Sigma rule: VHD Image Download Via Browser

Rule

Title

VHD Image Download Via Browser

Status

test

Level

medium

Author

frack113, Christopher Peacock '@securepeacock', SCYTHE '@scythe_io'

Date

2021-10-25

Modified

2023-05-05

File

rules/windows/file/file_event/file_event_win_vhd_download_via_browsers.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects creation of ".vhd"/".vhdx" files by browser processes.
Malware can use mountable Virtual Hard Disk ".vhd" files to encapsulate payloads and evade security controls.

Log source

product

windows

category

file_event

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'
    # We don't use "endswith" to also match with ADS logs and ".vhdx". Example: "TargetFilename: C:\Users\xxx\Downloads\windows.vhd:Zone.Identifier"
    TargetFilename|contains: '.vhd'
condition: selection

False positives (as the rule lists them)

• Legitimate downloads of ".vhd" files would also trigger this

Tags

• attack.resource-development
• attack.t1587.001

MITRE ATT&CK ids this rule names

• T1587.001

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/

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/file/file_event/file_event_win_vhd_download_via_browsers.yml