Linux Suspicious React or Next.js Child Process

name: Linux Suspicious React or Next.js Child Process
id: cda04e9c-1950-43ab-87d6-e333a3d7f107
version: 2
date: '2026-03-10'
author: Nasreddine Bencherchali, Splunk
status: production
type: TTP
description: |
    This analytic detects Linux processes such as sh, bash, and common Linux LOLBINs being spawned by React or Next.js application servers.
    In the context of CVE-2025-55182 / React2Shell / CVE-2025-66478 for Next.js, successful exploitation can lead to arbitrary JavaScript execution on the server, which in turn is commonly used to invoke Node's child_process APIs (for example child_process.execSync) to run OS-level commands.
    Public proof-of-concept payloads and observed in-the-wild exploit traffic show patterns where the vulnerable React Server Components handler triggers process.mainModule.require('child_process').execSync() to execute binaries such as ping, curl, or arbitrary shells on the underlying host.
    This detection focuses on suspicious child processes where a Next/React server process spawns an uncommon process.
    Such activity might be a strong indicator of exploitation of the aforementioned vulnerability.
data_source:
    - Sysmon for Linux EventID 1
search: |
    | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime
      from datamodel=Endpoint.Processes
      where
        Processes.parent_process_name = "node"
        Processes.parent_process IN (
          "*--experimental-https*",
          "*--experimental-next-config-strip-types*",
          "*/node_modules/next*",
          "*next dev*",
          "*next start*",
          "*node_modules/.bin*",
          "*react-scripts start*",
          "*start-server.js*"
        )
        AND (
          Processes.process_name IN (
            "awk",
            "gawk",
            "ifconfig",
            "lua",
            "nc",
            "ncat",
            "netcat",
            "openssl",
            "perl",
            "php",
            "python",
            "python2",
            "python3",
            "ruby",
            "socat",
            "telnet"
          )
          OR (
            Processes.process_name IN ("curl", "wget")
            Processes.process = "*|*"
          )
          OR (
            Processes.process_name IN (
              "bash",
              "dash",
              "sh"
            )
            NOT Processes.process = "*-c*"
          )
          OR (
            Processes.process_name IN (
              "bash",
              "dash",
              "ksh",
              "sh",
              "zsh"
            )
            Processes.process IN (
              "*/dev/tcp/*",
              "*/dev/udp/*",
              "*0>&1*",
              "*curl*",
              "*exec *>&*",
              "*fsockopen*",
              "*ifconfig*",
              "*mkfifo*",
              "*nc *",
              "*ncat*",
              "*netcat*",
              "*proc_open*",
              "*s_client*",
              "*socat*",
              "*socket*",
              "*subprocess*",
              "*TCPSocket*",
              "*wget*"
            )
          )
        )

    by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
       Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
       Processes.parent_process_name Processes.parent_process_path Processes.process
       Processes.process_exec Processes.process_guid Processes.process_hash Processes.process_id
       Processes.process_integrity_level Processes.process_name Processes.process_path
       Processes.user Processes.user_id Processes.vendor_product

    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `linux_suspicious_react_or_next_js_child_process_filter`
how_to_implement: |
    The detection is based on data that originates from Endpoint Detection and Response (EDR) agents.
    These agents are designed to provide security-related telemetry from the endpoints where the agent is installed.
    To implement this search, you must ingest logs that contain the process GUID, process name, and parent process.
    Additionally, you must ingest complete command-line executions.
    These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model.
    Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: |
    Rare false positives might show up from child processes such as sh. Apply additional filters as needed.
references:
    - https://react.dev/blog/2025/12/03/critical-security-vulnerability-in-react-server-components
    - https://nextjs.org/blog/CVE-2025-66478
    - https://nvd.nist.gov/vuln/detail/CVE-2025-55182
    - https://gist.github.com/maple3142/48bc9393f45e068cf8c90ab865c0f5f3
    - https://www.wiz.io/blog/critical-vulnerability-in-react-cve-2025-55182
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168  | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: A Node-based server process ($parent_process_name$) on Linux spawned the child process $process_name$ with command-line $process$ on host $dest$ by user $user$, which may indicate remote code execution via React Server Components (CVE-2025-55182 / React2Shell) or abuse of a similar Node.js RCE vector.
    risk_objects:
        - field: user
          type: user
          score: 50
        - field: dest
          type: system
          score: 50
    threat_objects:
        - field: parent_process_name
          type: process
        - field: process_name
          type: process
        - field: process
          type: process
tags:
    analytic_story:
        - React2Shell
    asset_type: Endpoint
    mitre_attack_id:
        - T1190
        - T1059.004
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/emerging_threats/react2shell/react2shell_linux.log
          source: Syslog:Linux-Sysmon/Operational
          sourcetype: sysmon:linux