Linux EFI Bootloader File Deletion

name: Linux EFI Bootloader File Deletion
id: 818a63f8-f2e1-4d1b-ac95-3a4f2ec7f113
version: 1
creation_date: '2026-07-08'
modification_date: '2026-07-08'
author: Raven Tait, Splunk
status: production
type: TTP
description: |-
    The following analytic detects file deletions in the EFI boot directory. These files are responsible for initializing the Boot Manager during system startup. Modification or replacement of these files is highly unusual in normal operations and may indicate an attempt to install a bootkit, persist malicious code at the firmware level, or otherwise tamper with the system boot process.
data_source:
    - Sysmon for Linux EventID 11
search: |-
    | tstats `security_content_summariesonly`
      count min(_time) as firstTime
            max(_time) as lastTime
    
    from datamodel=Endpoint.Filesystem where
    
    Filesystem.action="deleted"
    Filesystem.file_path="/boot/efi/EFI/BOOT/*"
    Filesystem.file_name="*.efi*"
    
    by Filesystem.file_path Filesystem.file_name Filesystem.user Filesystem.dest
       Filesystem.action Filesystem.process_guid Filesystem.process_id
    
    | `drop_dm_object_name(Filesystem)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `linux_efi_bootloader_file_deletion_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 file deletion events including the file path and user context. 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 `Filesystem` 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 system administrators or package managers may delete or replace EFI bootloader files during system updates or OS reinstallation. Filter for known maintenance windows and authorized administrative activity.
references:
    - https://www.welivesecurity.com/en/eset-research/under-cloak-uefi-secure-boot-introducing-cve-2024-7344/
    - https://www.bleepingcomputer.com/news/security/new-hybridpetya-ransomware-can-bypass-uefi-secure-boot/
finding:
    title: Linux EFI bootloader [$file_name$] deletion detected on [$dest$]
    entity:
        field: dest
        type: system
        score: 50
threat_objects:
    - field: file_name
      type: file_name
analytic_story:
    - Data Destruction
    - Linux Persistence Techniques
    - Ransomware
asset_type: Endpoint
cve:
    - CVE-2024-7344
mitre_attack_id:
    - T1542.001
    - T1542.003
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint