The researchers are keen to note things about this, but also likely want to avoid giving attackers "more ideas", which I feel limits the discussion. Plus, I highly doubt these attackers don't know everything we should be discussing.
This is obviously a low hanging fruit and first PoC implementation. The fact that secure boot can "mitigate" some of this attack right now is mostly due to the attacker being lazy or deploying an unfinished product. The researchers describe this as "unless they install the attackers certificate", which is a nice way of saying that the attacker has not spent much time fishing through DKMS and abusing the keys used for this purpose.
There are a lot of systems that are affected by this type of attack because for various purposes they have to sign their own modules. The most common example of this (until extremely recently, sort of) is Nvidia.
>The fact that secure boot can "mitigate" some of this attack right now is mostly due to the attacker being lazy or deploying an unfinished product. The researchers describe this as "unless they install the attackers certificate", which is a nice way of saying that the attacker has not spent much time fishing through DKMS and abusing the keys used for this purpose.
Can you explain, or link to a source explaining this?
if you can add keys and sign things on the fly secure boot doesn't matter. it only protects you from downward payloads. if the one above the one that cares about secureboot is compromised its useless. you're confused because it's sold differently from this.
It was just a way for Microsoft's partners to limit the ease with which one can install alternative OSes. Try explaining to your mother how to disable SecureBoot to install Ubuntu. It used to be a single sentence - pop the CD in and follow the instructions, but Microsoft couldn't have that. As is always the case with Microsoft, security is never the goal unless they gain a competitive advantage or make it harder for their customers to move away in the process.
"It was just to keep people from installing something other than Windows" seems very counter-indicated by it taking ~7 years for a Windows UEFI bootkit to come out, and 13 years for one for Linux.
...and this bootkit is not able to work if Secure Boot is set up.
UEFI is also a godsend in terms of fixing a lot of the legacy BIOS crap
What makes you think that? Secure Boot prevents this rootkit from running and is the recommended mitigation:
> Bootkitty is signed by a self-signed certificate, thus is not capable of running on systems with UEFI Secure Boot enabled unless the attackers certificates have been installed.
> To keep your Linux systems safe from such threats, make sure that UEFI Secure Boot is enabled
In fairness, the blog post confusingly says this in the next bullet point:
> Bootkitty is designed to boot the Linux kernel seamlessly, whether UEFI Secure Boot is enabled or not, as it patches, in memory, the necessary functions responsible for integrity verification before GRUB is executed.
However, this would still require Rootkitty to have gained execution already, which it wouldn't be able to if Secure Boot was enabled and the malicious actor's certificates weren't installed.
and identity. most of the world now replaced your credit card and government id with apps that rely on the OS assurences to prove you're yourself with vendor keys, mandatory selfies and such.
You only need disable it until you've got that OS installed, and then you can re-enable it. All the major linux distros have supported Secure Boot for years (which I was not aware of, and will now look into setting up!)
I agree the move to UEFI added a huge new attack surface and that most UEFI implementations (notably, even the open source ones) are teeming with horrible bugs.
And yes, then linking the trust architecture for Secure Boot so deeply with UEFI means that UEFI bugs are also Secure Boot bugs.
But to say this is less secure? No way. Traditional BIOS-based MBR backdoors are like 1980s oldschool classic stuff. Most adversaries would require a good degree of development work to backdoor / root kit a PC they were given with Linux, Secure Boot, and an encrypted filesystem. With a BIOS based PC there would literally be nothing to do.
UEFI itself is way too complex, has way too much surface (I'm surprised this didn't abuse some poorly written SMI handler), and provides too little value to exist. Secure boot then goes on to treat that place as a root of trust, which is security architecture mistake, but works ok in this case. This all could be a lot better.
Nothing. This is just a proof of concept that is ridiculously easy to detect. If your attackers can drop files in your /boot or /boot/efi directory, I think you have much worse things to worry about than this.
In fact, this bootkit would be about the least thing I would worry about. Because by the time an attack can write to /boot, they can also write to /etc/init.d . And the later is not protected by "secure boot".
The researchers are keen to note things about this, but also likely want to avoid giving attackers "more ideas", which I feel limits the discussion. Plus, I highly doubt these attackers don't know everything we should be discussing.
This is obviously a low hanging fruit and first PoC implementation. The fact that secure boot can "mitigate" some of this attack right now is mostly due to the attacker being lazy or deploying an unfinished product. The researchers describe this as "unless they install the attackers certificate", which is a nice way of saying that the attacker has not spent much time fishing through DKMS and abusing the keys used for this purpose.
There are a lot of systems that are affected by this type of attack because for various purposes they have to sign their own modules. The most common example of this (until extremely recently, sort of) is Nvidia.
>The fact that secure boot can "mitigate" some of this attack right now is mostly due to the attacker being lazy or deploying an unfinished product. The researchers describe this as "unless they install the attackers certificate", which is a nice way of saying that the attacker has not spent much time fishing through DKMS and abusing the keys used for this purpose.
Can you explain, or link to a source explaining this?
if you can add keys and sign things on the fly secure boot doesn't matter. it only protects you from downward payloads. if the one above the one that cares about secureboot is compromised its useless. you're confused because it's sold differently from this.
