Windows Browser Process Creating VHD/VHDX Files via Download
Alerts when a Windows browser process creates files containing .vhd, indicating potential VHD/VHDX staging.
FreeReviewedSigma · Medium · v2
- Product
- windows
- Category
- file_event
- Author
- frack113, Christopher Peacock '@securepeacock', SCYTHE '@scythe_io' (SigmaHQ), DRL 1.1
- Published
- 2021-10-25
- Updated
- 2026-07-31
ATT&CK techniques
Resource DevRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule flags file creation events where a browser process creates a target containing ".vhd" or ".vhdx". Attackers can package payloads in mountable Virtual Hard Disk files to transport content and potentially bypass some defenses. It relies on Windows file event telemetry that includes the creating process image name and the target filename/path.
Reporting behind it
- redcanary.comhttps://redcanary.com/blog/intelligence-insights-october-2021/
- kaspersky.comhttps://www.kaspersky.com/blog/lazarus-vhd-ransomware/36559/
- securelist.comhttps://securelist.com/lazarus-on-the-hunt-for-big-game/97757/
- github.comhttps://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_event/file_event_win_vhd_download_via_browsers.yml
Changelog
v2- v2Candidate ingested via manual entry.2026-07-31
- v1No changelog recorded for this version.2026-07-30
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
windows-browser-processes-creating-vhd-vhdx-files-8468111a
title: Windows Browser Process Creating VHD/VHDX Files via Download
id: 9b19859f-207d-499e-982b-630f8cf6e5d5
status: test
description: This rule flags file creation events where a browser process creates a target containing ".vhd" or ".vhdx". Attackers can package payloads in mountable Virtual Hard Disk files to transport content and potentially bypass some defenses. It relies on Windows file event telemetry that includes the creating process image name and the target filename/path.
references:
- https://redcanary.com/blog/intelligence-insights-october-2021/
- https://www.kaspersky.com/blog/lazarus-vhd-ransomware/36559/
- https://securelist.com/lazarus-on-the-hunt-for-big-game/97757/
- https://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_event/file_event_win_vhd_download_via_browsers.yml
author: frack113, Christopher Peacock '@securepeacock', SCYTHE '@scythe_io', Huntrule Team
date: 2021-10-25
modified: 2023-05-05
tags:
- attack.resource-development
- attack.t1587.001
logsource:
category: file_event
product: windows
detection:
selection:
Image|endswith:
- \brave.exe
- \chrome.exe
- \firefox.exe
- \iexplore.exe
- \maxthon.exe
- \MicrosoftEdge.exe
- \msedge.exe
- \msedgewebview2.exe
- \opera.exe
- \safari.exe
- \seamonkey.exe
- \vivaldi.exe
- \whale.exe
TargetFilename|contains: .vhd
condition: selection
falsepositives:
- Legitimate downloads of ".vhd" files would also trigger this
level: medium
license: DRL-1.1
related:
- id: 8468111a-ef07-4654-903b-b863a80bbc95
type: derived