Linux Binary Executed from Shared Memory Directory

SPLUNK detection rule by Raven Tait, Splunk · Apache-2.0

The following analytic identifies the execution of a binary by root from Linux shared memory directories (/dev/shm/ and /run/shm/). Threat actors place executables in these directories to persist on high-uptime servers as system backdoors. Both /dev/shm and /run/shm are tmpfs-backed directories that exist only in virtual memory with no persistent storage, making them attractive for staging fileless or semi-fileless malware while avoiding disk forensics.

name: Linux Binary Executed from Shared Memory Directory
id: 2e954190-d547-447c-94d7-d8acac97873b
version: 1
creation_date: '2026-07-08'
modification_date: '2026-07-08'
author: Raven Tait, Splunk
status: production
type: Anomaly
description: |-
    The following analytic identifies the execution of a binary by root from Linux shared memory directories (/dev/shm/ and /run/shm/). Threat actors place executables in these directories to persist on high-uptime servers as system backdoors. Both /dev/shm and /run/shm are tmpfs-backed directories that exist only in virtual memory with no persistent storage, making them attractive for staging fileless or semi-fileless malware while avoiding disk forensics.
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_path IN (
        "/dev/shm/*",
        "/run/shm/*"
    )
    Processes.user=root

    by Processes.process Processes.process_path Processes.process_name Processes.user
       Processes.user_id Processes.process_hash Processes.parent_process_name
       Processes.parent_process_path Processes.parent_process Processes.parent_process_guid
       Processes.parent_process_id Processes.process_guid Processes.process_id
       Processes.vendor_product Processes.action Processes.dest
       Processes.process_current_directory Processes.process_integrity_level
       Processes.original_file_name

    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `linux_binary_executed_from_shared_memory_directory_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: |-
    Legitimate applications may use shared memory directories for temporary file storage or inter-process communication. Verify any flagged activity against known software behavior and filter accordingly.
references:
    - https://linuxsecurity.com/features/fileless-malware-on-linux
    - https://twitter.com/GossiTheDog/status/1522964028284411907
    - https://github.com/elastic/detection-rules/blob/main/rules/linux/execution_process_started_in_shared_memory_directory.toml
drilldown_searches:
    - earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
      name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search  user = "$user$" dest = "$dest$"'
    - name: View risk events for the last 7 days for - "$user$" and "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") | 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: Linux binary executed from shared memory directory [$process$] - activity observed on [$dest$].
        - field: user
          type: user
          score: 20
          message: Linux binary executed from shared memory directory [$process$] - activity observed on [$dest$].
threat_objects:
    - field: process_name
      type: process_name
    - field: process
      type: process
analytic_story:
    - Linux Post-Exploitation
    - Linux Persistence Techniques
    - Linux Privilege Escalation
    - Compromised Linux Host
asset_type: Endpoint
mitre_attack_id:
    - T1059
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      test_type: unit
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059/linux_binary_executed_from_shared_memory_directory/snapattack_linux.log
          source: Syslog:Linux-Sysmon/Operational
          sourcetype: sysmon:linux

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

592e21cc-32c6-4cbe-8998-84a0a7f9eb9b

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Executable code, not a declarative rule

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Format & documentation suggestions

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