Friday, January 13th 2017

Intel's Skylake and Kaby Lake-based Systems Vulnerable to USB Exploit

At this year's CCC hacker congress, researchers from Positive Technologies have released information, which documents vulnerabilities in Intel's Skylake and Kaby Lake series processors' handling of USB 3.0-based debugging - which could be used to attack, corrupt, and even subvert a user's system.

This vulnerability allows attackers to bypass typical security mechanisms - both at the hardware and at the OS level - by using a new debugging interface, which could allow them to install malware and/or rewrite the system's firmware and BIOS. The exploit is currently undetectable using existing security tools, and according to the researchers, this mechanism can be used on a hacked system regardless of the OS installed.
Before Skylake, low-level machine debugging was available through a special device that connected to the motherboard's debugging port (ITP-XDP). It was not easily accessible, though - not every board carries the relevant connections; also the hardware and software as expensive and difficult to acquire - so there was not much concern regarding the scale and impact of the attacks (if you recall, typical risk measurement considers both the severity of an exploit's effect as well as the probability of that exploit being explored). That changed when Skylake came out, which introduced the Direct Connect Interface (DCI) that provides access to the JTAG debugging interface through a specific standard USB 3.0 port on the motherboard - a technology which is much more ubiquitous and easily accessible.

There are no hardware or software tricks needed for an attacker to exploit this, all that is required is that the DCI interface is enabled. On many systems, DCI is enabled by default. On those that are not, there are several ways to enable it. Once DCI is activated, it works like any kernel debugger: the CPU can be paused, all memory and register contents can be read and written, without the operating system ever noticing that it was paused in the first place. The researchers have already reported this vulnerability to Intel, though at this time there is no fix available. The fact that any individual with malicious intent needs to have physical access to the machine and its USB 3.0 ports makes this exploit a little more difficult to accomplish, but it would seem that workplaces or servers are particularly vulnerable. One minor caveat is that only a single, board-specific, USB 3.0 port can be used for debugging, so an attacker would have to try out all of them, or know the right one for that hardware configuration.

Motherboard vendors could provide a BIOS update, which disables DCI debugging and locks it down, so that any software running after the BIOS can not re-enable it.

The researchers have also uploaded a video where they explain the process in more detail. Watch the video right here:

Sources: YouTube, HotHardware, Overclock3D
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41 Comments on Intel's Skylake and Kaby Lake-based Systems Vulnerable to USB Exploit

#26
ZeDestructor
silentbogoOk, here's a comment from one of the more paranoid members of TPU, e.g. me:
1) This exploit heavily relies on debugging interface being enabled. On 99.9% of all skylake systems(even laptops and tablets) it is not.
2) In order to enable the debugging interface you have to be able to update BIOS and ME firmware. So, it's not going to be as simple as sticking something in USB port (some boards even have ME locked via jumper)
3) The method itself, even if successful and meets all preconditions, is so unpractical, that you may as well ignore it. No Evil NSA Agent, or Crazy Russian Hacker is going to break into your house, update your BIOS, stick something weird into your USB port, just so he can monitor and log all of your naughty porn history.

It may be interesting from an academic perspective, but it will never become a new "rubber ducky", because it requires unrestricted access to the target system (which kind of defeats the purpose).

BTW, I haven't seen anyone blaming MS for Kernel Mode Debugging, or Google for ADB. Those present more imminent danger and are network-friendly.
For me and you, no. But for high-value targets on the other hand (political dissidents, journalists in various places, security researchers researching certain targets, people with access to very cutting-endge IP for example), it's a perfectly valid attack point. Once you are a target, you should worry. For the rest of us, we fly by being too many to target.
Posted on Reply
#27
Easy Rhino
Linux Advocate
The hacker who discovered this obviously has some insight into the machine code so this smells like an inside job. Regardless, all software is hack-able. If you are afraid someone will compromise your system using a USB stick you best lock up your PC in a safe before leaving the house.
Posted on Reply
#28
silentbogo
ZeDestructorFor me and you, no. But for high-value targets on the other hand (political dissidents, journalists in various places, security researchers researching certain targets, people with access to very cutting-endge IP for example), it's a perfectly valid attack point. Once you are a target, you should worry. For the rest of us, we fly by being too many to target.
You've probably skipped the "unpractical" part. If you have access to UEFI firmware, it will be easy to exploit existing UEFI bugs, rather than doing this circle-jerk in order to do the same thing.

