Adversaries may modify system firmware to persist on systems.The BIOS (Basic Input/Output System) and The Unified Extensible Firmware Interface (UEFI) or Extensible Firmware Interface (EFI) are examples of system firmware that operate as the software interface between the operating system and hardware of a computer.(Citation: Wikipedia BIOS)(Citation: Wikipedia UEFI)(Citation: About UEFI)
System firmware like BIOS and (U)EFI underly the functionality of a computer and may be modified by an adversary to perform or assist in malicious activity. Capabilities exist to overwrite the system firmware, which may give sophisticated adversaries a means to install malicious firmware updates as a means of persistence on a system that may be difficult to detect.
View in MITRE ATT&CK®| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| intel-ptt | Intel Platform Trust Technology | Win 11, Secure Boot | T1542.001 | System Firmware |
Comments
Windows Secure Boot leverages Intel PTT (TPM) to safeguard settings stored in UEFI, while Intel Boot Guard prevents unauthorized modifications to UEFI firmware. It verifies the signatures of the UEFI firmware, bootloader, and boot drivers before loading the operating system.
When the PC starts, the firmware checks the signature of each piece of boot software, including Unified Extensible Firmware Interface (UEFI) firmware drivers (also known as Option ROMs), Extensible Firmware Interface (EFI) applications, and the operating system. If the signatures are valid, the PC boots, and the firmware gives control to the operating system. Rollback protection also prevents the system from rolling back to older versions of firmware.
Secure Boot employs Intel PTT (TPM) to thwart attacks that attempt to alter the signature policy at the boot level in real-time or modify components involved in the boot process before the boot process. Intel Boot Guard ensures the integrity of the boot-level code before it is executed on the processor, preventing the system from proceeding with malicious boot code.
Secure Boot is able to address threats pre-os that change the signature of the loaded boot component.
System Guard Secure Launch uses a technology called Dynamic Root of Trust Measurement (DRTM). It leverages Intel PTT (TPM) and TXT to provide secure methods to boot a system and verify the integrity of the operating system and loading mechanisms. System Guard Secure Launch ensures that the system can freely boot into untrusted code initially, but shortly after launches the system into a trusted state by taking control of all CPUs and forcing them down a well-known and measured code path. This has the benefit of allowing untrusted early code to boot the system but then being able to securely transition into a trusted and measured state. The ability to transition in real-time to a secure state justified the score of significant for this feature and its corresponding protection (E.g., bootkit, rootkit, firmware corruption, etc.).
References
|