Linux Network Connection to /bin/bash via Reverse Shell Pattern

Alerts on /bin/bash network connections to non-local destination IPs, consistent with reverse shell behavior.

FreeReviewedSigma · Critical · v3

Product: linux
Category: network_connection
Author: Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2021-10-16
Updated: 2026-07-31

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 network activity where the process image ends with '/bin/bash' and the destination IP is not 127.0.0.1 or 0.0.0.0. Outbound connections initiated by an interactive shell are a common indicator of reverse shell behavior used to establish remote command execution. It relies on telemetry that correlates the executable path (process image) with destination IP for Linux network connection events.

Reporting behind it

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Linux Network Connection to /bin/bash via Reverse Shell Pattern

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-reverse-shell-via-bin-bash-connecting-to-external-ips-83dcd9f6

title: Linux Network Connection to /bin/bash via Reverse Shell Pattern
id: 43191603-b1b2-4d15-8bdb-3084b295972f
status: test
description: This rule flags network activity where the process image ends with '/bin/bash' and the destination IP is not 127.0.0.1 or 0.0.0.0. Outbound connections initiated by an interactive shell are a common indicator of reverse shell behavior used to establish remote command execution. It relies on telemetry that correlates the executable path (process image) with destination IP for Linux network connection events.
references:
  - https://github.com/swisskyrepo/PayloadsAllTheThings/blob/d9921e370b7c668ee8cc42d09b1932c1b98fa9dc/Methodology%20and%20Resources/Reverse%20Shell%20Cheatsheet.md
  - https://github.com/SigmaHQ/sigma/blob/master/rules/linux/network_connection/net_connection_lnx_back_connect_shell_dev.yml
author: Florian Roth (Nextron Systems), Huntrule Team
date: 2021-10-16
modified: 2022-12-25
tags:
  - attack.execution
  - attack.t1059.004
logsource:
  product: linux
  category: network_connection
detection:
  selection:
    Image|endswith: /bin/bash
  filter:
    DestinationIp:
      - 127.0.0.1
      - 0.0.0.0
  condition: selection and not filter
falsepositives:
  - Unknown
level: critical
license: DRL-1.1
related:
  - id: 83dcd9f6-9ca8-4af7-a16e-a1c7a6b51871
    type: derived

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