Critical Denial of Service bugs in Discover

[Ben Cooksley]

On Thu, Feb 10, 2022 at 8:20 AM Aleix Pol <aleixpol at kde.org> wrote:

> [Snip]
>
> We still haven't discussed here is how to prevent this problem from
> happening again.
>
> If we don't have information about what is happening, we cannot fix
> problems.
>

Part of the issue here is that the problem only came to Sysadmin attention
very recently, when the system ran out of disk space as a result of growing
log files.
It was at that point we realised we had a serious problem.

Prior to that the system load hadn't climbed to dangerous levels (> number
of CPU cores) and Apache was keeping up with the traffic, so none of our
other monitoring was tripped.

If you have any thoughts on what sort of information you are thinking of
that would be helpful.

It would definitely be helpful though to know when new software is going to
be released that will be interacting with the servers as we will then be
able to monitor for abnormalities.
(This would have allowed us to advise on the User-Agent stuff prior to
September, as well as point out potential issues with caching


> Is there anything that could be done in this front? The issue here
> could have been addressed months ago, we just never knew it was
> happening.


One possibility that did occur to me today would be for us to integrate
some kind of killswitch that our applications would check on first
initialisation of functionality that talks to KDE.org servers.
This would allow us to disable the functionality in question on user
systems.

The check would only be done on first initialization to keep load low,
while still ensuring all users eventually are affected by the killswitch
(as they will eventually need to logout/reboot for some reason or another).

The killswitch would probably work best if it had some kind of version
check in it so we could specify which versions are disabled.
That would allow for subsequent updates - once delivered by distributions -
to restore the functionality (while leaving it disabled for those who
haven't updated).


>
> Aleix
>

Thanks,
Ben
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