Linux Suspicious Child Process from Node.js - React2Shell

title: Linux Suspicious Child Process from Node.js - React2Shell
id: c70834fa-fb9d-4aa0-9e7d-45ceed36f3f7
related:
    - id: 271de298-cc0e-4842-acd8-079a0a99ea65
      type: similar
status: experimental
description: |
    Detects suspicious child processes spawned from Node.js server processes on Linux systems, potentially indicating remote code execution exploitation such as CVE-2025-55182 (React2Shell).
    This rule particularly looks for exploitation of vulnerability on Node.js Servers where attackers abuse Node.js child_process module to execute arbitrary system commands.
    When execSync() or exec() is used, the command line often includes a shell invocation followed by suspicious commands or scripts (e.g., /bin/sh -c <malicious-command>).
    For other methods, the Image field will show the spawned process directly.
references:
    - https://github.com/msanft/CVE-2025-55182
    - https://nodejs.org/api/child_process.html#class-childprocess
    - https://gist.github.com/swachchhanda000/a0228130f86a2dedfbcebb415b47f870
    - https://github.com/nasbench/Misc-Research/blob/2f651ede832ab34027a7ba005b63bb78f1ade378/Other/React-Next-Child-Processes-Notes.md
author: Swachchhanda Shrawan Poudel (Nextron Systems), Nasreddine Bencherchali
date: 2025-12-05
tags:
    - attack.execution
    - attack.t1059
    - attack.initial-access
    - attack.t1190
    - detection.emerging-threats
    - cve.2025-55182
logsource:
    category: process_creation
    product: linux
detection:
    selection_parent:
        ParentImage|endswith: '/node'
        ParentCommandLine|contains:
            - '--experimental-https'
            - '--experimental-next-config-strip-types'
            - '/node_modules/next'
            - 'next dev'
            - 'next start'
            - 'node_modules/.bin'
            - 'react-scripts start'
            - 'start-server.js'
    selection_generic_child_img:
        # Observed when child_process.spawn(), child_process.exec(), child_process.execFile(), or child_process.fork() method is used to spawn suspicious processes in exploit
        - Image|endswith:
              - '/busybox'
              - '/cat'
              - '/curl'
              - '/dash'
              - '/dig'
              - '/head'
              - '/id'
              - '/ifconfig'
              - '/ip'
              - '/java'
              - '/less'
              - '/lua'
              - '/more'
              - '/nc'
              - '/ncat'
              - '/netcat'
              - '/netstat'
              - '/nslookup'
              - '/perl'
              - '/ping'
              - '/python'
              - '/python2'
              - '/ruby'
              - '/socat'
              - '/tail'
              - '/wget'
              - '/whoami'
        - Image|contains: '/python'
    selection_generic_child_cli:
        # Observed when child_process.execSync() is used to spawn suspicious processes
        # Reference: https://nodejs.org/api/child_process.html#child_processexecsynccommand-options
        # By default, the cli will look something like `/bin/sh -c .......`
        CommandLine|contains:
            - '/dev/tcp/'
            - '/dev/udp/'
            - '/etc/hosts'
            - '/etc/passwd'
            - '/etc/shadow'
            - 'base64'
            - 'cat '
            - 'curl'
            - 'dig'
            - 'ifconfig'
            - 'IO::Socket::INET'
            - 'java'
            - 'less '
            - 'lua'
            - 'mkfifo '
            - 'more'
            - 'nc '
            - 'ncat'
            - 'netcat'
            - 'netstat'
            - 'nslookup'
            - 'perl'
            - 'php'
            - 'ping'
            - 'ps -ef'
            - 'ps aux'
            - 'python'
            - 'rcat'
            - 'ruby'
            - 'sh -i 2>&1'
            - '-c id'
            - 'socat'
            - 'uname'
            - 'wget'
            - 'whoami'
    selection_specific_sh:
        Image|endswith: '/sh'
    selection_specific_cli:
        Image|endswith: '-c'
    filter_main_default_shell_flag:
        Image|endswith: '-c'
    condition:
        selection_parent and
        (
            1 of selection_generic_*
            or
            (selection_specific_sh and not filter_main_default_shell_flag)
            or
            (all of selection_specific_* and selection_generic_child_cli)
        )
falsepositives:
    - Unknown
level: high