S3E19: "Byte Sudo Sys Jail Privilege"

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Recorded (UTC) Aired (UTC) Editor
2018-11-08 03:29:35 2018-11-18 15:26:13 "Edita"
Format SHA256 GPG Audio File
MP3 d7602916a23e766ef557b689600c6f5e200c9100d7c4e24953ff9932c34f8bfd click click
OGG 3be1b22e527e9ddc5004e97c79bd5103ede0b8717241b61e432a4587d332689a click click

Just Jthan and myself again. We talk about ways of separating privileges on a GNU/Linux (and some UNIX/BSD) systems based on a listener writing in. Jthan saw a furry on Halloween.

I also spend a weirdly large amount of time talking about Nagasaki and Hiroshima.



Starts at 20m58s.

I was drinking chai (again) and a Porterhouse’s An Brain Blásta again (same as S3E18). Jthan was drinking Michter’s American Whiskey. (Paden wasn’t with us again.)

  • We reply to this comment.
    • One can configure the wheel group (or any specific group, really; tradition just dictates it’s “wheel”) to facilitate checks for su (and found in BSDs and other unices as well).
      • Please see the Errata! We fucked this up, just s/sudo/su/g in this discussion topic. It’s been a while since I used the wheel group. :)
    • We’ll, at some point in the future, do an entire episode on sudo. :) Until then, though, I highly recommend watching this talk.
      • I still say you don’t need augeas to manage sudo users – just add/remove files, one per user, under /etc/sudoers.d/. :P
    • Another way of segregating software can be via virtual environments, which we dicuss the pros/cons of at (heated) length, in S3E3.
    • You technically can use containers for this, but I wouldn’t. The entire reason the topic came up is because of one of the many weaknesses in containers we were discussing. ;)
      • We’ll probably be talking about Vagrant in the future, so you can manage full VMs as if they were containers.
    • Chroots are tried-and-true for separating out software, but you have to be careful. There are a lot of ways of escaping chroots, and even scripted ways. Basically, make sure nobody has shell in a chroot and never EVER gets root user access inside that chroot, and you should be okay. Though at that point, it does sort of render chroots useless from a segregation functionality.
    • BSD jails are indeed just as easily escaped, and don’t let any fanboy tell you differently. The difference is they also can run different bincompats. A rough analog of this would be, for instance, a 32-bit chroot on a 64-bit (non-multilib) host, and how it has to be entered via the linux32/setarch utility. Alternatively, a more direct analog would be LXC (Linux containers) – though it’s Linux-only. You cannot run a BSD container on a Linux host (but why would you ever need to?) — a VM is still the recommended course anyways.
    • We do also mention briefly the WSL.
    • The most guaranteed sort of privilege separation is probably going to be hardware separation.
    • We talk about SELinux (and grsecurity/PAX) in S1E6 and AppArmor in S2E6.

Sysbadministration Award

In this segment, we highlight system administration mistakes. Think of them as the IT equivalent of the Darwin Awards. (50m10s)

There was a public 0day in VirtualBox. The Baddie goes to both Oracle for the severity/ease of escalation of the vulnerability, and to the researcher for not following an ethical disclosure policy (as far as I know).


  • Yes, Jthan, sneezing is indeed quite traumatic to the human body. It’s not surprising; the air that leaves your head from the sudden contractions is traveling around 100mph (that’s about 161kph, or 45m/s).
  • I think I mentioned Toyko when talking about bombing… They benefited economically and developmentally from the renovation, but the bombs themselves were dropped on Hiroshima and Nagasaki (duh).
  • I did indeed do this while typing up the notes, as I predicted during the episode:
13:10:11 < r00t^2> sysbot: r00t^2 is also an unzen bitch
13:10:12 <@sysbot> r00t^2: yeah, let me get RIGHT fucking on that for you, fucker.
13:10:16 < r00t^2> jthan: ^ 4 u
  • Jthan talks about wheel in the context of sudo rather than su, and I forget to correct him because seriously, who the fuck uses su anymore when you can use sudo?
    • He also wasn’t using ‘requited’ correctly.
    • And I say sudo -u, I actually meant sudo -i. Talking about the terminal vs. sitting in front of it is a lot different and harder. :(
    • I confirmed – SUSE (OpenSUSE, at the very least) does not use wheel group membership. It doesn’t even have a wheel group upon initial install.
  • RIP, Foresight Linux.


Music Credits
Track Title Artist Link Copyright/License
Intro Breathing Out Mid-Air Machine click CC-BY-SA 4.0
Outro Fake Protest Song(feat. Ema Grace) Ryoma Maeda click CC-BY 4.0
(All music is royalty-free, properly licensed for use, used under fair use, or public domain.)



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