7 ms·

BlackLotus malware can bypass secure boot

147 points by mrcsno 4y ago

aspyct 4y ago
How is that malware deployed to a machine? Is that something attackers can install/activate remotely through some kind of RCE, or does it need me to run an executable manually? In other words, is it still enough to be careful with social engineering, or are we more screwed than that?
- shakna 4y ago
  > 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-bootkit-myth-confirmed/ https://www.welivesecurity.com/2023/03/01/blacklotus-uefi-bo...
  - aspyct 4y ago
    Thanks :)
- mjg59 4y ago
  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.
  - 323 4y ago
    > If you run as a user who doesn't have admin access you should be protected, That's not very reassuring. Privilege escalation on Windows is a well studied subject: https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/Methodology%20and%20Resources/Windows%20-%20Privilege%20Escalation.md https://github.com/swisskyrepo/PayloadsAllTheThings/blob/mas...
- msm_ 4y ago
  > 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.
georgyo 4y ago
By passing secure boot is pretty bad, but the article doesn't mention anything about the TPM. Even if you trick uefi to execute this exploit, surely the TPM will have different measurements and not release the encryption key. The article says it can run on windows 11, which does imply it also tricks the TPM but I would love confirmation.
- bayindirh 4y ago
  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-bootkit-myth-confirmed/ https://www.welivesecurity.com/2023/03/01/blacklotus-uefi-bo...
  - moremetadata 4y ago
    > [0]: https://www.welivesecurity.com/2023/03/01/blacklotus-uefi-bo https://www.welivesecurity.com/2023/03/01/blacklotus-uefi-bo... So how do you remove it?
    - mavhc 4y ago
      Bitlocker? If you're Admin in Windows you can just unencrypt your drive
    - jeroenhd 4y ago
      Disable-Bitlocker should do the trick: https://learn.microsoft.com/en-us/powershell/module/bitlocker/disable-bitlocker?view=windowsserver2022-ps https://learn.microsoft.com/en-us/powershell/module/bitlocke... Obviously requires admin permissions on a running host, but if you're injecting into the bootloader you're already admin (or you can get it easily).
AaronFriel 4y ago
Duplicate? https://news.ycombinator.com/item?id=34985793 https://news.ycombinator.com/item?id=34985793
SCHiM 4y ago
It's quite a painful split that Microsoft is in given their commitment to backwards compatibility. The exploit can still be deployed by malicious actors on patched devices because they can bring old vulnerable signed bootloaders. And roll back any applied patches. These old signed bootloaders could technically by revoked, but if Microsoft does that then all old backups, possibly going back years, will no longer boot when restored. I can imagine there's many hundreds of thousands of backups that would then be silently broken. Imagine you find that out when you restore after a disaster...
- formerly_proven 4y ago
  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.
  - wkat4242 4y ago
    I bet they are a lot more inclined to blacklist old Linux bootloaders than Windows ones, precisely because of this backup restore thing that the OP mentioned. They'll get the support burden if nothing else.
- aaronmdjones 4y ago
  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.
holdenc137 4y ago
Perhaps we could ever so slightly dissuade malware actors by assigning less desirable names. E.g. instead of 'BlackLotus' => 'LameEffort-12'
- croes 4y ago
  Especially because Black Lotus Labs exist and researches malware. https://www.lumen.com/en-us/security/black-lotus-labs.html https://www.lumen.com/en-us/security/black-lotus-labs.html
- gpderetta 4y ago
  'BlackLotus' => 'BlackerLotus', way less desirable.
  - wkat4242 4y ago
    Or BlackOrifice as a pun on the old rootkit. Cybersecurity has become big business since then though, and as such a much more carefully PRed rubber tile community, sadly.
jhoelzel 4y ago
You mean the thousands of computers that have to be thrown away to use windows 11 are using it for profit and not security?? -shocked Pikachu face-
- M95D 4y ago
  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.
  - jhoelzel 4y ago
    While true, this is going to be a tough topic to bring up at the clients office. So far I am contemplating building a throne from them.
  - hnthrowaway0315 4y ago
    Can you please elaborate what does it mean to be the same as phones? I guess you meant the sandbox env?
    - jhoelzel 4y ago
      I think what he was saying is that, by locking down the bootloader, we could see devices that are locked to windows or apple forever. Just like iphones are
r9295 4y ago
Very interesting, thanks for sharing
2OEH8eoCRo0 4y ago
I'm glad we are locking down our machines and relinquishing control to Microsoft for singing so that we can still be owned.
- mistrial9 4y ago
  they sell you the tools you need to work, each day. Just sign in!
  - Tangurena2 4y ago
    In one of my grumpier moments, I complained that we were "just digital sharecroppers." Looking back, I'm also grateful for the Microsoft ecosystem that has given me about 25 years of employment as a developer.
stavros 4y ago
Oh wow, it installs its own legitimate but vunerable firmware. I don't know why this tickles me so much, but it does.
- resoluteteeth 4y ago
  > 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.

