name: Linux Java Spawning Shell
id: 7b09db8a-5c20-11ec-9945-acde48001122
version: 1
date: '2023-04-14'
author: Michael Haag, Splunk
status: production
type: TTP
description: The following analytic identifies the process name of Java, Apache, or
  Tomcat spawning a Linux shell. This is potentially indicative of exploitation of
  the Java application and may be related to current event CVE-2021-44228 (Log4Shell).
  The shells included in the macro are "sh", "ksh", "zsh", "bash", "dash", "rbash",
  "fish", "csh', "tcsh', "ion", "eshell". Upon triage, review parallel processes and
  command-line arguments to determine legitimacy.
data_source:
- Sysmon Event ID 1
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
  as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name=java
  OR Processes.parent_process_name=apache OR Processes.parent_process_name=tomcat
  `linux_shells` by Processes.dest Processes.user Processes.parent_process_name Processes.process_name
  Processes.process Processes.process_id Processes.parent_process_id | `drop_dm_object_name(Processes)`
  | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `linux_java_spawning_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
tags:
  analytic_story:
  - Data Destruction
  - Spring4Shell CVE-2022-22965
  - Hermetic Wiper
  - Log4Shell CVE-2021-44228
  asset_type: Endpoint
  confidence: 50
  cve:
  - CVE-2021-44228
  impact: 80
  message: An instance of $parent_process_name$ spawning $process_name$ was identified
    on endpoint $dest$ spawning a Linux shell, potentially indicative of exploitation.
  mitre_attack_id:
  - T1190
  - T1133
  observable:
  - name: dest
    type: Hostname
    role:
    - Victim
  - name: parent_process_name
    type: Process
    role:
    - Parent Process
  - name: process_name
    type: Process
    role:
    - Child Process
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - Processes.dest
  - Processes.user
  - Processes.parent_process_name
  - Processes.parent_process
  - Processes.original_file_name
  - Processes.process_name
  - Processes.process
  - Processes.process_id
  - Processes.parent_process_path
  - Processes.process_path
  - Processes.parent_process_id
  risk_score: 40
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1190/java/java_spawn_shell_nix.log
    source: Syslog:Linux-Sysmon/Operational
    sourcetype: sysmon_linux