What things do I need to worry about? I'm about to make the switch from Windows to Linux.
Is it general 'dont run things you don't trust'? keep things updated? Use good passwords?(do I need to change a setting to prevent brute forcing?)
Am I missing anything?
Nowadays, the web browser is used as a platform to run programs on and so it has a lot of access to weird things (multiple monitors, local filesystem, ...) so one has to be careful what you enable there--since you probably run a lot of Javascript written by shady people you don't know.
The Linux desktop security model has user accounts, and then files have permissions for those users (yeah, there are also user groups, whatever). That means if you have a misbehaving (or malicious) program, it can read stuff in your home directory since that's owned by the same user account--so it can read your saved passwords, delete all your photos, figure out your banking info--but hey, at least it can't remove your printer (since for the latter you need to use the root user account :P) /s .
There are mitigations against that and the easiest (and crappiest) one is containerization: just run each program in an isolated virtual-machine-like-thing and they can't access other program's data (i.e. the rest of YOUR data) in the first place.
Then there's SELinux which flips this entire thing on its head. By default, nobody can do anything (that's the first very good decision!). If a process wants to do things, there has to be a policy installed that mentions that specific thing to be allowed and when. Otherwise no go. This way of working is much safer, BUT someone has to maintain those policies! And it must not be the program's author since he could just add whatever line he wants to have to the policy--and that's obviously bad. So who does it? Usually the Linux distribution's maintainer. Or, more commonly, nobody--so there's no policy for your favorite program and so it won't work.
which can totally happen on a VM, but not a VM in-and-of-itself
https://en.wikipedia.org/wiki/OS-level_virtualization
Good to know about it. Especially once you meet decades-experienced folks (mainframe guys), they rather use the word "virtualization" in its broader sense, yet they understand the difference between containers and virtual machines.
https://www.ibm.com/cloud/blog/containers-vs-vms#:~:text=Con....
Carnegie Melon University chimes in as well:
https://insights.sei.cmu.edu/blog/virtualization-via-contain...
Amazon AWS:
is container virtualization
Well, if you rent containers, you get containers. If you rent bare-metal machines, you get bare metal machines. So I don't see how this assertion makes any sense.
The CMU article skims around the names but call containers "virtual runtime environment" instead of straight "virtualization". But by that definition everything in any modern computer is "virtualized" because it runs over Virtual Memory.
If you use a mainstream distro like Fedora or Ubuntu, its default configuration should be safe enough to use like Windows. Just remember that there isn't really any antivirus or Microsoft Defender to save you if you really mess up. I do offline backups of important work on all my devices, for this reason partially.
Can you explain this? What are the exploits?
Is it the equivalent of running a .exe or .jar on windows, but with an extra layer of protection? (Or am I trying to shove my windows ideas into linux?)
Traditional desktop Linux allows different apps to more-or-less freely communicate with each other (called the x11 protocol). This works really well for old apps (and admittedly not too bad for new ones) but is very slow and exposes a lot of bugs. On top of this, you have potential exploits in your filesystem from loosely permissioning important settings and identity files. So, the attack surface for a traditional Linux distro is relatively large.
> Is it the equivalent of running a .exe or .jar on windows, but with an extra layer of protection?
Kinda! Linux software is distributed as packages, which contains a binary (the exe/jar portion), a dependency manifest and whatever static content it needs. A sandbox like Flatpak will take those packages and put it into a sandbox, to prevent hostile interprocess communication and filesystem exploits.
None of these mitigations are perfect per-se (nor are they on Mac/Windows), so use them wisely if you intend to use them at all. I have used a non-sandboxed system to run old 90s Windows games for years though, and haven't picked up any significant issues. YMMV, it is Linux after all :P
Oh gosh. I'm getting heart palpitations :P
Is this a common attack vector then? Seems like an easy way to get an overflow error, or elevate privilege's.
Sandbox comes with a heavy usability price, so they are lax by default.
For example you protect your files, but then you can't load your photos to facebook because your browser doesn't have access.
There are some tradeoffs though. Some things like screen sharing might be worse on Wayland (e.g. I can't share a single window, only whole screens) and some apps don't support Wayland at all (including for example all of the IntelliJ IDEs). The latter can be circumvented by enabling XWayland (basically an X server running side by side with the Wayland compositor to handle X11-only apps). In that case you're left with the X11 security model for apps not running natively on Wayland.
