POTENTIONAL FIX: etded.x86 getstatus exploit Options

[Guest_Dutchman_*]

Hi,

since a few months there is a exploit floating around abusing the getstatus requests to launch dos attacks against random targets and as a side effect creating massive lags on clients and the server.
Cause of this Yada from Staatsschutz.org made a patch for linux wich reduces the effectivity of this exploit.

etfix_getstatus 0.2 by yada / staatsschutz.org / jan. 2011
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This patch will ratelimit etded.x86 2.60b getstatus requests to 1 per IP every
4 seconds. This approach is not ideal as the real fix would be to change the
protocol to require some kind of handshake but this would break compatibility
with existing clients so its not really practical. The worst part is that the
patch is (in theory) vulnerable to a dos where legitimate clients could be
denied access to the getstatus command but i feel this is less of a headache
than kiddies using the server to flood random targets and thereby lagging the
server and pushing bandwith usage through the roof (master server is excluded
from ratelimit so no need to worry about it being denied using spoofed
packets).

Download the file right here.

A readme.txt, the sourcecode and a small howto are included.

Your free to distribute this file.

This post has been edited by Dutchman: Jan 6 2011, 11:33 AM

[Ligustah]

I just recently had to answer that question to someone else and I think came up with a rather simple example.

Suppose you have a mail box infront of your house. Every day you check the letters. There are some "spam" mails in there every day, so you sort them out right away and trash them, without even reading (or answering) them.
However, you cannot stop people from putting spam letters into your mailbox.

It's the same with software firewalls. You can prevent your server from "reading/answering" the packet, but it will still reach your machine (be put in its "mailbox"). There is nothing you can do about that, unless you control the upstream router (which you don't).

Hope this example clarifies the situation to people who might have not understood before.