Linux Possible Access Or Modification Of sshd Config File

name: Linux Possible Access Or Modification Of sshd Config File
id: 7a85eb24-72da-11ec-ac76-acde48001122
version: 11
creation_date: '2022-01-12'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic detects suspicious access or modification of the sshd_config file on Linux systems. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions involving processes like "cat," "nano," "vim," and "vi" accessing the sshd_config file. This activity is significant because unauthorized changes to sshd_config can allow threat actors to redirect port connections or use unauthorized keys, potentially compromising the system. If confirmed malicious, this could lead to unauthorized access, privilege escalation, or persistent backdoor access, posing a severe security risk.
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/ssh/sshd_config")
      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_possible_access_or_modification_of_sshd_config_file_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 use this commandline for automation purposes. Please update the filter macros to remove false positives.
references:
    - https://www.hackingarticles.in/ssh-penetration-testing-port-22/
    - https://attack.mitre.org/techniques/T1098/004/
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 ("$dest$") | 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: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: a commandline $process$ executed on $dest$
analytic_story:
    - Linux Privilege Escalation
    - Linux Persistence Techniques
    - Linux Living Off The Land
asset_type: Endpoint
mitre_attack_id:
    - T1098.004
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1098.004/ssh_authorized_keys/sysmon_linux.log
          source: Syslog:Linux-Sysmon/Operational
          sourcetype: sysmon:linux
      test_type: unit