Re: VNC viewers: Clipboard of host automatically sent to remote machine

[GloW - XD <doomxd () gmail com>]

INSECURE i mean*


On 25 January 2012 21:30, Christian Sciberras <uuf6429 () gmail com> wrote:
> That's not necessarily true. On windows you can add custom clipboard formats
> that would contain a 'link' to the original source, causing the data to be
> actually
> passed when pasting. An example of this is when one copy+pastes a file.
> See the Windows Clipboard API for more info.
>
> Chris.
>
>
>
> On Wed, Jan 25, 2012 at 10:54 AM, Mario Vilas <mvilas () gmail com> wrote:
> > I'm not sure how the clipboard works in Linux desktops (I understand
> > it's a little different), but at least in Windows environments data
> > has to be copied to the clipboard when you hit Ctrl-C. It can't be
> > copied when you hit Ctrl-V because then the applications wouldn't know
> > if there is anything to paste (like you said, the button would be
> > grayed).
> >
> > So to replicate this behavior it's necessary to send the data as it's
> > copied, not as it's pasted. Most (not all, but most) desktop systems
> > assume clipboard data can be freely shared with all applications and
> > don't have any kind of isolation at all. VNC was designed with the
> > same idea.
> >
> > The bottom line is, the problem here is using VNC for what Ben is
> > using it. There are many more problems with that scenario and
> > clipboard sharing may be the least of them.
> >
> > On Wed, Jan 25, 2012 at 8:44 AM, Peter Osterberg <j () vel nu> wrote:
> > > On 01/24/2012 07:18 PM, Mario Vilas wrote:
> > > > > Guys, could you please read carefully everything before you reply?
> > > > I read carefully. It still didn't make sense, though.
> > > >
> > > > > And you wouldn't be allowed to use copy&paste while you edit sensitive
> > > > > documents either, I guess?
> > > > I don't know how you could get to such a conclusion from what I wrote.
> > > >
> > > > You're reporting that if you copy and paste sensitive information and
> > > > connect to a VNC session your clipboard data gets sent to the remote
> > > > machine. That's pretty obvious and not a security hole that needs to
> > > > be plugged.
> > >
> > > I don't think that is what Ben is saying. The clipboard get sent to the
> > > the server even before it is pasted, this happens without the user
> > > knowing of it.
> > >
> > > Notepad would have the paste button grayed otherwise, if the clipboard
> > > is empty, right? So it is already on the server before paste is pressed.
> > >
> > > So what ever was in the clipboard buffer is transmitted to the server on
> > > connection.
> > >
> > > This is at least the assumption I make from reading Ben's mails. Or...
> > > Is there a cliboard flag saying there is something on the clipboard, but
> > > it isn't transmitted until the user actually pastes? I haven't really
> > > got any experience with how the clipboard feature is implemented. My
> > > assumption is however that it has to be on server for notepad to be
> > > aware that Paste shouldn't be grayed out...
> > >
> > > I think Ben's report make complete sense actually, it would be better to
> > > have the clipboard feature as a default. Security before features... =)
> > >
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>
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_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/