Sub-technique of T1542 Pre-OS Boot.View on attack.mitre.org
Adversaries may use bootkits to persist on systems. A bootkit is a malware variant that modifies the boot sectors of a hard drive, allowing malicious code to execute before a computer's operating system has loaded. Bootkits reside at a layer below the operating system and may make it difficult to perform full remediation unless an organization suspects one was used and can act accordingly.
In BIOS systems, a bootkit may modify the Master Boot Record (MBR) and/or Volume Boot Record (VBR). The MBR is the section of disk that is first loaded after completing hardware initialization by the BIOS. It is the location of the boot loader. An adversary who has raw access to the boot drive may overwrite this area, diverting execution during startup from the normal boot loader to adversary code.
The MBR passes control of the boot process to the VBR. Similar to the case of MBR, an adversary who has raw access to the boot drive may overwrite the VBR to divert execution during startup to adversary code.
In UEFI (Unified Extensible Firmware Interface) systems, a bootkit may instead create or modify files in the EFI system partition (ESP). The ESP is a partition on data storage used by devices containing UEFI that allows the system to boot the OS and other utilities used by the system. An adversary can use the newly created or patched files in the ESP to run malicious kernel code.
Rules on DetectionCode tagged with T1542.003.
| Rule | Level | Log source |
|---|---|---|
| Potential Ransomware or Unauthorized MBR Tampering Via Bcdedit.EXE | medium | windows / process_creation |
| Rule | Type | Risk | Data source |
|---|---|---|---|
| Linux EFI Bootloader File Deletion | TTP | NULL | Sysmon for Linux EventID 11 |
| Windows EFI Bootloader File Modification | TTP | NULL | Sysmon EventID 11 |
| Windows WinLogon with Public Network Connection | Hunting | NULL | Sysmon EventID 1 AND Sysmon EventID 3 |
None recorded.
| Used by | Procedure example |
|---|---|
| GroupAPT28 | APT28 has deployed a bootkit along with Downdelph to ensure its persistence on the victim. The bootkit shares code with some variants of BlackEnergy. |
| GroupAPT41 | APT41 deployed Master Boot Record bootkits on Windows systems to hide their malware and maintain persistence on victim systems. |
| GroupLazarus Group | Lazarus Group malware WhiskeyAlfa-Three modifies sector 0 of the Master Boot Record (MBR) to ensure that the malware will persist even if a victim machine shuts down. |
| Used by | Procedure example |
|---|---|
| MalwareBOOTRASH | BOOTRASH is a Volume Boot Record (VBR) bootkit that uses the VBR to maintain persistence. |
| MalwareCarberp | Carberp has installed a bootkit on the system to maintain persistence. |
| MalwareFinFisher | Some FinFisher variants incorporate an MBR rootkit. |
| MalwareROCKBOOT | ROCKBOOT is a Master Boot Record (MBR) bootkit that uses the MBR to establish persistence. |
| MalwareTrickBot | TrickBot can implant malicious code into a compromised device's firmware. |
| MalwareWhisperGate | WhisperGate overwrites the MBR with a bootloader component that performs destructive wiping operations on hard drives and displays a fake ransom note when the host boots. |
Data from MITRE ATT&CK® (Enterprise). ATT&CK® is a registered trademark of The MITRE Corporation.
