Linux High Frequency Of File Deletion In Boot Folder

name: Linux High Frequency Of File Deletion In Boot Folder
id: e27fbc5d-0445-4c4a-bc39-87f060d5c602
version: 12
creation_date: '2022-04-12'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: TTP
description: The following analytic detects a high frequency of file deletions in the /boot/ folder on Linux systems. It leverages filesystem event logs to identify when 200 or more files are deleted within an hour by the same process. This behavior is significant as it may indicate the presence of wiper malware, such as Industroyer2, which targets critical system directories. If confirmed malicious, this activity could lead to system instability or failure, hindering the boot process and potentially causing a complete system compromise.
data_source:
    - Sysmon for Linux EventID 11
search: |-
    | tstats `security_content_summariesonly` values(Filesystem.file_access_time) as file_access_time values(Filesystem.file_create_time) as file_create_time values(Filesystem.file_hash) as file_hash values(Filesystem.file_modify_time) as file_modify_time values(Filesystem.file_name) as file_name values(Filesystem.file_path) as file_path  values(Filesystem.file_acl) as file_acl values(Filesystem.file_size) as file_size values(Filesystem.process_id) as process_id values(Filesystem.user) as user values(Filesystem.vendor_product) as vendor_product dc(Filesystem.file_path) as numOfDelFilePath count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem
      WHERE Filesystem.action=deleted Filesystem.file_path = "/boot/*"
      BY _time span=1h Filesystem.dest
         Filesystem.process_guid Filesystem.action
    | `drop_dm_object_name(Filesystem)`
    | where  numOfDelFilePath >= 200
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `linux_high_frequency_of_file_deletion_in_boot_folder_filter`
how_to_implement: To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you can use the Add-on for Linux Sysmon from Splunkbase.
known_false_positives: linux package installer/uninstaller may cause this event. Please update you filter macro to remove false positives.
references:
    - https://www.welivesecurity.com/2022/04/12/industroyer2-industroyer-reloaded/
    - https://cert.gov.ua/article/39518
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"
finding:
    title: Multiple files detection in /boot/ folder on $dest$ by process GUID -  $process_guid$
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - Data Destruction
    - Industroyer2
    - AcidPour
asset_type: Endpoint
mitre_attack_id:
    - T1070.004
    - T1485
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/T1485/rm_boot_dir/sysmon_linux.log
          source: Syslog:Linux-Sysmon/Operational
          sourcetype: sysmon:linux
      test_type: unit