I just like to bring that up even though it's not a common use case, because that's what keeps me from using Wayland.
Not sure what you're referring to. I'm using wayland and I can open multiple desktops via gdm.
It's a pretty elegant setup, honestly, and one thing I miss when I'm on Wayland. The idea is you're at a small desktop on your University's network and you need to use some of the computing power of the big data servers they have. So you run e.g. a graphing program that does all of its computation on the big data machine but does its display on your little desktop (in this setup the big data machine is called the "client" and the tiny little desktop is called the "server" which confuses people a lot at first but makes sense when you get into the architecture).
X itself had been moving away from this for years by adding some extensions that don't work well (or at all) over the network, but there are absolutely still lab setups that use the old way because it's pretty much tailor-made for it.
The bigger security issue was that X programs could see and modify certain things about each other and about the system as a whole, so for example the program XEyes had a pair of eyes that pointed at the location of the cursor (it sounds silly but this was an accessibility thing). And a screenshot program could take a shot of the screen. And so on. Wayland got rid of all those capabilities, but there turned out to be a lot of baby in that bathwater so they're slowly adding back each of them, one at a time. In another decade a new crop of developers will no doubt say "What's all this needless cruft?! Let's start over!" and the cycle of life will continue.
Obligatory XKCD: https://xkcd.com/1200/
Or, if you are truly paranoid... just create another Unix user for sensible web browsing and log in with that account:
useradd -m webcare
passwd webcare
I always read the script and do also verify they're only using ASCII chars (and if they're not, I check which Unicode shenanigan is ongoing).
For example:
... $ file /usr/local/bin/somescript.sh
/usr/local/bin/somescript.sh: Bourne-Again shell script, ASCII text executable
I haven't encountered this. You can execute scripts intentionally in vi, and I assume you could configure it to happen automatically, but can this happen without you making some sort of effort to enable it?
What scripts present such a risk? What vi configuration is required to stop this?
Same question wrt cat.
It's not easy. Just getting the mounts right is not sufficient. You also need to consider syscalls. E.g. TIOCSTI is permitted by default and allows an easy sandbox escape. See [0]CVE-2017-5226. TIOCLINUX can also allow sandbox escapes.
This can be prevented with the --new-session option, but that breaks interactive terminals, e.g. it causes ctrl-C to restore input to the parent shell while simultaneously running the child shell on the same terminal with the same inputs, which makes it unusable.
The alternative is compiling a seccomp BPF program to filter the syscalls, and loading it with the --seccomp option, but even this is non-trivial, e.g. see [1]CVE-2019-10063. This is also a case of "enumerating badness"; there's no guarantee that other syscalls are not also exploitable.
I've noticed a trend of adding N deeply intertwined features which then interact in N! different ways and no one bothers to define rigorous semantics for them. And then you have to get a PhD in Linux just to understand whether your system is vulnerable when you use POSIX message queues inside a FUSE filesystem inside an unprivileged user namespace inside chroot inside setarch running in 9 nested terminal sessions.
I think I'm starting to understand why some people swear by the BSDs.
Edit: just checked and OpenBSD has indeed removed TIOCSTI in 2017.
0% design and 100% scratch-my-itch tack on another feature.
Sandboxing a program that needs graphics performance anywhere near 10% of what the hardware is capable of is, at the moment, as we're stuck with X11 and growing gray hair waiting for Wayland to become a viable alternative, literally impossible.
Firejail does provide pre-made solutions like running nested X servers, which can sandbox graphical applications at insane resource costs, such that you might as well just run a full virtual machine.
Mount namespaces are security theater if you're giving access to X11, Pipewire, the SSH agent, the GPG agent, the dbus session bus, and god knows what else.
All you need to do is share the compositors socket and /dev/dri with the "container" and it "just works" for me!
I do not have xwayland enabled either, all of the software I use is wayland native!
I'm not a VIP, but I have some huge huge huge secrets that are worth at least a million dollars, maybe 10s of millions of dollars, that I need to access with a computer.
Malware means potentially losing millions or tens of millions of dollars. I'm so afraid of those secrets, I don't even access them on my windows computers unless necessary.
I'd love to be comfortable doing this, but given anyone can seemingly make a python keylogger, I'm not really comfortable using my computer(windows or linux) for this purpose. Gaming/updating my website/etc... all of that, who cares if I'm hacked, I got backups. I just havent found a great way to keep secrets that need to go online.