Morphit

I remember doing this with dbus but I can’t find that set-up anymore. This stackoverflow answer looks a bit more elegant: https://unix.stackexchange.com/a/128007/37570

A little script could run your command when matching the jack/headphone events from acpi_listen.

You fraud.

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Well at that point, just don’t install any kernel mode EDR software at all.

NixOS can be set up for impermanence where all config is recreated every boot and nothing persists besides the nix store. There’s helpers for ephemeral home also, so you can have something like TailsOS. I’m sure you could do that with other distros but you’d need absolute discipline to have everything the machine needs provisioned at boot.

I think having an A partition and a B partition (I’m assuming that’s how SteamOS works) wouldn’t help in this case. If the A partition downloaded the definition file, crashed and failed to reboot; the bootloader could failover to the B partition - which would then download the definition file, crash and fail to reboot. It would have to keep rolling back to a last known good snapshot until the update got withdrawn.

You could have an ephemeral set up that wipes /var and /etc and recreates them every boot. I don’t think these EDR tools would like that very much though.

What do you mean? The shadow mask ensures the gun for each colour can only hit the phosphors of that colour. How would a lower resolution change that?

As far as we know, the input was a file filled with zeroes

CrowdStrike have said that was not the problem:

This is not related to null bytes contained within Channel File 291 or any other Channel File.

That said, their preliminary incident review doesn’t give us much to go on as to what was wrong with the file.

You’re speculating that it was something easy to test for by a third party. It certainly could have been but I would hope it’s a more subtle bug which, as you say, can’t be exhaustively tested for. Source code analysis definitely would have surfaced this bug so either they didn’t bother looking or didn’t bother fixing it.

How would you prove that no input exists that could crash a piece of code? The potential search space is enormous. Microsoft can’t prevent drivers from accepting external input, so there’s always a risk that something could trigger an undetected error in the code. Microsoft certainly ought to be fuzz testing drivers it certifies but that will only catch low hanging fruit. Unless they can see the source code, it’s hard to determine for sure that there are no memory safety bugs.

The driver developers are the ones with the source code and should have been using analysis tools to find these kinds of memory safety errors. Or they could have written it in a memory safe language like Rust.

Yeah, you’d need to snapshot their data directory and roll that back. The previous kernel module may well have had the bug already, just not a malformed config file to trip it.

Also, if the driver booted ok, but then panicked soon after, would that count as a bad boot? The description seems to indicate the boot counters get reset as soon as a boot succeeds.

It’s a proprietary config file. I think it’s a list of rules to forbid certain behaviours on the system. Presumably it’s downloaded by some userland service, but it has to be parsed by the kernel driver. I think the files get loaded ok but the driver crashes when iterating over an array of pointers. Possibly these are the rules and some have uninitialised pointers but this is speculation based on some kernel dumps on twitter. So the bug probably existed in the kernel driver for quite a while, but they pushed a (somehow) malformed config file that triggered the crash.

For this Channel File, yes. I don’t know what the failure rate is - this article mentions 40-70%, but there could well be a lot of variance between different companies’ machines.

The driver has presumably had this bug for some time, but they’ve never had a channel file trigger it before. I can’t find any good information on how they deploy these channel files other than that they push several changes per day. One would hope these are always run by a diverse set of test machines to validate there’s no impact to functionality but only they know the procedure there. It might vary based on how urgent a mitigation is or how invasive it’ll be - though they could just be winging it. It’d be interesting to find out exactly how this all went down.

It should be relatively straightforward to script the recovery of cloud VM images (even without snapshots). Good luck getting the unwashed masses to follow a script to manually enter recovery mode and delete files in a critical area of the OS.

How does Falcon store these channel files on Linux? I don’t know how an immutable distro would handle this given CrowdStrike push several of these updates per day and presumably use their own infrastructure to deploy them.

I guess if you pay them enough they could customize the deployment to work with whatever infrastructure you have but it’s all proprietary so I have no idea if they’re really doing that anywhere.

I’d have thought the cloud side would be pretty easy to script over. Presumably the images aren’t encrypted from the host filesystem so just ensure each VM is off, mount its image, delete the offending files, unmount the image and start the VM back up. Check it works for a few test machines then let it rip on the whole fleet.

Same. I can see some of it in between popovers about my account being suspended, getting rate limited, or of course “something went wrong”. I don’t understand why there are people who still only post there.

It’s a proprietary enterprise security product so I think it’ll be difficult to get information until they give a proper post-mortem (if they do so). Here’s hoping someone can put it all together though.

From what we have from CrowdStrike so far, the Channel File 291 update was to combat some use of Named Pipes in Windows malware.

This seems to have triggered a null pointer exception in the Falcon kernel driver as it loaded this Channel File. CrowdStrike say this is not related to the large null sections of one of the files but haven’t really explained what did trigger it.

Regardless, the kernel driver ought to have been statically analysed to detect this kind of memory hazard, or written in a language that prevents this class of bugs altogether. This is a priority of the US government right now, but CrowdStrike doesn’t seem to have got the memo.

It’s not that clear cut a problem. There seems to be two elements; the kernel driver had a memory safety bug; and a definitions file was deployed incorrectly, triggering the bug. The kernel driver definitely deserves a lot of scrutiny and static analysis should have told them this bug existed. The live updates are a bit different since this is a real-time response system. If malware starts actively exploiting a software vulnerability, they can’t wait for distribution maintainers to package their mitigation - they have to be deployed ASAP. They certainly should roll-out definitions progressively and monitor for anything anomalous but it has to be quick or the malware could beat them to it.

This is more a code safety issue than CI/CD strategy. The bug was in the driver all along, but it had never been triggered before so it passed the tests and got rolled out to everyone. Critical code like this ought to be written in memory safe languages like Rust.

I’d unsubscribe from !linux@lemmy.ml for a start.

I’m pretty sure this update didn’t get pushed to linux endpoints, but sure, linux machines running the CrowdStrike driver are probably vulnerable to panicking on malformed config files. There are a lot of weirdos claiming this is a uniquely Windows issue.

IFERROR(;0)

Maybe they should use a more appropriate development tool for their critical security platform than Excel.