Re: NT/Exceed D.O.S.

From: Jamie Lawrence (jalat_private)
Date: Thu Apr 29 1999 - 11:54:14 PDT

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    I couldn't reproduce either effect with Exceed 6.1 under NTsp3.
    Everything behaved normally, both for new and existing sessions.
    
    -j
    
    At 01:57 PM 4/28/99 -0700, Matt Wilbur wrote:
    >Exceed (an X server, not an X emulator) version 6.0.1.0 on NT appears to
    >have fixed this problem, somewhat...
    >
    >Telnetting to port 6000 locks the server up for 20-30 seconds, but it
    >recovers eventually.  Not surprisingly, using netcat has the same effect...
    >although, contrary to Chris's findings with Exceed 5, I didn't need to send
    >any garbage characters, the connection alone did the job.  Also, it works
    >from any host, not just the one the xdm session had been initiated with,
    >regardless of host access settings in Xconfig, Exceeds "configuration" tool.
    >
    >
    >I'd still consider this DoS-bait, when you imagine a one-liner to
    >continuously connect to port 6000 of your favorite Exceed user's machine.
    >
    >Matt Wilbur
    >
    >[snip]
    >>
    >> This is regarding Hummingbird's Exceed X emulator v5 (and possibly v6)
    >> running on Windows NT.  I haven't tested Win95/98.
    >>
    >> The Exceed X server allows inbound TCP connections on port
    >> 6000 from the XDM> host.  If someone uses telnet from the XDM host to
    >connect to
    >> a PC running Exceed on port 6000 and enters any garbage text, the X server
    >
    >> will hang and the Exceed session is frozen for good.
    >>
    >> I have notified Hummingbird via their tech support web site
    >> but have not received a response yet.
    >>
    >> Chris LaFournaise
    >> cjlafournaiseat_private
    >>
    



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