Linux wget downloads to /tmp using explicit output options

Alerts on wget commands writing output to /tmp using -O or --output-document.

FreeReviewedSigma · Medium · v2

Product: linux
Category: process_creation
Author: Joseliyo Sanchez, @Joseliyo_Jstnk (SigmaHQ), DRL 1.1
Published: 2023-06-02
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 Linux process executions where the image path ends with "/wget" and the command line includes output targeting indicators. It further requires explicit output-document usage (or an equivalent "-O" form) and a destination path containing "/tmp/", which can be consistent with staging files for later execution or command-and-control behavior. Telemetry relies on process creation events that include the executable path and full command line.

Reporting behind it

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Linux wget downloads to /tmp using explicit output options

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.

linux-process-creation-wget-downloaded-files-to-tmp-cf610c15

title: Linux wget downloads to /tmp using explicit output options
id: f591d06b-5133-4517-aa14-a74761e75edb
status: test
description: This rule identifies Linux process executions where the image path ends with "/wget" and the command line includes output targeting indicators. It further requires explicit output-document usage (or an equivalent "-O" form) and a destination path containing "/tmp/", which can be consistent with staging files for later execution or command-and-control behavior. Telemetry relies on process creation events that include the executable path and full command line.
references:
  - https://blogs.jpcert.or.jp/en/2023/05/gobrat.html
  - https://jstnk9.github.io/jstnk9/research/GobRAT-Malware/
  - https://www.virustotal.com/gui/file/60bcd645450e4c846238cf0e7226dc40c84c96eba99f6b2cffcd0ab4a391c8b3/detection
  - https://www.virustotal.com/gui/file/3e44c807a25a56f4068b5b8186eee5002eed6f26d665a8b791c472ad154585d1/detection
  - https://github.com/SigmaHQ/sigma/blob/master/rules/linux/process_creation/proc_creation_lnx_wget_download_suspicious_directory.yml
author: Joseliyo Sanchez, @Joseliyo_Jstnk, Huntrule Team
date: 2023-06-02
tags:
  - attack.command-and-control
  - attack.t1105
logsource:
  category: process_creation
  product: linux
detection:
  selection_img:
    Image|endswith: /wget
  selection_output:
    - CommandLine|re: \s-O\s
    - CommandLine|contains: --output-document
  selection_path:
    CommandLine|contains: /tmp/
  condition: all of selection_*
falsepositives:
  - Unknown
level: medium
license: DRL-1.1
related:
  - id: cf610c15-ed71-46e1-bdf8-2bd1a99de6c4
    type: derived

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