147 points by mrcsno 4y ago

How is that malware deployed to a machine? Is that something attackers can install/activate remotely through some kind of RCE, or does it need me to run an executable manually? In other words, is it still enough to be careful with social engineering, or are we more screwed than that?

shakna 4y ago
> 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-bootkit-myth-confirmed/ https://www.welivesecurity.com/2023/03/01/blacklotus-uefi-bo...
- aspyct 4y ago
  Thanks :)
mjg59 4y ago
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.
- 323 4y ago
  > If you run as a user who doesn't have admin access you should be protected, That's not very reassuring. Privilege escalation on Windows is a well studied subject: https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/Methodology%20and%20Resources/Windows%20-%20Privilege%20Escalation.md https://github.com/swisskyrepo/PayloadsAllTheThings/blob/mas...
msm_ 4y ago
> 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.

georgyo 4y ago

By passing secure boot is pretty bad, but the article doesn't mention anything about the TPM. Even if you trick uefi to execute this exploit, surely the TPM will have different measurements and not release the encryption key. The article says it can run on windows 11, which does imply it also tricks the TPM but I would love confirmation.

bayindirh 4y ago
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-bootkit-myth-confirmed/ https://www.welivesecurity.com/2023/03/01/blacklotus-uefi-bo...
- moremetadata 4y ago
  > [0]: https://www.welivesecurity.com/2023/03/01/blacklotus-uefi-bo https://www.welivesecurity.com/2023/03/01/blacklotus-uefi-bo... So how do you remove it?
  - mavhc 4y ago
    Bitlocker? If you're Admin in Windows you can just unencrypt your drive
  - jeroenhd 4y ago
    Disable-Bitlocker should do the trick: https://learn.microsoft.com/en-us/powershell/module/bitlocker/disable-bitlocker?view=windowsserver2022-ps https://learn.microsoft.com/en-us/powershell/module/bitlocke... Obviously requires admin permissions on a running host, but if you're injecting into the bootloader you're already admin (or you can get it easily).

AaronFriel 4y ago

Duplicate? https://news.ycombinator.com/item?id=34985793 https://news.ycombinator.com/item?id=34985793

SCHiM 4y ago

It's quite a painful split that Microsoft is in given their commitment to backwards compatibility. The exploit can still be deployed by malicious actors on patched devices because they can bring old vulnerable signed bootloaders. And roll back any applied patches. These old signed bootloaders could technically by revoked, but if Microsoft does that then all old backups, possibly going back years, will no longer boot when restored. I can imagine there's many hundreds of thousands of backups that would then be silently broken. Imagine you find that out when you restore after a disaster...

formerly_proven 4y ago
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.
- wkat4242 4y ago
  I bet they are a lot more inclined to blacklist old Linux bootloaders than Windows ones, precisely because of this backup restore thing that the OP mentioned. They'll get the support burden if nothing else.
aaronmdjones 4y ago
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.

holdenc137 4y ago

Perhaps we could ever so slightly dissuade malware actors by assigning less desirable names. E.g. instead of 'BlackLotus' => 'LameEffort-12'

croes 4y ago
Especially because Black Lotus Labs exist and researches malware. https://www.lumen.com/en-us/security/black-lotus-labs.html https://www.lumen.com/en-us/security/black-lotus-labs.html
gpderetta 4y ago
'BlackLotus' => 'BlackerLotus', way less desirable.
- wkat4242 4y ago
  Or BlackOrifice as a pun on the old rootkit. Cybersecurity has become big business since then though, and as such a much more carefully PRed rubber tile community, sadly.

jhoelzel 4y ago

You mean the thousands of computers that have to be thrown away to use windows 11 are using it for profit and not security?? -shocked Pikachu face-

M95D 4y ago
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.
- jhoelzel 4y ago
  While true, this is going to be a tough topic to bring up at the clients office. So far I am contemplating building a throne from them.
- hnthrowaway0315 4y ago
  Can you please elaborate what does it mean to be the same as phones? I guess you meant the sandbox env?
  - jhoelzel 4y ago
    I think what he was saying is that, by locking down the bootloader, we could see devices that are locked to windows or apple forever. Just like iphones are

r9295 4y ago

Very interesting, thanks for sharing

2OEH8eoCRo0 4y ago

I'm glad we are locking down our machines and relinquishing control to Microsoft for singing so that we can still be owned.

mistrial9 4y ago
they sell you the tools you need to work, each day. Just sign in!
- Tangurena2 4y ago
  In one of my grumpier moments, I complained that we were "just digital sharecroppers." Looking back, I'm also grateful for the Microsoft ecosystem that has given me about 25 years of employment as a developer.

stavros 4y ago

Oh wow, it installs its own legitimate but vunerable firmware. I don't know why this tickles me so much, but it does.

resoluteteeth 4y ago
> 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.