Linux Suspicious Shell Command Lines for Exploit/Payload Delivery

Detects Linux command-line strings matching wget/piping, payload staging, permission changes, and socat/HTTP server execution patterns.

FreeReviewedSigma · High · v3

Product: linux
Author: Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2017-08-21
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Execution

Recon
Resource Dev
Initial Access
Execution
- T1059.004Unix Shell
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags Linux command lines containing keywords commonly seen in exploit and payload delivery workflows, such as downloading artifacts with wget and executing them via shell or bash, starting local HTTP servers, spawning interactive shells via pty, and using socat for command execution or network bridging. It also matches command fragments associated with common post-exploitation staging and persistence patterns, including base64 decoding into files, setting SUID/permissions on binaries, and writing to system startup locations like /etc/rc.local. The detection relies on process or command-line telemetry that captures the full shell command string to compare against the listed suspicious keyword patterns.

Reporting behind it

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Linux Suspicious Shell Command Lines for Exploit/Payload Delivery

Pivot detection · T1059.004 · 9 related

Changelog

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.

linux-suspicious-shell-command-execution-indicators-in-command-lines-2aa1440c

title: Linux Suspicious Shell Command Lines for Exploit/Payload Delivery
id: 4fc4637f-472b-4548-a671-ef2eee13b209
status: test
description: This rule flags Linux command lines containing keywords commonly seen in exploit and payload delivery workflows, such as downloading artifacts with wget and executing them via shell or bash, starting local HTTP servers, spawning interactive shells via pty, and using socat for command execution or network bridging. It also matches command fragments associated with common post-exploitation staging and persistence patterns, including base64 decoding into files, setting SUID/permissions on binaries, and writing to system startup locations like /etc/rc.local. The detection relies on process or command-line telemetry that captures the full shell command string to compare against the listed suspicious keyword patterns.
references:
  - https://web.archive.org/web/20170319121015/http://www.threatgeek.com/2017/03/widespread-exploitation-attempts-using-cve-2017-5638.html
  - https://github.com/rapid7/metasploit-framework/blob/eb6535009f5fdafa954525687f09294918b5398d/modules/exploits/multi/http/struts_code_exec_exception_delegator.rb
  - http://pastebin.com/FtygZ1cg
  - https://artkond.com/2017/03/23/pivoting-guide/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/linux/builtin/lnx_shell_susp_commands.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2017-08-21
modified: 2021-11-27
tags:
  - attack.execution
  - attack.t1059.004
logsource:
  product: linux
detection:
  keywords:
    - wget * - http* | perl
    - wget * - http* | sh
    - wget * - http* | bash
    - python -m SimpleHTTPServer
    - -m http.server
    - import pty; pty.spawn*
    - socat exec:*
    - socat -O /tmp/*
    - socat tcp-connect*
    - "*echo binary >>*"
    - "*wget *; chmod +x*"
    - "*wget *; chmod 777 *"
    - "*cd /tmp || cd /var/run || cd /mnt*"
    - "*stop;service iptables stop;*"
    - "*stop;SuSEfirewall2 stop;*"
    - chmod 777 2020*
    - "*>>/etc/rc.local"
    - "*base64 -d /tmp/*"
    - "* | base64 -d *"
    - "*/chmod u+s *"
    - "*chmod +s /tmp/*"
    - "*chmod u+s /tmp/*"
    - "* /tmp/haxhax*"
    - "* /tmp/ns_sploit*"
    - nc -l -p *
    - cp /bin/ksh *
    - cp /bin/sh *
    - "* /tmp/*.b64 *"
    - "*/tmp/ysocereal.jar*"
    - "*/tmp/x *"
    - "*; chmod +x /tmp/*"
    - "*;chmod +x /tmp/*"
  condition: keywords
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 2aa1440c-9ae9-4d92-84a7-a9e5f5e31695
    type: derived

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