Potential WinAPI Calls Via PowerShell Scripts

Status: test
Severity: high
Log source: category ps_script, product windows
Author: Nasreddine Bencherchali (Nextron Systems), Nikita Nazarov, oscd.community
Source: github.com/SigmaHQ/sigma

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.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell `T1106` Native API
Stealth	`T1620` Reflective Code Loading

Telemetry coverage

Provider	Record / event type
PowerShell	Event ID 4104: Creating Scriptblock text (MessageNumber of MessageTotal).

Rule body

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

Stages and Predicates

Stage 0: `condition`

1 of selection_*

Stage 1: `selection_injection`

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

Stage 2: `selection_token_steal`

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

Stage 3: `selection_duplicate_token`

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

Stage 4: `selection_process_write_read`

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

Stage 5: `selection_local_shellcode_injection`

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

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`ScriptBlockText`	match	`AdjustTokenPrivileges` corpus 3 (sigma 3) `CloseHandle` corpus 2 (sigma 2) `CreateRemoteThread` corpus 2 (sigma 2) `DuplicateTokenEx` corpus 2 (sigma 2) `GetDelegateForFunctionPointer` corpus 3 (sigma 3) `LookupPrivilegeValue` `Marshal.Copy` `OpenProcess` corpus 2 (sigma 2) `OpenProcessToken` corpus 2 (sigma 2) `ReadProcessMemory` corpus 2 (sigma 2) `VirtualAlloc` corpus 2 (sigma 2) `VirtualFree` corpus 2 (sigma 2) `WriteProcessMemory` corpus 2 (sigma 2)	`field:"ScriptBlockText" kind:match`

Potential WinAPI Calls Via PowerShell Scripts

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_injection

Stage 2: selection_token_steal

Stage 3: selection_duplicate_token

Stage 4: selection_process_write_read