If AV suddenly stops working, it could mean the AV is compromised. A BSOD is a desirable outcome in that case. Booting a compromised system anyway is bad code.
Comment on CrowdStrike downtime apparently caused by update that replaced a file with 42kb of zeroes
deadbeef79000@lemmy.nz 1 month agoPoorly written code can’t.
In this case:
- Load config data
- If data is valid:
- Use config data
- If data is invalid:
- Crash entire OS
Is just poor code.
ChairmanMeow@programming.dev 1 month ago
CeeBee_Eh@lemmy.world 1 month ago
You know there’s a whole other scenario where the system can simply boot the last known good config.
ChairmanMeow@programming.dev 1 month ago
And what guarantees that that “last known good config” is available, not compromised and there’s no malicious actor trying to force the system to use a config that has a vulnerability?
CeeBee_Eh@lemmy.world 1 month ago
The following:
- An internal backup of previous configs
- Encrypted copies
- Massive warnings in the system that current loaded config has failed integrity check
There’s a load of other checks that could be employed. This is literally no different than securing the OS itself.
This is essentially a solved problem, but even then it’s impossible to make any system 100% secure. As the person you replied to said: “this is poor code”
Takios@discuss.tchncs.de 1 month ago
I agree that the code is probably poor but I doubt it was a conscious decision to crash the OS.
The code is probably just:
- Load config data
- Do something with data
And 2 fails unexpectedly because the data is garbage and wasn’t checked if it’s valid.
Morphit@feddit.uk 1 month ago
You can still catch the error at runtime and do something appropriate. That might be to say this update might have been tampered with and refuse to boot, but more likely it’d be to just send an error report back to the developers that an unexpected condition is being hit and just continuing without loading that one faulty definition file.
CeeBee_Eh@lemmy.world 1 month ago
If there’s an error, use last known good config. So many systems do this.
5C5C5C@programming.dev 1 month ago
When talking about the driver level, you can’t always just proceed to the next thing when an error happens.
Imagine if you went in for open heart surgery but the doctor forgot to put in the new valve while he was in there. He can’t just stitch you up and tell you to get on with it, you’ll be bleeding away inside.
In this specific case we’re talking about security for business devices and critical infrastructure. If a security driver is compromised, in a lot of cases it may legitimately be better for the computer to not run at all, because a security compromise could mean it’s open season for hackers on your sensitive device. We’ve seen hospitals held random, we’ve seen customer data swiped from major businesses. A day of downtime is arguably better than those outcomes.
The real answer here is crowdstrike needs a more reliable CI/CD pipeline. A failure of this magnitude is inexcusable and represents a major systemic failure in their development process. But the OS crashing as a result of that systemic failure may actually be the most reasonable desirable outcome compared to any other possible outcome.
Morphit@feddit.uk 1 month ago
This error isn’t intentionally crashing because of a security risk, though that could happen. It’s a null pointer exception, so there are no static or runtime checks that could have prevented or handled this more gracefully. This was presumably a bug in the driver for a long time, then a faulty config file came and triggered the crashes. Better static analysis and testing of the kernel driver is one aspect, how these live config updates are deployed and monitored is another.
deadbeef79000@lemmy.nz 1 month ago
In which case this should’ve been documented behaviour and probably configurable.
CeeBee_Eh@lemmy.world 1 month ago
That’s a bad analogy. CrowdStrike’s driver encountering an error isn’t the same as not having disk IO or a memory corruption. If CrowdStrike’s driver didn’t load at all the system could still boot.
It should absolutely be expected that if the CrowdStrike driver itself encounters an error, there should be a process that allows the system to gracefully recover. The issue is that CrowdStrike likely thought of their code as not being able to crash as they likely only ever tested with good configs, and thus never considered a graceful failure of their driver.
5C5C5C@programming.dev 1 month ago
I don’t doubt that in this case it’s both silly and unacceptable that their driver was having this catastrophic failure, and it was probably caused by systemic failure at the company, likely driven by hubris and/or cost-cutting measures.
Although I wouldn’t take it as a given that the system should be allowed to continue if the anti-virus doesn’t load properly more generally.
For an enterprise business system, it’s entirely plausible that if a crucial anti-virus driver can’t load properly then the system itself may be compromised by malware, or at the very least the system may be unacceptably vulnerable to malware if it’s allowed to finish booting. At that point the risk of harm that may come from allowing the system to continue booting could outweigh the cost of demanding manual intervention.
In this specific case, given the scale and fallout of the failure, it probably would’ve been preferable to let the system continue booting to a point where it could receive a new update, but all I’m saying is that I’m not surprised more generally that an OS just goes ahead and treats an anti-virus driver failure at BSOD worthy.