Sigma Rule Library

Potential WinAPI Calls Via PowerShell Scripts

Detects usage of WinAPI functions in PowerShell scripts. It may indicate attempts to perform actions such as process injection, token stealing, or other malicious activities that leverage Windows API calls. These techniques are commonly used to evade traditional file-based detections by loading and executing code directly in memory.

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Detection logic

selection_injection

ScriptBlockText|contains|all:
  - VirtualAlloc
  - OpenProcess
  - WriteProcessMemory
  - CreateRemoteThread

selection_token_steal

ScriptBlockText|contains|all:
  - OpenProcessToken
  - LookupPrivilegeValue
  - AdjustTokenPrivileges

selection_duplicate_token

ScriptBlockText|contains|all:
  - OpenProcessToken
  - DuplicateTokenEx
  - CloseHandle

selection_process_write_read

ScriptBlockText|contains|all:
  - WriteProcessMemory
  - VirtualAlloc
  - ReadProcessMemory
  - VirtualFree

selection_local_shellcode_injection

ScriptBlockText|contains|all:
  - VirtualAlloc
  - GetDelegateForFunctionPointer
  - Marshal.Copy

Condition

1 of selection_*

Raw YAML

title: Potential WinAPI Calls Via PowerShell Scripts
id: 03d83090-8cba-44a0-b02f-0b756a050306
related:
    - id: ba3f5c1b-6272-4119-9dbd-0bc8d21c2702
      type: similar
status: test
description: |
    Detects usage of WinAPI functions in PowerShell scripts.
    It may indicate attempts to perform actions such as process injection, token stealing, or other malicious activities that leverage Windows API calls.
    These techniques are commonly used to evade traditional file-based detections by loading and executing code directly in memory.
references:
    - https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse
    - https://github.com/PowerShellMafia/PowerSploit/blob/1980f403ee78234eae4d93b50890d02f827a099f/CodeExecution/Invoke-Shellcode.ps1
    - https://thedfirreport.com/2021/08/29/cobalt-strike-a-defenders-guide/
author: Nasreddine Bencherchali (Nextron Systems), Nikita Nazarov, oscd.community
date: 2020-10-06
modified: 2026-04-29
tags:
    - attack.execution
    - attack.t1059.001
    - attack.t1106
    - attack.stealth
    - attack.t1620
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    # Note: Add more suspicious combinations in the form of different selections
    selection_injection:
        ScriptBlockText|contains|all:
            - 'VirtualAlloc'
            - 'OpenProcess'
            - 'WriteProcessMemory'
            - 'CreateRemoteThread'
    selection_token_steal:
        ScriptBlockText|contains|all:
            - 'OpenProcessToken'
            - 'LookupPrivilegeValue'
            - 'AdjustTokenPrivileges'
    selection_duplicate_token:
        ScriptBlockText|contains|all:
            - 'OpenProcessToken'
            - 'DuplicateTokenEx'
            - 'CloseHandle'
    selection_process_write_read:
        ScriptBlockText|contains|all:
            - 'WriteProcessMemory'
            - 'VirtualAlloc'
            - 'ReadProcessMemory'
            - 'VirtualFree'
    selection_local_shellcode_injection:
        ScriptBlockText|contains|all:
            - 'VirtualAlloc'
            - 'GetDelegateForFunctionPointer'
            - 'Marshal.Copy'
    condition: 1 of selection_*
falsepositives:
    - Unknown
level: high

False positives

  • Unknown

References

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