Windows: File Download via curl.exe with -O/--remote-name or --output

Flags curl.exe with download-oriented options (-O, --remote-name, --output) to spot likely file retrieval on Windows.

FreeReviewedSigma · Medium · v5

Product: windows
Category: process_creation
Author: Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2022-07-05
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 identifies Windows process executions of curl.exe where the command line includes curl’s file-writing options for downloads (-O/--remote-name or --output). This matters because attackers commonly use curl to retrieve payloads or stage files for later execution. The detection relies on process creation telemetry with the process image path and full command line.

Reporting behind it

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Windows: File Download via curl.exe with -O/--remote-name or --output

Pivot detection · T1105 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
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-curl-exe-file-download-via-o-remote-name-or-output-9a517fca

title: "Windows: File Download via curl.exe with -O/--remote-name or --output"
id: c66b93b7-7381-4f4b-a5c8-a6c2e6773cff
related:
  - id: bbeaed61-1990-4773-bf57-b81dbad7db2d
    type: derived
  - id: e218595b-bbe7-4ee5-8a96-f32a24ad3468
    type: derived
  - id: 9a517fca-4ba3-4629-9278-a68694697b81
    type: derived
status: test
description: This rule identifies Windows process executions of curl.exe where the command line includes curl’s file-writing options for downloads (-O/--remote-name or --output). This matters because attackers commonly use curl to retrieve payloads or stage files for later execution. The detection relies on process creation telemetry with the process image path and full command line.
references:
  - https://web.archive.org/web/20200128160046/https://twitter.com/reegun21/status/1222093798009790464
  - https://github.com/SigmaHQ/sigma/blob/master/rules-threat-hunting/windows/process_creation/proc_creation_win_curl_download.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2022-07-05
modified: 2023-02-21
tags:
  - attack.command-and-control
  - attack.t1105
  - detection.threat-hunting
logsource:
  category: process_creation
  product: windows
detection:
  selection_img:
    - Image|endswith: \curl.exe
    - Product: The curl executable
  selection_remote:
    CommandLine|contains:
      - " -O"
      - --remote-name
      - --output
  condition: all of selection_*
falsepositives:
  - Scripts created by developers and admins
  - Administrative activity
  - The "\Git\usr\bin\sh.exe" process uses the "--output" flag to download a specific file in the temp directory with the pattern "gfw-httpget-xxxxxxxx.txt "
level: medium
license: DRL-1.1

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