X2Go Bug report logs - #509
Document NX/X11 security issue: clipboard sniffing

Package: wiki.x2go.org; Maintainer for wiki.x2go.org is x2go-dev@lists.x2go.org;

Reported by: Christoph Anton Mitterer <calestyo@scientia.net>

Date: Mon, 1 Jul 2013 02:48:02 UTC

Severity: grave

Tags: security

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X-Loop: owner@bugs.x2go.org
Subject: Bug#258: [X2Go-User] Limiting clipboard sharing
Reply-To: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>, 258@bugs.x2go.org
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From: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>
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[Message part 1 (text/plain, inline)]
Hi Kris,

On  Mo 27 Jan 2014 18:46:59 CET, Kris Ilowiecki wrote:

> Hello,
>
> I am quite new to X2Go, and really impressed by it. I'd like to  
> switch from opennx to X2Go, but I can't find a way to limit  
> clipboard sharing.
>
> Opennx, as well as other NX forks, has the options to enable clipboard
> sharing both ways, one-way, or disable it completely. So far I have  
> failed to find a setting to limit this in X2Go.
>
> I'd need clipboard sharing to work only in the client->server
> direction, or at least to disable it completely.
>
> I have searched for it for quite a while, but the best I have  
> managed to find is a bug report
> http://bugs.x2go.org/cgi-bin/bugreport.cgi?bug=258
> and a mailing list question without a single reply.
>
> Is there some way to configure it?
> If not, is it going to be hard to write a patch that would turn
> this off at compilation time?
> I've also been thinking of using some external programs to achieve  
> the effect, e.g. putting X2Go inside Xephyr, or the other way round...
>
> Any hints most welcome
>
> Many thanks,
> Kris

There should be two approaches...

 1) disable clipboard server-side for all users
 2) disable clipboard in X2Go Client / PyHoca-GUI on the client-side

The first is easy. Please look at /usr/bin/x2gostartagent of  
x2goserver package and make clipboard configurable via  
/etc/x2go/x2goserver.conf. Send a patch to our BTS [1].

The second approach is for us devs, I guess...

The workaround provided by Mike#2 is a fine approach, but not a real  
solution to this problem.

Mike#1

[1] http://wiki.x2go.org/doku.php/wiki:bugs
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