Windows EFI Bootloader File Modification
Detects where a process writes to critical EFI bootloader files (bootmgfw.efi or bootx64.efi) within the \EFI\Boot\ directory. These files are responsible for initializing the Windows Boot Manager during system…
Description
Detects where a process writes to critical EFI bootloader files (bootmgfw.efi or bootx64.efi) within the \EFI\Boot\ directory. These files are responsible for initializing the Windows 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.
Detection logic
Detection requirements
- Platform
- LinuxWindows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
- Log source category
- sysmon_eventid_11
Known benign triggers
- Legitimate system updates or authorized IT maintenance may modify EFI bootloader files. Review changes against approved maintenance windows and tools.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| www.bleepingcomputer.com/news/security/new-hybridpetya-ransomware-can-bypass-uefi-secure-boot/ | 4 |
| www.welivesecurity.com/en/eset-research/under-cloak-uefi-secure-boot-introducing-cve-2024-7344/ | 4 |
From the source
- At source
- Open at source
- Upstream identifier
- 28e1dbcd-9fd2-4de0-a637-f2b30db5dbb9
- Tagged by the source as
- Windows BootKitsEndpointendpointSplunk CloudSplunk EnterpriseSplunk Enterprise Securityendpoint
Licence
- Published under
- Apache License 2.0Read the licence
- Attribution
- Required
- Obtained under
- Apache-2.0Read the origin licence
Authorship
- Written by
- Published
- Aug 26, 2026
- Version
- 1