Linux Possible Append Command To Profile Config File

SPLUNK detection rule by Teoderick Contreras, Splunk · Apache-2.0

The following analytic detects suspicious command-lines that modify user profile files to automatically execute scripts or executables upon system reboot. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions involving profile files like ~/.bashrc and /etc/profile. This activity is significant as it indicates potential persistence mechanisms used by adversaries to maintain access to compromised hosts. If confirmed malicious, this could allow attackers to execute arbitrary code upon reboot, leading to persistent control over the system and potential further exploitation.

name: Linux Possible Append Command To Profile Config File
id: 9c94732a-61af-11ec-91e3-acde48001122
version: 12
creation_date: '2022-01-11'
modification_date: '2026-08-12'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: |-
    The following analytic detects suspicious command-lines that modify user profile files to automatically execute scripts or executables upon system reboot.
    It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions involving profile files like ~/.bashrc and /etc/profile.
    This activity is significant as it indicates potential persistence mechanisms used by adversaries to maintain access to compromised hosts.
    If confirmed malicious, this could allow attackers to execute arbitrary code upon reboot, leading to persistent control over the system and potential further exploitation.
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 = "*echo*"
    (
        Processes.process IN ("*/home/*", "*~/*", "*/etc/*")
        Processes.process IN (
            "*/.bash_login*",
            "*/.bash_logout*",
            "*/.bash_profile*",
            "*/.bashrc*",
            "*/.profile*",
            "*/profile*"
        )
        OR
        (
            Processes.process_current_directory = "/home/*"
            Processes.process IN (
                "*.bash_login*",
                "*.bash_logout*",
                "*.bash_profile*",
                "*.bashrc*",
                "*.profile*",
                "* profile*"
            )
        )
    )

    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_current_directory 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_append_command_to_profile_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://unix.stackexchange.com/questions/129143/what-is-the-purpose-of-bashrc-and-how-does-it-work
    - https://attack.mitre.org/techniques/T1546/004/
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: The [$process_name$] process is attempting to modify Shell Profile files via the Command Line [$process$] on [$dest$]
threat_objects:
    - field: process
      type: process
analytic_story:
    - Linux Privilege Escalation
    - Linux Persistence Techniques
asset_type: Endpoint
mitre_attack_id:
    - T1546.004
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/T1546.004/linux_init_profile/sysmon_linux.log
          source: Syslog:Linux-Sysmon/Operational
          sourcetype: sysmon:linux
      test_type: unit

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

7c233c81-8eb1-4008-82db-5480361480ba

Propose edits, view related rules, and engage with the community through comments.

Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

[[ reason ]]

What does this mean?

Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

[[ reason ]]

What do these messages mean?

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

Community Discussion