full-disclosure - Server crash in Flash Messaging 5.2.0g

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From: aluigi at autistici.org (Luigi Auriemma)
Subject: Server crash in Flash Messaging 5.2.0g

#######################################################################

                             Luigi Auriemma

Application:  Flash Messaging
              http://www.flashmessage.com
Versions:     <= 5.2.0g (rev 1.1.2)
Platforms:    Windows
Bugs:         - server crash
              - unkickable clients
Exploitation: remote, versus server
Date:         07 October 2004
Author:       Luigi Auriemma
              e-mail: aluigi@...ervista.org
              web:    http://aluigi.altervista.org

#######################################################################

1) Introduction
2) Bugs
3) The Code
4) Fix

#######################################################################

===============
1) Introduction
===============

Flash Messaging is an instant messanger for Windows and uses a
client-server architecture.

#######################################################################

=======
2) Bugs
=======

The network data exchanged between server and clients is composed by
wide chars (16 bits) and the server is not able to handle some of these
chars, the result is the immediate crash of the server.

Another bug (but very minor, just a joke) is that the shutdown command
(and any other available command) that the server can send to users to
immediately terminate their clients is just only a command that can be
easily ignored, in fact the connection will not be interrupted so the
modified clients can continue to stay connected and to chat without
problems.

#######################################################################

===========
3) The Code
===========

  http://aluigi.altervista.org/poc/flashmsg.zip

This proof-of-concept can act also as a client emulator and data
decoder, so is possible to see any raw data sent by the server and
moreover to test the "unkickable clients" problem I showed before.

#######################################################################

======
4) Fix
======

No fix.
No reply from the vendor.

#######################################################################

--- 
Luigi Auriemma
http://aluigi.altervista.org