Windows Browser Process Spawned with Inline URL Pointing to Suspicious File Extension

Flags Windows browser processes launched with an inline HTTP URL pointing to files with suspicious extensions.

FreeReviewedSigma · Medium · v2

Product: windows
Category: process_creation
Author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2022-01-11
Updated: 2026-07-31

ATT&CK techniques

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
- T1105Ingress Tool Transfer
Exfiltration
Impact

What it detects

This rule flags process creation where a common Windows browser executable is launched with a command-line argument containing an HTTP URL and ending in a potentially suspicious file extension (e.g., .exe, .dll, .ps1, .zip). Such behavior can be abused to coerce the browser into downloading arbitrary content or to reduce user visibility (for example, by using browser launch parameters). Telemetry relies on Windows process creation events including the initiating executable image path/name and the full command line arguments.

Reporting behind it

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Windows Browser Process Spawned with Inline URL Pointing to Suspicious File Extension

Pivot detection · T1105 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No 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-process-file-download-via-inline-url-and-suspicious-extension-94771a71

title: Windows Browser Process Spawned with Inline URL Pointing to Suspicious File Extension
id: fc9ebdb2-821d-4934-ba59-09b9b5a57ee4
status: test
description: This rule flags process creation where a common Windows browser executable is launched with a command-line argument containing an HTTP URL and ending in a potentially suspicious file extension (e.g., .exe, .dll, .ps1, .zip). Such behavior can be abused to coerce the browser into downloading arbitrary content or to reduce user visibility (for example, by using browser launch parameters). Telemetry relies on Windows process creation events including the initiating executable image path/name and the full command line arguments.
references:
  - https://twitter.com/mrd0x/status/1478116126005641220
  - https://lolbas-project.github.io/lolbas/Binaries/Msedge/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_browsers_inline_file_download.yml
author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2022-01-11
modified: 2025-10-27
tags:
  - attack.command-and-control
  - attack.t1105
logsource:
  category: process_creation
  product: windows
detection:
  selection_img:
    Image|endswith:
      - \brave.exe
      - \chrome.exe
      - \msedge.exe
      - \opera.exe
      - \vivaldi.exe
  selection_http:
    CommandLine|contains: http
  selection_extensions:
    - CommandLine|endswith:
        - .7z
        - .dat
        - .dll
        - .exe
        - .hta
        - .ps1
        - .psm1
        - .txt
        - .vbe
        - .vbs
        - .zip
    - CommandLine|contains:
        - .7z"
        - .dat"
        - .dll"
        - .hta"
        - .ps1"
        - .psm1"
        - .txt"
        - .vbe"
        - .vbs"
        - .zip"
  condition: all of selection_*
falsepositives:
  - Unknown
level: medium
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_browsers_inline_file_download/info.yml
license: DRL-1.1
related:
  - id: 94771a71-ba41-4b6e-a757-b531372eaab6
    type: derived

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