linux_possible_access_to_credential_files.yml

name: Linux Possible Access To Credential Files
id: 16107e0e-71fc-11ec-b862-acde48001122
version: 1
date: '2022-01-10'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: This analytic is to detect a possible attempt to dump or access the content
  of /etc/passwd and /etc/shadow to enable offline credential cracking. "etc/passwd"
  store user information within linux OS while "etc/shadow" contain the user passwords
  hash. Adversaries and threat actors may attempt to access this to gain persistence
  and/or privilege escalation. This anomaly detection can be a good indicator of possible
  credential dumping technique but it might catch some normal administrator automation
  scripts or during credential auditing. In this scenario filter is needed.
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.process_name IN("cat",
  "nano*","vim*", "vi*")  AND Processes.process IN("*/etc/shadow*", "*/etc/passwd*")
  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_possible_access_to_credential_files_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: Administrator or network operator can execute this command.
  Please update the filter macros to remove false positives.
references:
- https://askubuntu.com/questions/445361/what-is-difference-between-etc-shadow-and-etc-passwd
- https://attack.mitre.org/techniques/T1003/008/
tags:
  analytic_story:
  - Linux Privilege Escalation
  - Linux Persistence Techniques
  asset_type: Endpoint
  confidence: 50
  impact: 50
  message: A commandline $process$ executed on $dest$
  mitre_attack_id:
  - T1003.008
  - T1003
  observable:
  - name: dest
    type: Hostname
    role:
    - Victim
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - Processes.dest
  - Processes.user
  - Processes.parent_process_name
  - Processes.process_name
  - Processes.process
  - Processes.process_id
  - Processes.parent_process_id
  risk_score: 25
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1003.008/copy_file_stdoutpipe/sysmon_linux.log
    source: Syslog:Linux-Sysmon/Operational
    sourcetype: sysmon_linux