When it launched, Windows 11 confused a lot of people over its requirement that your PC
have a security chip called a TPM or a trusted platform module.
But now, Microsoft wants to transition away from the TPM and instead implement its own
security chip inside of upcoming CPUs.
Microsoft calls this new chip, Pluton.
But why is this a big deal? It helps to first understand the limitations of the current TPM system.
TPMs contain the keys needed to encrypt and decrypt data on your devices, and they can
either come in the form of a separate chip that sits on your motherboard, you can actually
buy them for your desktop, or as a firmware TPM, which consists of code that hangs out
either on your system's chipset or on the CPU itself.
Most CPU platforms manufactured these days have some form of firmware TPM built in, hence
the reason Microsoft says you're probably okay to upgrade to Windows 11 if you have
a recently built PC. But TPM is far from perfect.
It's certainly better than nothing, but it turns out it's not particularly hard to defeat if an attacker knows what they're doing.
A key weakness can be found in the connection between the TPM and the BIOS.
You can actually connect a sniffing device to the pins on the TPM chip and obtain the
key you're looking for in a matter of minutes. Of course, you need physical access to the target PC in order to pull off an attack like
this, but seeing as how the TPM was meant to help protect computers, even if a miscreant
had physical access, it's a pretty big liability.
But say you're running a firmware TPM implementation, well, these can still have their own vulnerabilities.
The well-publicized Spectre and Meltdown exploits have shown that attackers can grab data directly
off a CPU. Even if that data is subject to enhanced security, it can still be obtained, such as in the Platypus
attack that bypasses Intel's software guard extensions, or SGX.
This feature is supposed to create a secured area of the processor, but not only does Platypus
defeat it, physical access isn't even required to attack the secured area.
Pluton is, in theory, I just love that name, supposed to go a long way towards solving
these problems. Pluton doesn't use a separate chip at all, instead it's baked directly onto the CPU die,
so there isn't a risk of snatching data off a communication bus like you can with a discrete
TPM module. But how is Pluton different from firmware TPM, since those already run directly on the
CPU? So a firmware TPM runs its code on the same main CPU cores that run your other programs,
so a successful attack on something else the CPU is running could compromise the firmware
TPM. Pluton, on the other hand, works by adding additional hardware that's on the CPU die,
but is separate from the main processing cores, making it more difficult to attack, even if
the bad guy has physical access to the computer. Additionally, Microsoft is going to be responsible for issuing firmware updates for Pluton rather
than motherboard manufacturers, who typically release new firmware versions much less frequently.
This should help keep computers safer from new and evolving threats.
The first PCs with Pluton built in should start hitting store shelves in mid-2022, but
Pluton actually isn't even brand new. The chips have actually been used since 2013 in Xbox consoles to make it harder to play
pirated titles, which actually brings us to a concern some users have about Pluton.
Some fear that Microsoft could use Pluton to lock down PCs and exert too much control
over what consumers can and cannot run on their own machines.
We do know that CPUs with Pluton will work and run on Linux, but if you want Pluton's
extra features, the specific Linux distro you're using would need to be able to support
for those. So the only time will tell if these concerns about Pluton are warranted, but I'm sure we
can all agree that we trust Microsoft, right?
They made this stuff.