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taviso's profile
Tavis Ormandy
Tavis Ormandy
Tavis Ormandy
Verified account
@taviso

Tweets

Tavis OrmandyVerified account

@taviso

Vulnerability researcher at Google. This is a personal stream, opinions expressed are mine.

California
taviso.decsystem.org
Joined April 2008

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    1. Brendan Dolan-Gavitt‏ @moyix Feb 24
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      Did not realize Hyper-V vulnerabilities were worth up to $250,000 (!). I guess because of Azure?

      6 replies 13 retweets 54 likes
    2. Matt Miller‏ @epakskape Feb 24
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      Replying to @moyix

      Hyper-V security is important for Azure, the various Windows features built on top of Hyper-V (WDAG, WDAC, VBS, etc), and of course for anyone using Hyper-V for isolating untrusted code :)

      1 reply 0 retweets 14 likes
    3. Gabriele‏ @intercomputable Feb 25
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      Replying to @epakskape @moyix

      http://lists.dragonflybsd.org/pipermail/users/2017-August/335428.html …

      1 reply 0 retweets 1 like
    4. Matt Miller‏ @epakskape Feb 25
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      Replying to @intercomputable @moyix

      Suffice it to say that I disagree with this post 🙂 My opinion is that the virtualization boundary is the strongest software security boundary that currently exists

      1 reply 0 retweets 5 likes
    5. Dmitry Vyukov‏ @dvyukov Feb 26
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      Replying to @epakskape @moyix

      API surface it's pretty large: insn emulation, hypercalls, MSRs, device emul, page tables, etc. Large API surface conflicts with security. But it depends on concrete impl and testing/fuzzing story. "I booted stock kernel in qemu, so it's all good to go" or something more.

      1 reply 0 retweets 10 likes
    6. Matt Miller‏ @epakskape Feb 26
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      Replying to @dvyukov @moyix

      Good topic for debate with >280 chars :) In the general case, I think the attack surface of OS-based process isolation is strictly greater than virtualization-based isolation (side channels in particular), but I agree it depends on the specific design & impl.

      1 reply 0 retweets 6 likes
      Tavis Ormandy‏Verified account @taviso Feb 26
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      Replying to @epakskape @dvyukov @moyix

      It depends for sure, I think I'd be dubious of any argument for virtualization being a stronger boundary than seccomp strict, for example... any ipc out of the sandbox would be identical, likely the weak point :)

      9:00 AM - 26 Feb 2020
      • 1 Retweet
      • 9 Likes
      • Michael DP halvarflake InsanityBit ⏢Ben Gardiner I̗̘̦͝n͇͇͙v̮̫ok̲̫̙͈i̖͙̭̹̠̞n̡̻̮̣̺g̲͈͙̭ Brendan Dolan-Gavitt Matt Miller Ben Gras
      3 replies 1 retweet 9 likes
        1. New conversation
        2. halvarflake‏ @halvarflake Feb 26
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          Replying to @taviso @epakskape and

          I *think* I am in the seccomp-strict camp here (for men corruption for sure). For side channels I would have to think really hard.

          2 replies 0 retweets 6 likes
        3. Matt Miller‏ @epakskape Feb 26
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          Replying to @halvarflake @taviso and

          I think seccomp-strict and VM isolation with a minimal VMM (e.g. Windows Hypervisor Platform) approach similar levels of attack surface for mem corruption For side channels, consider the monolithic kernel address space (w/ multi-tenant data) & etc vs.https://techcommunity.microsoft.com/t5/virtualization/hyper-v-hyperclear-mitigation-for-l1-terminal-fault/ba-p/382429 …

          1 reply 0 retweets 4 likes
        4. 8 more replies
        1. New conversation
        2. Dmitry Vyukov‏ @dvyukov Feb 26
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          Replying to @taviso @epakskape @moyix

          Other things that come to mind: gVisor and NaCl. Say if you do NaCl with strict seccomp policy (basically, computations only)... I would probably trust it more than full VM virtualization.

          1 reply 0 retweets 9 likes
        3. Matt Miller‏ @epakskape Feb 26
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          Replying to @dvyukov @taviso @moyix

          Yep, agreed, in specific scenarios (e.g. seccomp strict profile + limited ipc) the attack surface for process isolation could be made much smaller. But even in this scenario, I think conventional OS kernel design is more difficult to defend against side channels

          1 reply 0 retweets 5 likes
        4. 4 more replies
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        2. Dan Kaminsky‏Verified account @dakami Feb 26
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          Replying to @taviso @epakskape and

          I’m coming around to WASM. A little embarrassed I used to brag about how few syscalls virt needed. Oh, vmexit is a syscall too. Not that virt isn’t also interesting!

          1 reply 0 retweets 4 likes
        3. Dan Kaminsky‏Verified account @dakami Feb 26
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          Replying to @dakami @taviso and

          It always depends what you’re piping *to*.

          0 replies 0 retweets 2 likes
        4. End of conversation

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