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                             Luigi Auriemma

Application:  Winamp Web Interface
              https://www.flippet.org/wawi/
Versions:     <= 7.5.13
Platforms:    Windows (Winamp plugin)
Bugs:         A] buffer-overflow in FindBasicAuth
              B] browsing directory traversal
              C] buffer-overflow in the browse, download and load functions
              D] file extension check bypassing in file downloading
              E] lucky path name
Exploitation: remote, only bug A doesn't require privileges
Date:         10 Dec 2006
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
===============


Winamp Web Interface (Wawi) is a nice open source plugin for Winamp
(https://www.winamp.com) which allows the remote administration of the
media player through any web browser.


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


-----------------------------------
A] buffer-overflow in FindBasicAuth
-----------------------------------

FindBasicAuth() is the function located in security.cpp which parses
the Authorization HTTP field of the client's request.
Basically this function places, sequentially, the auth mode and base64
strings containing the username:password fields in the temp buffer of
only 100 bytes and then decodes this string using the userpass buffer
ever of 100 bytes.
The operation is made through the GetAString() function which limits
the strings at 255 chars.

In my tests doesn't seem possible to exploit the bug for executing
remote code.
This is the only vulnerability which doesn't require privileges for
being exploited.


-------------------------------
B] browsing directory traversal
-------------------------------

The Browse() function located in browse.cpp is used for showing the
available files in a specific folder within the root directory.
The function (as all the others in the program) checks the path
received by the client using the GoodPath() function which verifies if
exist risks caused by sequential dots and backslashes (like \..\).

The problem here is that slashes are correctly converted in backslashes
before the calling of this function but the hex slashes %2f aren't
allowing the browsing of any folder (files are limited by the
extensions specified in the configuration) in the disk where is located
the root directory.

As already said only browsing is possible, not downloading.
The attacker needs the "Browse" privilege for exploiting this bug.


-------------------------------------------------------------
C] buffer-overflow in the browse, download and load functions
-------------------------------------------------------------

The Browse(), CControl::Download() and CControl::Load() functions are
affected by some buffer-overflow caused by the creation of a string
containing the root directory plus the path string received from the
client using a buffer of only MAX_PATH bytes (260, the same size of the
client string).

The attacker needs the required privileges related to the function he
wants to exploit.


-----------------------------------------------------
D] file extension check bypassing in file downloading
-----------------------------------------------------

Wawi has also a check for allowing the dowloading of some types of
files by the users with the "Download" permission.
In the "Music Collections" section of the Wawi configuration we can
find two switches for allowing the viewing or the downloading of the
Winamp files and all the others.

CControl::Download() calls the IsWinampFile() function for checking if
the requested filename is supported by Winamp and then allows the
downloading if the related option has been selected.

A dot after the requested filename will allow an attacker with the
"Download" privilege to download any file of any extension located in
the root directory.

Note: this is not really a bug of Wawi but I report it here since it's
one of the rare cases in which it can be exploited maliciously.


------------------
E] lucky path name
------------------

Any of the functions used for handling the files (like browsing,
loading, downloading and so on) requires a backslash before the path
or file name, like https://localhost/browse?path=\
If exists another folder or file which begins with the same name of the
root directory is possible to use it instead of that of the
configuration.

For example if the root directory is c:\folder and the attacker use
https://localhost/browse?path=2 he will browse c:\folder2 if it exists,
or he can also download the file c:\folder2.mp3 ever if it exists.

The required privileges (and the usual luck!) are needed for exploiting
this bug.


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


A] https://localhost/browse
   then insert an username longer than 100 chars

B] https://localhost/browse?path=%2f..%2f..%2f

C] https://localhost/dl?file=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

D] https://localhost/dl?file=\file.txt.


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


This program is no longer supported.


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--- 
Luigi Auriemma
https://aluigi.org
https://mirror.aluigi.org