4 ms·

"An authentication bypass is bad, but a full compromise would have been much worse." Given the authentication bypass essentially leads to full compromise, wher

"An authentication bypass is bad, but a full compromise would have been much worse." Given the authentication bypass essentially leads to full compromise, where's the difference, here?

dom0 10y ago
The ME itself is not compromised. Arbitrary code execution on the ME would mean total control of the host, i.e. privileges above any software you can run on a computer.
- kogepathic 10y ago
  > would mean total control of the host, i.e. privileges above any software you can run on a computer. You don't need arbitrary code execution, the ME already has privileges above any software you can run on the computer. The ME operates in ring -2 mode [0], whereas the OS kernel has at most ring 0 privileges. With the built-in ME functionality you can: reboot the host, change BIOS settings, re-install the OS, update BIOS (boot FreeDOS & run the vendor utility). Couple this with a vendor vulnerability such as not signing and verifying a BIOS before flashing, and you can easily use the ME to flash a BIOS with malicious components to the computer. So, yes, it's not as bad as using the ME to read arbitrary memory regions while the host is on, but the default ME functionality for remote management is still enough for a malicious actor to cause a lot of harm. [0] https://en.wikipedia.org/wiki/System_Management_Mode https://en.wikipedia.org/wiki/System_Management_Mode
  - pritambaral 10y ago
    > ring -2 mode ME runs below the SMM. So ring -3 or lower.
    - qb45 10y ago
      ME is a separate processor, not a "ring" on the x86. All this talk about "privilege level above normal software" and "ring -7" just muddies the water. It simply is a physically separate core running its own software which has access to all RAM and all PCIe devices and can program the Intel NIC to silently redirect selected packets away from the x86 cores to itself.
- tyingq 10y ago
  AMT offers basically IPMI though. Boot a recovery image over the net, mount the local drive, and edit away.
qb45 10y ago
The difference is, you are no longer limited to functionality normally provided by AMT. Maybe AMT doesn't offer the ability to download arbitrary memory locations from the running OS and applications, with remote code execution on the ME you could do that. You could modify code running on the CPU on-the-fly and make it read files from disk to memory for downloading too - again, I don't think AMT can read disks, especially when the OS is running and using them concurrently.
- lima 10y ago
  Exactly, AMT is essentially a remote console without any sort of direct access to the running system. You'd have to reboot the system with a remotely recovery media in order to compromise it.
- tyingq 10y ago
  You can boot a recovery image though, and edit files on the installed OS that way.
  - qb45 10y ago
    It just isn't quite as stealthy if you have to power up the box when it's supposed to be off. I mean, not everybody runs Windows 10 and is used to his machine having a free will of its own ;)

"An authentication bypass is bad, but a full compromise would have been much worse." Given the authentication bypass essentially leads to full compromise, where's the difference, here?

dom0 10y ago

The ME itself is not compromised. Arbitrary code execution on the ME would mean total control of the host, i.e. privileges above any software you can run on a computer.

kogepathic 10y ago
> would mean total control of the host, i.e. privileges above any software you can run on a computer. You don't need arbitrary code execution, the ME already has privileges above any software you can run on the computer. The ME operates in ring -2 mode [0], whereas the OS kernel has at most ring 0 privileges. With the built-in ME functionality you can: reboot the host, change BIOS settings, re-install the OS, update BIOS (boot FreeDOS & run the vendor utility). Couple this with a vendor vulnerability such as not signing and verifying a BIOS before flashing, and you can easily use the ME to flash a BIOS with malicious components to the computer. So, yes, it's not as bad as using the ME to read arbitrary memory regions while the host is on, but the default ME functionality for remote management is still enough for a malicious actor to cause a lot of harm. [0] https://en.wikipedia.org/wiki/System_Management_Mode https://en.wikipedia.org/wiki/System_Management_Mode
- pritambaral 10y ago
  > ring -2 mode ME runs below the SMM. So ring -3 or lower.
  - qb45 10y ago
    ME is a separate processor, not a "ring" on the x86. All this talk about "privilege level above normal software" and "ring -7" just muddies the water. It simply is a physically separate core running its own software which has access to all RAM and all PCIe devices and can program the Intel NIC to silently redirect selected packets away from the x86 cores to itself.
tyingq 10y ago
AMT offers basically IPMI though. Boot a recovery image over the net, mount the local drive, and edit away.

qb45 10y ago

The difference is, you are no longer limited to functionality normally provided by AMT. Maybe AMT doesn't offer the ability to download arbitrary memory locations from the running OS and applications, with remote code execution on the ME you could do that. You could modify code running on the CPU on-the-fly and make it read files from disk to memory for downloading too - again, I don't think AMT can read disks, especially when the OS is running and using them concurrently.

lima 10y ago
Exactly, AMT is essentially a remote console without any sort of direct access to the running system. You'd have to reboot the system with a remotely recovery media in order to compromise it.
tyingq 10y ago
You can boot a recovery image though, and edit files on the installed OS that way.
- qb45 10y ago
  It just isn't quite as stealthy if you have to power up the box when it's supposed to be off. I mean, not everybody runs Windows 10 and is used to his machine having a free will of its own ;)