Sigma rule: Suspicious IO.FileStream

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-9c9064685690, updated 2022-03-05T00:00:00.000Z.

Rule

Title
Suspicious IO.FileStream
Status
test
Level
medium
Author
frack113
Date
2022-01-09
Modified
2022-03-05
File
rules/windows/powershell/powershell_script/posh_ps_susp_iofilestream.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

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.

Log source

product
windows
category
ps_script
definition
Requirements: Script Block Logging must be enabled

Detection

selection:
    ScriptBlockText|contains|all:
        - New-Object
        - IO.FileStream
        - '\\\\.\\'
condition: selection

False positives (as the rule lists them)

  • Legitimate PowerShell scripts

Tags

  • attack.stealth
  • attack.t1070.003

MITRE ATT&CK ids this rule names

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/powershell/powershell_script/posh_ps_susp_iofilestream.yml

Sources and licences

  • SigmaHQ

    "Suspicious IO.FileStream" by frack113 (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/powershell/powershell_script/posh_ps_susp_iofilestream.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: Suspicious IO.FileStream",
entity page, dataset version ref-9c9064685690, updated 2022-03-05T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/70ad982f-67c8-40e0-a955-b920c2fa05cb (accessed 2026-11-03).
Underlying source: SigmaHQ rule 70ad982f-67c8-40e0-a955-b920c2fa05cb, 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.