Unkillable UEFI Malware Bypassing Secure Boot Enabled By Unpatchable Windows Flaw

'Researchers have announced a major cybersecurity find -- the world's first-known instance of real-world malware that can hijack a computer's boot process even when Secure Boot and other advanced protections are enabled and running on fully updated versions of Windows. From a report: Dubbed BlackLotus, the malware is what's known as a UEFI bootkit. These sophisticated pieces of malware hijack the UEFI -- short for Unified Extensible Firmware Interface -- the low-level and complex chain of firmware responsible for booting up virtually every modern computer. As the mechanism that bridges a PC's device firmware with its operating system, the UEFI is an OS in its own right. It's located in an SPI-connected flash storage chip soldered onto the computer motherboard, making it difficult to inspect or patch. Because the UEFI is the first thing to run when a computer is turned on, it influences the OS, security apps, and all other software that follows. These traits make the UEFI the perfect place to run malware. When successful, UEFI bootkits disable OS security mechanisms and ensure that a computer remains infected with stealthy malware that runs at the kernel mode or user mode, even after the operating system is reinstalled or a hard drive is replaced. As appealing as it is to threat actors to install nearly invisible and unremovable malware that has kernel-level access, there are a few formidable hurdles standing in their way. One is the requirement that they first hack the device and gain administrator system rights, either by exploiting one or more vulnerabilities in the OS or apps or by tricking a user into installing trojanized software. Only after this high bar is cleared can the threat actor attempt an installation of the bootkit. The second thing standing in the way of UEFI attacks is UEFI Secure Boot, an industry-wide standard that uses cryptographic signatures to ensure that each piece of software used during startup is trusted by a computer's manufacturer. Secure Boot is designed to create a chain of trust that will prevent attackers from replacing the intended bootup firmware with malicious firmware. If a single firmware link in that chain isn't recognized, Secure Boot will prevent the device from starting.' -- source: https://it.slashdot.org/story/23/03/06/1854200 Cheers, Peter -- Peter Reutemann Dept. of Computer Science University of Waikato, Hamilton, NZ Mobile +64 22 190 2375 https://www.cs.waikato.ac.nz/~fracpete/ http://www.data-mining.co.nz/

On Tue, 7 Mar 2023 09:53:23 +1300, Peter Reutemann quoted:
'Researchers have announced a major cybersecurity find -- the world's first-known instance of real-world malware that can hijack a computer's boot process even when Secure Boot and other advanced protections are enabled and running on fully updated versions of Windows.'
From the article <https://arstechnica.com/information-technology/2023/03/unkillable-uefi-malware-bypassing-secure-boot-enabled-by-unpatchable-windows-flaw/>:
Despite Microsoft releasing new patched software, the vulnerable signed binaries have yet to be added to the UEFI revocation list that flags boot files that should no longer be trusted. Microsoft has not explained the reason, but it likely has to do with hundreds of vulnerable bootloaders that remain in use today. If those signed binaries are revoked, millions of devices will no longer work. As a result, fully updated devices remain vulnerable because attackers can simply replace patched software with the older, vulnerable software. What’s the point of having a revocation list, if you cannot actually revoke anything?

On Tue, 7 Mar 2023 10:14:10 +1300, I wrote:
What’s the point of having a revocation list, if you cannot actually revoke anything?
Further to this, yet another serious Secure Boot bug has been uncovered <https://arstechnica.com/information-technology/2023/05/microsoft-patches-secure-boot-flaw-but-wont-enable-fix-by-default-until-early-2024/>. This is one is so bad that fixing it will render useless all existing Windows boot media -- this includes install media (standard and custom), full OS backups, network boot drives, Windows PE boot media -- everything. For this reason, Microsoft is saying it will take a full year to completely roll out the fix. This is to give users time to adapt to the breaking changes. What’s the bet even one year won’t be enough?
participants (2)
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Lawrence D'Oliveiro
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Peter Reutemann