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    Alex Ionescu

    alex-ionescu.com · Personal blog · on HN since 2012

    Alex Ionescu, a Windows internals researcher and ReactOS developer, writes about Windows kernel architecture, security features and low-level instrumentation.

    Visit blogHN submissions
    Systems & PerformanceSecurity
    What HN says

    HN commenters cite him as an authority on Windows internals, linking his posts on process protection, memory behavior and changes in Windows 10.

    Stats for nerds
    18HN people shared it
    17linked in comments
    436story points
    Aug 2023last shared
    2014people per year2023

    Top posts on HN

    1. 1
      Windows Internals, 7th Edition
      1 person · 174 points · first shared 2017 · 24 comments on HN
    2. 2
      How Windows 10 Rewrites OS Architecture: Battle of SKM and IUM [pdf]
      2 people · 59 points · first shared 2015 · 26 comments on HN
    3. 3
      Writing a Hyper-V Bridge for Fuzzing: Hypercalls and MDLs
      1 person · 52 points · first shared 2019 · 1 comments on HN
    4. 4
      Bringing Call Gates Back
      2 people · 48 points · first shared 2017 · 9 comments on HN
    5. 5
      How Control Flow Guard Caused Windows 8.1 Address Space and Behavior Changes
      2 people · 42 points · first shared 2015 · 3 comments on HN
    6. 6
      Lego's packing process isn't perfect
      1 person · 32 points · first shared 2012 · 13 comments on HN
    7. 7
      A Codeless PE Binary File That Runs
      1 person · 10 points · first shared 2014 · Discussion on HN
    8. 8
      Owning the Object File Format, the Compiler Toolchain, and the Operating System
      3 people · 5 points · first shared 2016 · 1 comments on HN
    9. 9
      Dynamic Tracing in Windows 10
      3 people · 4 points · first shared 2018 · Discussion on HN
    10. 10
      Intel SGX Enclave Support in Windows 10 Fall Update [pdf]
      2 people · 4 points · first shared 2015 · 1 comments on HN

    What HN people wrote when they linked it

    • MarkSweepJan 2019

      The article confuses address space and memory reservations as you note. It again makes the confusion when it suggests the virtual size column in Process Explorer is a reflection of the address space[1]. It also suggests that working set, private bytes, and committed memory are the same thing[2]. The article does not even live up to its click-baity title: Task Manager's default memory column of "private working set" is a decent measure of how much memory a process is uniquely using and task manager has the ability to add all the other measures of memory usage that the article mentions.

      For a better explanation of virtual memory in Windows, I recommend Mark Russinovich's article[3]. His tool VMMap[4] is useful for visualizing the memory usage of an individual process.

      [1]: The reserved memory is really large for 64-bit processes that use Control Flow Gaurd: http://www.alex-ionescu.com/?p=246

      [2]: Task Manager and Process Explorer add to the confusion by calling the same memory different things (Process Explorer's "private bytes" number is the same as Task Manager's "commit size" number on Windows 10 1809).

      [3]: https://blogs.technet.microsoft.com/markrussinovich/2008/11/17/pushing-the-limits-of-windows-virtual-memory/

      [4]: https://docs.microsoft.com/en-us/sysinternals/downloads/vmmap

    • JdeBPAug 2016

      It's not "coming out of Black Hat". It's coming from Alex Ionescu, via his GitHub account. You have an identifiable person with a known reputation here, not some unidentifiable person hiding behind a pseudonym.

      The problems that you have are quite different ones:

      * Demonstrating that the Alex Ionescu of http://www.alex-ionescu.com/ and of https://microsoftpressstore.com/authors/bio.aspx?a=07cda0ad-d0ed-4ccc-a1c9-c25f54fa8c74 is the Alex Ionescu of https://twitter.com/aionescu/status/710477975288827904 and of https://github.com/ionescu007 . It's difficult to show a connection in that direction. The Alex Ionescu of https://alexionescu.net/#contact lets people connect the dots — a different set of dots, mind you.

      * Knowing that https://github.com/ is the real GitHub. If this is a problem for you, then you have more serious and urgent problems than viewing a PDF document. (-:

    • staticassertionAug 2021

      This is a big capability. Right now it's quite difficult (requiring pinning together a few pieces of technology) to protect one process from another, especially if the other process is root. This isn't enough to get quite there, but it's a good start.

      Windows has been working on similar tech via Protected Processes[0], notably used for both LSASS and their new eBPF verifier. That's been a tricky technology to get right but I think it's interesting.

      > Andy Lutomirski repeatedly opposed making uncached mappings available, objecting to the performance cost and more;

      Interesting. I'll want to read more into this.

      My guess is that for the next 5 years there will be endless ways to leak these secrets and maybe, if we're lucky, things will improve over that time.

      [0] https://www.alex-ionescu.com/?p=97

    • transputeJan 2016

      Note that Intel signs [1] software which runs in SGX enclaves. Windows 10 uses [2][3] SGX.

      Intel got a pretty long patent on SGX a few years ago.
      In it, they say that the launch enclave will only issue
      launch tokens after ensuring that the enclave's author has
      a business agreement with Intel. The patent also states
      that they expect enclaves to be useful for DRM, so I'm
      guessing they want to insert themselves into the
      entertainment content distribution systems and collect
      some royalties.

      [1] https://jbeekman.nl/blog/2015/10/intel-has-full-control-over-sgx/

      [2] http://www.alex-ionescu.com/Enclave%20Support%20In%20Windows%2010%20Fall%20Update.pdf

      [3] https://software.intel.com/en-us/sgx-sdk/documentation

    • wolfgkeJan 2017

      > Apple is headed down the path that the old Microsoft was headed.

      Exactly.

      > Which they, Microsoft, have ironically backed away from.

      Are you really sure that Microsoft backed away from this path? Just google about "Intel SGX (Software Guard Extensions)" and inform yourself how Windows 10 uses/plans to use them. To help you a little bit for researching on this topic, here are two references:

      > https://sec.ch9.ms/slides/winHEC/03_WindowsSecurity.pdf

      > http://www.alex-ionescu.com/Enclave%20Support%20In%20Windows%2010%20Fall%20Update.pdf

    • krackersAug 2023

      I assume this one for heaven's gate: https://www.alex-ionescu.com/closing-heavens-gate/

      But that's very windows specific, I think the general term is jumping between long mode and protected mode?

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