#335 - Users can inject arbitrary data into Pyhoca-GUI via .bashrc

X2Go Bug report logs - #335
Users can inject arbitrary data into Pyhoca-GUI via .bashrc

Reported by: "Dan Halbert" <halbert@halwitz.org>

Date: Mon, 21 Oct 2013 12:48:02 UTC

Severity: grave

Tags: confirmed, pending

Fixed in version 0.4.0.9

Done: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>

Bug is archived. No further changes may be made.

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Date: Tue, 29 Oct 2013 13:41:47 +0000
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From: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>
To: 333@bugs.x2go.org, control@bugs.x2go.org
Subject: Re: [X2Go-Dev] Bug#333: Users can inject arbitrary data into X2Go
 Client via .bashrc
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clone #333 -1 reassign -1 python-x2go retitle -1 Users can inject arbitrary data into Pyhoca-GUI via .bashrc thanks Hi All, On Di 29 Okt 2013 13:36:14 CET, Mike Gabriel wrote: > Hi All, > > Dan Halbert made me aware of it being easily possible to inject > arbitrary data into X2Go Client via the server-side .bashrc file. > This surely is a security problem in X2Go. > > Thus, I found that we really need to do some sanity checks on > incoming output from X2Go Servers to avoid such injections. > > The idea is to invoke the server-side command with a UUID hash > before and after the actuall command invocation: > > 1. execute server-side command from X2Go Client: > > ssh <user>@<server> sh -c "echo <uuidhash> && <x2gocmd> && echo <uuidhash> > > 2. read data from X2Go Server: > > X2GODATABEGIN:<uuidhash> > <x2godata_line1> > <x2godata_line2> > .... > <x2godata_lineN> > X2GODATAEND:<uuidhash> > > 3. cut out the X2Go data returned by the server (in C++): > > QString begin_marker = "X2GODATABEGIN:"+uuid+"\n"; > QString end_marker = "X2GODATAEND:"+uuid+"\n"; > int output_begin=stdOutString.indexOf(begin_marker) + \\ > begin_marker.length(); > int output_end=stdOutString.indexOf(end_marker); > output = stdOutString.mid(output_begin, \\ > output_end-output_begin); > > > I have a patch locally for this and will commit it in a minute. We > can discuss the patch and move on from there when it's there. > > Unfortunately, this patch does not fix #327 as it is impossible to > use scp with echoing .bashrc files. With this patch applied, the > session starts, but setting up the SSHfs shares fails with locking > up X2Go Client. > > For people who depend on echoing .bashrc files, please read my last > post on #327. > > Mike This actually also applies to Python X2Go. Mike -- DAS-NETZWERKTEAM mike gabriel, herweg 7, 24357 fleckeby fon: +49 (1520) 1976 148 GnuPG Key ID 0x25771B31 mail: mike.gabriel@das-netzwerkteam.de, http://das-netzwerkteam.de freeBusy: https://mail.das-netzwerkteam.de/freebusy/m.gabriel%40das-netzwerkteam.de.xfb

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X2Go Bug report logs - #335 Users can inject arbitrary data into Pyhoca-GUI via .bashrc

X2Go Bug report logs - #335
Users can inject arbitrary data into Pyhoca-GUI via .bashrc