BlackLotus malware can bypass secure boot (opens in new tab)

> At this point, we have not been able to identify, from our telemetry, the exact distribution channel used to deploy the bootkit to victims. The low number of BlackLotus samples we have been able to obtain, both from public sources and our telemetry, leads us to believe that not many threat actors have started using it yet. [0]

Right now, we don't know how it gets its way to the target.

But, we do know that it comes in the form of an installer, which then requires a system reboot to enable persistence, and then another reboot to do its actual job.

> In all subsequent boots, the self-signed UEFI bootkit is executed and deploys both its kernel driver and user-mode payload, the HTTP downloader. Together, these components are able to download and execute additional user-mode and driver components from the C&C server and protect the bootkit against removal

[0] https://www.welivesecurity.com/2023/03/01/blacklotus-uefi-bo...

> Is that something attackers can install/activate remotely through some kind of RCE, or does it need me to run an executable manually?

This piece of malware is not related to distribution, and must be executed manually (or, more likely, executed by a different malware sample serving as a loader). So you can use it in a social engineering attack, deploy it org-wide after exploiting AD, install it using some kind of RCE, etc.

The initial infection requires the ability to execute code as admin under Windows, but the writeup notes that it attempts to bypass UAC to gain that even as an unprivileged user (albeit one who is permitted to run code as admin). If you run as a user who doesn't have admin access you should be protected, even if we don't know the initial infection vector.

Didn’t Microsoft do this already? I recall a Windows update blacklisting vulnerable Linux bootloaders in UEFI.

KB5012170

So if they don’t blacklist vulnerable ntldrs, it’d be clear evidence of unequal treatment.

They won't boot immediately, but they can be trivially made to boot again by simply updating the Microsoft bootloader files on the EFI System Partition. You can even script this for PXE execution.

'BlackLotus' => 'BlackerLotus', way less desirable.

Especially because Black Lotus Labs exist and researches malware.

https://www.lumen.com/en-us/security/black-lotus-labs.html

From the official analysis [0]:

> The next feature deactivated by the installer is BitLocker Drive Encryption. The reason for this is that BitLocker can be used in a combination with Trusted Platform Module (TPM) to ensure that various boot files and configurations, including Secure Boot, haven’t been tampered with since BitLocker drive encryption was configured on the system. Considering that the installer modifies the Windows boot chain on a compromised machine, keeping BitLocker on for systems with TPM support would lead to a BitLocker recovery screen at the next bootup and would tip the victim off that the system had been compromised.

[0]: https://www.welivesecurity.com/2023/03/01/blacklotus-uefi-bo...

It doesn't trick the TPM, but as mentioned in the other comment, it does disable Bitlocker before compromising the boot chain so that won't be obvious from an end-user perspective. Remote attestation would still demonstrate that the boot chain had changed, and something like https://www.osfc.io/2022/talks/user-friendly-lightweight-tpm... would let you use your phone to determine that before logging in.

Not yet. You can still disable secure boot and install Linux. At some point in the future, it may become the same as phones. Locked bootloader/UEFI and only able to boot Windows.

they sell you the tools you need to work, each day. Just sign in!

> Oh wow, it installs its own legitimate but vunerable firmware.

No it doesn't. It's using a legitimate but vulnerable version of the windows bootloader which hasn't been added to the UEFI revocation list yet. It's not doing anything with firmware.

Downgrading UEFI firmware would be far more complicated.