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                             Luigi Auriemma

Application:  ActivePost Standard
              http://www.activepost.net
Versions:     <= 3.1
Platforms:    Windows
Bugs:         - File-Server crash
              - File-server directory traversal and path disclosure
              - conference password disclosure
Risk:         critical
Exploitation: remote, versus server
              (only the third bug affects clients too)
Date:         23 September 2004
Author:       Luigi Auriemma
              e-mail: aluigi@altervista.org
              web:    http://aluigi.altervista.org


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


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


ActivePost Standard is an interesting communication program for
companies.
It is constituited by the clients and a central server used for login,
messaging, chat, files transfer and conferences.


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


--------------------
A] File-Server crash
--------------------

The file-server runs on port 6004 and is used to upload files on the
server so they can be downloaded by the target users.
The problem is that an attacker is able to crash the file-server using
a filename longer than 4074 chars.
The file-server protocol is constituited by data blocks of 4104 bytes
and doesn't seem possible to cause more damage.


------------------------------------------------------
B] File-server directory traversal and path disclosure
------------------------------------------------------

This is the most critical vulnerability because lets an attacker to
upload malicious files everywhere in the disk on which is installed the
ActivePost server overwriting any existing file.
That happens exploiting a directory traversal bug in the name of the
file to upload using the slash char.
Example: /../../../windows/calc.exe
The complete real path in which the remote file has been written is
ever visible after each upload because this information is directly
sent by the server.


---------------------------------
C] conference password disclosure
---------------------------------

Everytime an user enters in the conference menu, the server sends all
the informations of the available rooms included the plain-text
passwords of those protected.
Check the following example data received from the server:

 4703 0000 0000 0000 0000 0000 0000 0000  G...............
 0000 0000 0a72 6f6f 6d20 7469 746c 6500  .....room title.
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0001 3100  ..............1.
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0e73 6563 7265 7470 6173 7377 6f72  ...secretpasswor <===
 6400 0000 0000 0000 0000 0000 0000 0000  d...............
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0003 3832  ..............82
 3100 0000 0000 0000 0000 0000 0000 0000  1...............
 0000 0138 0000 0000 0000 0000 0000 0000  ...8............
 0000 0000 0000 0017 6465 7363 7269 7074  ........descript
 696f 6e20 6f66 2074 6865 2072 6f6f 6d00  ion of the room.
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000 0000 0000 0000 0000 0000 0000  ................
 0000 0000                                ....


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


A] http://aluigi.altervista.org/poc/actpboom.zip

B] http://aluigi.altervista.org/poc/actpup.zip

C] launch a sniffer before entering in the conference menu


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


No fix.
No reply from the developers.


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