Web or Application Server Spawning a Shell

name: Web or Application Server Spawning a Shell
id: 8fdb41ad-091c-4d7a-af1d-9123fe94b539
version: 5
creation_date: '2021-12-13'
modification_date: '2026-05-13'
author: Michael Haag, Nasreddine Bencherchali, Splunk
status: production
type: TTP
description: |
    The following analytic detects instances where Java, or Tomcat
    processes spawn a Linux shell, which may indicate exploitation attempts, such as
    those related to CVE-2021-44228 (Log4Shell). This detection leverages Endpoint Detection
    and Response (EDR) telemetry, focusing on process names and parent-child process
    relationships. This activity is significant as it can signify a compromised Java
    application, potentially leading to unauthorized shell access. If confirmed malicious,
    attackers could execute arbitrary commands, escalate privileges, or maintain persistent
    access, posing a severe threat to the environment.
data_source:
    - Sysmon for Linux EventID 1
    - Sysmon 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 IN ("java", "tomcat*", "httpd", "lighttpd", "apache2", "nginx", "node", "caddy")
      `linux_shells`
    )
    OR
    (
      Processes.parent_process_name IN ("httpd.exe", "nginx.exe", "php*.exe", "php-cgi.exe", "tomcat*.exe", "caddy.exe", "UMWorkerProcess.exe", "w3wp.exe", "ws_TomcatService.exe", "node.exe", "java.exe")
      `windows_shells`
    )
    
    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)`
    | `web_or_application_server_spawning_a_shell_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: |
    Filtering may be required on internal developer build systems or classify assets as web facing and restrict the analytic based on asset type.
references:
    - https://blog.netlab.360.com/ten-families-of-malicious-samples-are-spreading-using-the-log4j2-vulnerability-now/
    - https://gist.github.com/olafhartong/916ebc673ba066537740164f7e7e1d72
finding:
    title: An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ spawning a Linux shell, potentially indicative of exploitation.
    entity:
        field: dest
        type: system
        score: 50
threat_objects:
    - field: parent_process_name
      type: parent_process_name
    - field: process_name
      type: process_name
analytic_story:
    - BlackByte Ransomware
    - CISA AA22-257A
    - CISA AA22-264A
    - Cleo File Transfer Software
    - Data Destruction
    - Flax Typhoon
    - GhostRedirector IIS Module and Rungan Backdoor
    - HAFNIUM Group
    - Hermetic Wiper
    - Log4Shell CVE-2021-44228
    - Microsoft SharePoint Vulnerabilities
    - Microsoft WSUS CVE-2025-59287
    - PHP-CGI RCE Attack on Japanese Organizations
    - ProxyNotShell
    - ProxyShell
    - SAP NetWeaver Exploitation
    - Spring4Shell CVE-2022-22965
    - SysAid On-Prem Software CVE-2023-47246 Vulnerability
    - WS FTP Server Critical Vulnerabilities
asset_type: Endpoint
mitre_attack_id:
    - T1190
    - T1133
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint