Date: Tue Jun 21 01:04:46 2005
From: jnw at realvnc.com (James Weatherall)
Subject: RE: RealVNC/WinVNC Multiple vulnerabilities

"Class101",

If "NULL Session" means "No Authentication" then you may wish to contact
dfind's authors to have the text changed to something more appropriate.

"No Authentication" is not enabled by default, so servers must have been
explicitly configured that way.  You may wish to contact your site admins if
dfind is showing that your site is poorly configured.

There has never been an RFB protocol version 103.6, I'm afraid, so whatever
it is you're connecting to isn't RFB-compatible and so is not a VNC Server!

Cheers,

Wez @ RealVNC Ltd.


> -----Original Message-----
> From: class101@...eaker.net [mailto:class101@...eaker.net] 
> Sent: 20 June 2005 15:07
> To: James Weatherall
> Cc: vnc-list@...lvnc.com; 'Full-Disclosure'
> Subject: Re: RealVNC/WinVNC Multiple vulnerabilities
> 
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> 
> "RealVNC4 NULL Session" mean "no authentication" and there is tons of
> vnc using this UNsecured option.
> 
> as in my scan Radmin21 NULL Session mean also "no authentication" ,
> but they removed it in radmin22, do the same, because in some days,
> 
> isc sans is gonna cry on 5900 :)
> 
> 
> 
> 
> 
> there is no ssl ? well I have used what is returning many vnc on the
> internet, and on somes I got:
> 
> 
> 
> "RFB 103 006
> 
> the connection could not be established because SSL 3.0/TLS 1.0
> encryption is required"
> 
> 
> 
> prolly a mod from your src code, anyway thanx for letting me know :)
> 
> 
> James Weatherall a ?crit :
> 
> > "Class101",
> >
> > VNC has always provided the option to operate without requiring
> > authentication, there is no such thing as a "RealVNC4 NULL
> > Session", and VNC has never used SSL encryption, so I'm afraid it
> > sounds like someone's been telling you porkies!
> >
> > The output that you've included just seems to show that (assuming
> > "passworded" means "was able to guess password") your VNC Servers
> > have been configured with poorly chosen passwords.
> >
> > Of course, if you think you know of any viable attacks on VNC
> > servers then feel free to get in touch.
> >
> > Cheers,
> >
> > Wez @ RealVNC Ltd.
> >
> >
> >> -----Original Message----- From: vnc-list-admin@...lvnc.com
> >> [mailto:vnc-list-admin@...lvnc.com] On Behalf Of
> >> class101@...eaker.net Sent: 19 June 2005 15:35 To:
> >> vnc-list@...lvnc.com Cc: Full-Disclosure Subject: RealVNC/WinVNC
> >> Multiple vulnerabilities
> >>
> 
> > Two simple vulnerabilities wich may lead to an os guess + null
> > session + several others infos while scanning port 5900, low risk
> > on paper but high online risk:
> >
> > My 2cent suggestion to the realvnc team would be to totally remove
> > this "No Authentication" option wich wasnt present in the oldold
> > winvnc, and to standardize what is answering all your servers to
> > restrict the private informations guessing.
> >
> >
> > quick screenshot( of a simple dfind scanning test on a range that I
> > thought really secured :>):
> >
> > ***.7.41:5900 realvnc4 ssl encryption ***.16.83:5900 realvnc4
> > passworded (free ed. win32) ***.16.91:5900 realvnc4 passworded
> > (free ed. win32) ***.16.113:5900 realvnc4 passworded (free ed.
> > win32) ***.16.163:5900 realvnc4 passworded (free ed.
> > x86/SPARC/HPUX) ***.16.180:5900 realvnc4 passworded (free ed.
> > x86/SPARC/HPUX) ***.16.202:5900 RealVNC4 NULL Session (free ed.
> > x86/SPARC/HPUX) ***.16.237:5900 realvnc4 passworded (free ed.
> > x86/SPARC/HPUX) ***.22.217:5900 realvnc4 passworded (free ed.
> > x86/SPARC/HPUX) ***.29.91:5900 realvnc4 passworded (free ed.
> > x86/SPARC/HPUX) ***.29.92:5900 RealVNC4 NULL Session
> > (perso/enterp ed. win32 encryption:OFF) ***.29.93:5900 realvnc4
> > passworded (free ed. x86/SPARC/HPUX) ***.29.157:5900 realvnc4
> > passworded (perso/enterp ed. win32 encryption:OFF) ***.29.201:5900
> > realvnc4 passworded (free ed. x86/SPARC/HPUX) ***.29.234:5900
> > realvnc4 passworded (free ed. win32) ***.35.45:5900 realvnc4
> > passworded (perso/enterp ed. win32 encryption:ON) ***.40.192:5900
> > RealVNC4 NULL Session (perso/enterp ed. win32 encryption:ON)
> >
> > If you are seeking for more informations and you are from
> > @realvnc.com, email me, or else look at class101.org and
> > hat-squad.com
> >
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