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Thunderbolt Rootkit Vector

Posted by Soulskill on from the like-USB-but-better dept.

New submitter Holi sends this news from PC World: Attackers can infect MacBook computers with highly persistent boot rootkits by connecting malicious devices to them over the Thunderbolt interface. The attack, dubbed Thunderstrike, installs malicious code in a MacBook's boot ROM (read-only memory), which is stored in a chip on the motherboard. It was devised by a security researcher named Trammell Hudson based on a two-year old vulnerability and will be demonstrated next week at the 31st Chaos Communication Congress in Hamburg.

11 of 163 comments (clear)

  1. uh - by design? by Nerrd · · Score: 4, Insightful

    It shouldn't surprise anybody that a malicious PCI-E card can access a system.

    1. Re:uh - by design? by darkain · · Score: 4, Insightful

      DisplayPort monitor pre-infected with malware?

    2. Re:uh - by design? by jeffb+(2.718) · · Score: 4, Insightful

      Thunderbolt is more like USB to the user - it's a thing you use to connect untrusted devices to your system.

      Thunderbolt is more like PCIe to the system -- it's a thing you use to connect trusted devices to your system. In fact, it is PCIe, along with DisplayPort.

      The one mitigating factor is that, while there are Thunderbolt devices out there, users are less likely to find one lying in the company parking lot and decide "durr, let me plug this into my work computer and see what's on it". That seems to be a pretty effective delivery method for hostile USB devices.

    3. Re:uh - by design? by Anonymous Coward · · Score: 2, Insightful

      It doesn't even have to be a whole monitor. An innocent looking cable would suffice. Apple's own cables already contain microcontrollers.

    4. Re:uh - by design? by AmiMoJo · · Score: 3, Insightful

      USB 3.0's DMA is not the same as Thunderbolt's. With USB the host controller configures itself with limited DMA access to a RAM buffer, and then the USB device can only access that buffer by setting up transfers within the USB spec. In fact it can't even specify the address within the buffer or anything like that, the controller handles it all. It's closer to a NIC that supports DMA - it doesn't mean that any device on your network has full access to your computer's RAM.

      Thunderbolt is rather different, because the devices are basically PCI-E cards with a Thunderbolt transceiver bolted on. As such they can do anything that a PCI-E card can do, including accessing all RAM. PC Card devices have the same issue, and so does Firewire. It's a serious issue and tools that exploit it have been available for a while, both open source and commercial. For example: http://www.breaknenter.org/pro...

      The BadUSB attack relies on either exploiting bugs in the USB driver or emulating something like a keyboard and typing commands into a terminal. It's bad, but not nearly as bad as having complete, unfettered access to RAM by design. For example, a locked computer or server that isn't logged in locally is unlikely to be affected by BadUSB because it can't know the login details, but with Thunderbolt you have total access.

      --
      const int one = 65536; (Silvermoon, Texture.cs)
      SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
    5. Re:uh - by design? by fustakrakich · · Score: 2, Insightful

      EPROM! Otherwise the story makes no sense... If you can write to ROM (more than once), clearly it's not ROM.

      --
      “He’s not deformed, he’s just drunk!”
  2. Hasn't this been known? by maccodemonkey · · Score: 5, Insightful

    Firewire, USB 3.0, and Thunderbolt all have DMA, which means any device hooked to a host can pretty much do anything they want to the host, no matter what the host hardware or OS is. I didn't think this sort of thing was still news?

    1. Re:Hasn't this been known? by maccodemonkey · · Score: 4, Insightful

      Well, now I'm reading specs on USB 3.0 controllers. Ugh. There's a lot on mapping a bus address to a memory address for DMA, but nothing addressing the security implications of doing so, or what devices are allowed to do, just broad hints like the buffer has to exist in a DMA-able part of memory without saying if that's a security implication or a hardware implication.

      It would be nice to see a follow up article on if/how USB 3.0 protects against these things, because I'm not a kernel USB developer sort of guy, so while I know DMA is there, I'm not feeling like I'd be able to dissect these implementation specs.

  3. Putting unprotected flash in computers was stupid by Anonymous Coward · · Score: 2, Insightful

    Almost as stupid as making PCI-E part of an external bus. The BIOS write protect jumper of old was the right idea.

  4. Attacker does *not* need physical access ... by perpenso · · Score: 5, Insightful

    An attacker with physical access to the target is usually a bad thing (tm),

    The attacker does not need physical access. All the attacker needs to do is sell hacked thunderbolt cables on ebay or alibaba.

  5. Re:In other news... by fuzzyfuzzyfungus · · Score: 4, Insightful

    I'm frankly surprised to hear that Apple still manufactures a device that will boot after you tinker with its boot ROM. The notion that a device that is, for most purposes, right on the PCIe bus can scribble all over the place isn't exactly a shock; but it doesn't seem much like Apple to build hardware that would still boot if the cryptographic signatures didn't check out.