXwBTAGgAYQBkAG8AdwBjAG8AcAB5A'
        - 'V2luMzJfU2hhZG93Y29we'
        - 'dpbjMyX1NoYWRvd2NvcH'
        - 'XaW4zMl9TaGFkb3djb3B5'
selection_cli_scheduledJob:
    # Win32_ScheduledJob
    CommandLine|contains:
        - 'VwBpAG4AMwAyAF8AUwBjAGgAZQBkAHUAbABlAGQASgBvAGIA'
        - 'cAaQBuADMAMgBfAFMAYwBoAGUAZAB1AGwAZQBkAEoAbwBiA'
        - 'XAGkAbgAzADIAXwBTAGMAaABlAGQAdQBsAGUAZABKAG8AYg'
        - 'V2luMzJfU2NoZWR1bGVkSm9i'
        - 'dpbjMyX1NjaGVkdWxlZEpvY'
        - 'XaW4zMl9TY2hlZHVsZWRKb2'
selection_cli_process:
    # Win32_Process
    CommandLine|contains:
        - 'VwBpAG4AMwAyAF8AUAByAG8AYwBlAHMAcw'
        - 'cAaQBuADMAMgBfAFAAcgBvAGMAZQBzAHMA'
        - 'XAGkAbgAzADIAXwBQAHIAbwBjAGUAcwBzA'
        - 'V2luMzJfUHJvY2Vzc'
        - 'dpbjMyX1Byb2Nlc3'
        - 'XaW4zMl9Qcm9jZXNz'
selection_cli_useraccount:
    # Win32_UserAccount
    CommandLine|contains:
        - 'VwBpAG4AMwAyAF8AVQBzAGUAcgBBAGMAYwBvAHUAbgB0A'
        - 'cAaQBuADMAMgBfAFUAcwBlAHIAQQBjAGMAbwB1AG4AdA'
        - 'XAGkAbgAzADIAXwBVAHMAZQByAEEAYwBjAG8AdQBuAHQA'
        - 'V2luMzJfVXNlckFjY291bn'
        - 'dpbjMyX1VzZXJBY2NvdW50'
        - 'XaW4zMl9Vc2VyQWNjb3Vud'
selection_cli_loggedonuser:
    # Win32_LoggedOnUser
    CommandLine|contains:
        - 'VwBpAG4AMwAyAF8ATABvAGcAZwBlAGQATwBuAFUAcwBlAHIA'
        - 'cAaQBuADMAMgBfAEwAbwBnAGcAZQBkAE8AbgBVAHMAZQByA'
        - 'XAGkAbgAzADIAXwBMAG8AZwBnAGUAZABPAG4AVQBzAGUAcg'
        - 'V2luMzJfTG9nZ2VkT25Vc2Vy'
        - 'dpbjMyX0xvZ2dlZE9uVXNlc'
        - 'XaW4zMl9Mb2dnZWRPblVzZX'
condition: selection_img and 1 of selection_cli_*

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.execution
  • attack.stealth
  • attack.t1059.001
  • attack.t1027

MITRE ATT&CK ids this rule names

Related rules

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_powershell_base64_wmi_classes.yml

Sources and licences

  • SigmaHQ

    "PowerShell Base64 Encoded WMI Classes" by Christian Burkard (Nextron Systems), Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_powershell_base64_wmi_classes.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: PowerShell Base64 Encoded WMI Classes",
entity page, dataset version ref-2cd61fc1fda8, updated 2023-01-30T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/1816994b-42e1-4fb1-afd2-134d88184f71 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 1816994b-42e1-4fb1-afd2-134d88184f71, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.