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PowerShell Script Dropped Via PowerShell.EXE

Detects PowerShell creating a PowerShell file (.ps1). While often times this behavior is benign, sometimes it can be a sign of a dropper script trying to achieve persistence.

Detection Query

selection:
  Image|endswith:
    - \powershell.exe
    - \pwsh.exe
  TargetFilename|endswith: .ps1
filter_main_psscriptpolicytest:
  TargetFilename|contains: __PSScriptPolicyTest_
filter_main_appdata:
  TargetFilename|startswith: C:\Users\
  TargetFilename|contains: \AppData\Local\Temp\
filter_main_windows_temp:
  TargetFilename|startswith: C:\Windows\Temp\
condition: selection and not 1 of filter_main_*

Author

frack113

Created

2023-05-09

Data Sources

windowsFile Events

Platforms

windows

References

https://www.zscaler.com/blogs/security-research/onenote-growing-threat-malware-distribution

Tags

attack.persistence

Raw Content

title: PowerShell Script Dropped Via PowerShell.EXE
id: 576426ad-0131-4001-ae01-be175da0c108
status: test
description: Detects PowerShell creating a PowerShell file (.ps1). While often times this behavior is benign, sometimes it can be a sign of a dropper script trying to achieve persistence.
references:
    - https://www.zscaler.com/blogs/security-research/onenote-growing-threat-malware-distribution
author: frack113
date: 2023-05-09
tags:
    - attack.persistence
logsource:
    product: windows
    category: file_event
detection:
    selection:
        Image|endswith:
            - '\powershell.exe'
            - '\pwsh.exe'
        TargetFilename|endswith: '.ps1'
    filter_main_psscriptpolicytest:
        TargetFilename|contains: '__PSScriptPolicyTest_'
    filter_main_appdata:
        TargetFilename|startswith: 'C:\Users\'
        TargetFilename|contains: '\AppData\Local\Temp\'
    filter_main_windows_temp:
        TargetFilename|startswith: 'C:\Windows\Temp\'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - False positives will differ depending on the environment and scripts used. Apply additional filters accordingly.
level: low