I found this a rather interesting read, nice.
I cannot help but think the move to UEFI and Secure Boot made things less secure :(
It was just a way for Microsoft's partners to limit the ease with which one can install alternative OSes. Try explaining to your mother how to disable SecureBoot to install Ubuntu. It used to be a single sentence - pop the CD in and follow the instructions, but Microsoft couldn't have that. As is always the case with Microsoft, security is never the goal unless they gain a competitive advantage or make it harder for their customers to move away in the process.
> Try explaining to your mother how to disable SecureBoot to install Ubuntu
Good news: you don't need to!
"It was just to keep people from installing something other than Windows" seems very counter-indicated by it taking ~7 years for a Windows UEFI bootkit to come out, and 13 years for one for Linux.
...and this bootkit is not able to work if Secure Boot is set up.
UEFI is also a godsend in terms of fixing a lot of the legacy BIOS crap
> and this bootkit is not able to work if Secure Boot is set up.
wrong.
> UEFI is also a godsend in terms of fixing a lot of the legacy BIOS crap
that's like saying cutting the baby in half to end the dispute also solved the crying
What makes you think that? Secure Boot prevents this rootkit from running and is the recommended mitigation:
> Bootkitty is signed by a self-signed certificate, thus is not capable of running on systems with UEFI Secure Boot enabled unless the attackers certificates have been installed.
> To keep your Linux systems safe from such threats, make sure that UEFI Secure Boot is enabled
In fairness, the blog post confusingly says this in the next bullet point:
> Bootkitty is designed to boot the Linux kernel seamlessly, whether UEFI Secure Boot is enabled or not, as it patches, in memory, the necessary functions responsible for integrity verification before GRUB is executed.
However, this would still require Rootkitty to have gained execution already, which it wouldn't be able to if Secure Boot was enabled and the malicious actor's certificates weren't installed.
"Secure boot" is not actually meant to improve security.
It exists as a moat to make it harder to install Linux on your (Microsoft) PC.
does it also help keep drm keys safe? that's how it works on Android, they even delete the 4k keys if you root your phone.
and identity. most of the world now replaced your credit card and government id with apps that rely on the OS assurences to prove you're yourself with vendor keys, mandatory selfies and such.
What!? Last I checked even with ring0 the system didn't have access to the WideVine keys. Talk about yet another reason to just pirate everything
or buy them, but obtain a pirated version to recover what's yours when they lock you out.
The article says that Bootkitty does not work if Secure Boot is enabled. How do you figure Secure Boot made things less secure?
Gonna assume it's because you have to disable it to run your operating system of choice, unless you beg Microsoft to let you.
You only need disable it until you've got that OS installed, and then you can re-enable it. All the major linux distros have supported Secure Boot for years (which I was not aware of, and will now look into setting up!)
So that would be undesirable if true, but how would it be less secure than not having secure boot?
Of course, most/all SB BIOSes enable setting your own platform key.
What?
I agree the move to UEFI added a huge new attack surface and that most UEFI implementations (notably, even the open source ones) are teeming with horrible bugs.
And yes, then linking the trust architecture for Secure Boot so deeply with UEFI means that UEFI bugs are also Secure Boot bugs.
But to say this is less secure? No way. Traditional BIOS-based MBR backdoors are like 1980s oldschool classic stuff. Most adversaries would require a good degree of development work to backdoor / root kit a PC they were given with Linux, Secure Boot, and an encrypted filesystem. With a BIOS based PC there would literally be nothing to do.
It's more secure than not having Secure Boot.
And significantly more complicated to setup and maintain in my limited experience :|
UEFI itself is way too complex, has way too much surface (I'm surprised this didn't abuse some poorly written SMI handler), and provides too little value to exist. Secure boot then goes on to treat that place as a root of trust, which is security architecture mistake, but works ok in this case. This all could be a lot better.
I guess we need to go to back to socketed eeprom chips.
Or just in general machines that are wholly controlled by the owner.
Previously: https://news.ycombinator.com/item?id=42260346
FYI Related articles:
https://news.ycombinator.com/item?id=42262525
https://news.ycombinator.com/item?id=42264655
I think they put the Y in the wrong place; should have called it bootykit!
Not everyone is into pirates you know?
What does the discovery of the Bootkitty UEFI bootkit for Linux systems suggest about the evolving landscape of cybersecurity threats?
Nothing. This is just a proof of concept that is ridiculously easy to detect. If your attackers can drop files in your /boot or /boot/efi directory, I think you have much worse things to worry about than this.
In fact, this bootkit would be about the least thing I would worry about. Because by the time an attack can write to /boot, they can also write to /etc/init.d . And the later is not protected by "secure boot".
> Because by the time an attack can write to /boot, they can also write to /etc/init.d . And the later is not protected by "secure boot".
Bootkits are to make the infection both more difficult to detect and remove, so whether /etc/init.d is writable is pretty irrelevant.
It means "just trust us" is not and never was secure.
Trustworthy people don't ask you to trust them.
Indeed. For example, none of those CA in the built-in bundle in my browser ever asked me to trust them, that's how I know they are trustworthy.