Suspicious IO.FileStream — Sigma Rule

Rule metadata and linked tags

Author: frack113. Source status: test; severity: medium. Source dates: 2022-01-09 / 2022-03-05.

{
  "product": "windows",
  "category": "ps_script",
  "definition": "Requirements: Script Block Logging must be enabled"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 1bd19b7fa0110e787749764cae8e08d1b88cbc84ac169ecd676b90c4471a5332

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Suspicious IO.FileStream
id: 70ad982f-67c8-40e0-a955-b920c2fa05cb
status: test
description: Open a handle on the drive volume via the \\.\ DOS device path specifier and perform direct access read of the first few bytes of the volume.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1006/T1006.md
author: frack113
date: 2022-01-09
modified: 2022-03-05
tags:
    - attack.stealth
    - attack.t1070.003
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        ScriptBlockText|contains|all:
            - New-Object
            - IO.FileStream
            - '\\\\.\\'
    condition: selection
falsepositives:
    - Legitimate PowerShell scripts
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate PowerShell scripts

Source references

• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1006/T1006.md