T1542.003 Bootkit

stealth · persistence — Linux, Windows · attack.mitre.org · JSON

MITRE detection strategy

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Sigma rules tagged attack.t1542.003

KEV CVEs mapped here

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.

KEV CVEs mapped to this technique · CTID Mappings Explorer

None. No KEV entry in the public mapping names this technique. Given that 74.7% of KEV has no mapping at all, this says more about the mapping than about the technique.

Detection strategy · ATT&CK Enterprise v19.2

DET0150 Detection Strategy for File Creation or Modification of Boot Files v1.0
AN0428 Windows
Detection of raw access to physical drives, modification of boot records (MBR/VBR), and suspicious file creation or alteration within the EFI System Partition (ESP). Correlates privileged process execution with low-level disk modification and unexpected driver or firmware interactions.

WinEventLog:Sysmon EventCode=9 → DC0054 Drive Access
WinEventLog:Sysmon EventCode=11 → DC0039 File Creation

Tunable: KnownGoodMBRHashes ESPFileWhitelist TimeWindow

AN0429 Linux
Detection of suspicious write operations to block devices, modifications of bootloader files (GRUB, initrd, vmlinuz), and unexpected changes within the EFI System Partition. Monitors privileged execution of utilities like dd, grub-install, or efibootmgr that modify boot sectors or loader entries.

auditd:SYSCALL open, write: Write operations targeting /dev/sda, /dev/nvme0n1, or EFI partition mounts → DC0061 File Modification
linux:syslog Block device write errors or unusual bootloader activity → DC0046 Drive Modification

Tunable: BootloaderHashBaseline EFIFileAllowlist AlertThresholds

Sigma rules · SigmaHQ da9bb07d64, tag `attack.t1542.003`

Potential Ransomware or Unauthorized MBR Tampering Via Bcdedit.EXE mediumtest

Author: @neu5ron · 2019-02-07 (modified 2023-02-15) · logsource: product=windows category=process_creation · c9fbe8e9-119d-40a6-9b59-dd58a5d84429

Detects potential malicious and unauthorized usage of bcdedit.exe

Techniques: T1070 T1542.003

T1542.003 Bootkit

KEV CVEs mapped to this technique · CTID Mappings Explorer

Detection strategy · ATT&CK Enterprise v19.2

Sigma rules · SigmaHQ da9bb07d64, tag attack.t1542.003

Sigma rules · SigmaHQ da9bb07d64, tag `attack.t1542.003`