It's like, if you are a hypothetical evil NSA agent, and you need to surveil some anti-political rebel journalist, you are going to dress up as a phone company employee and install a tiny ultrasonic speaker into user's PC, alongside a trojan which uses webcam mic to record all conversations, then you implant an ultrasonic mic into his landline phone and transmit the recorded conversations via Dail-up while no one is home. By the time you are done installing all of this, the Journalist will probably accept you as a family member, or at least an accidental roommate, and tell you his secrets anyway.
Posted on Reply
#29
ZeDestructor
silentbogoYou've probably skipped the "unpractical" part. If you have access to UEFI firmware, it will be easy to exploit existing UEFI bugs, rather than doing this circle-jerk in order to do the same thing.

It's like, if you are a hypothetical evil NSA agent, and you need to surveil some anti-political rebel journalist, you are going to dress up as a phone company employee and install a tiny ultrasonic speaker into user's PC, alongside a trojan which uses webcam mic to record all conversations, then you implant an ultrasonic mic into his landline phone and transmit the recorded conversations via Dail-up while no one is home. By the time you are done installing all of this, the Journalist will probably accept you as a family member, or at least an accidental roommate, and tell you his secrets anyway.
Intercepting the machine in the mail or customs is safer and easier. And for all the bit's you've listed, a pro can do easily in under an hour if they're fully prepared.
Posted on Reply
#30
thesmokingman
Woot, now this is some progress. Who cares about IPC when it's even faster to hack now!
Posted on Reply
#31
Brusfantomet
thesmokingmanWoot, now this is some progress. Who cares about IPC when it's even faster to hack now!
We could start measuring Incursions Per Clock in stead.
Posted on Reply
#32
DRDNA
Steven BThat isn't a U SKU CPU, so it's not affected.
Yeah but I also have this one coming today and looks like it will be vulnerable.
ASUS Premium High Performance 15.6" FHD Laptop(Intel Core i7-5500U, 8GB RAM, 1TB HDD, DVD,Windows 10- Black)

looks like I'm gonna need my tinfoil again! lol
Posted on Reply
#34
mcraygsx
hapkimanNot a huge deal.
Not a big deal for trolls or people living under rock like yourself. But for IT Industry, it sure is.
Posted on Reply
#35
lexluthermiester
Easy RhinoThe hacker who discovered this obviously has some insight into the machine code so this smells like an inside job. Regardless, all software is hack-able. If you are afraid someone will compromise your system using a USB stick you best lock up your PC in a safe before leaving the house.
It should be noted however, that this hacking method can NOT be used to bypass full disc encryption, if the system is off when the attempt is made. I am referring to Truecrypt, VeraCrypt and the like. Bitlocker does not count as it requires part of the OS to remain unencrypted.
Posted on Reply
#37
lexluthermiester
silentbogoOk, here's a comment from one of the more paranoid members of TPU, e.g. me:
1) This exploit heavily relies on debugging interface being enabled. On 99.9% of all skylake systems(even laptops and tablets) it is not.
2) In order to enable the debugging interface you have to be able to update BIOS and ME firmware. So, it's not going to be as simple as sticking something in USB port (some boards even have ME locked via jumper)
3) The method itself, even if successful and meets all preconditions, is so unpractical, that you may as well ignore it. No Evil NSA Agent, or Crazy Russian Hacker is going to break into your house, update your BIOS, stick something weird into your USB port, just so he can monitor and log all of your naughty porn history.

It may be interesting from an academic perspective, but it will never become a new "rubber ducky", because it requires unrestricted access to the target system (which kind of defeats the purpose).

BTW, I haven't seen anyone blaming MS for Kernel Mode Debugging, or Google for ADB. Those present more imminent danger and are network-friendly.
Hey be nice, Crazy Russian Hacker is cool! [ www.youtube.com/user/CrazyRussianHacker ]

And FYI, ADB is not as network friendly as you think. Trust me on that one!
Posted on Reply
#38
silentbogo
lexluthermiesterHey be nice, Crazy Russian Hacker is cool! [ www.youtube.com/user/CrazyRussianHacker ]

And FYI, ADB is not as network friendly as you think. Trust me on that one!
Just like JTAG over USB is not as easy to work with as advertised (or flashing UEFI firmware with homemade tools for that matter).

ah....that CrazyRussianHacker... then we are all doomed, because "Safety is numbeg one pgiogity"! :roll:
Posted on Reply
#39
lexluthermiester
silentbogoJust like JTAG over USB is not as easy to work with as advertised (or flashing UEFI firmware with homemade tools for that matter).

ah....that CrazyRussianHacker... then we are all doomed, because "Safety is numbeg one pgiogity"! :roll:
Right? Been watching his video's for a while and his english is getting better as time does on. But we're getting off-topic..
Posted on Reply
#40
silentbogo
I only know about this dude, because he keeps popping up in Youtube suggested videos, no matter how hard I try to avoid him.
Almost like RED21 with his DIY cheeseburger.:banghead:
Posted on Reply
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