[Full-disclosure] Postnuke 0.750 - 0.760rc4 local file inclusion

[pokley <pokleyzz@xxxxxxxxxxxxxxxxxxx>]

Product : Postnuke 0.750 (http://www.postnuke.com)
Description: Postnuke 0.750 - 0.760rc4 local file inclusion
Severity: High

Description
===========
Postnuke is Web Content Management System written in PHP and using mysql
as database backend.

Detail
======

Directory traversal in function pnModFunc
-----------------------------------------

We have found serious vulnerability which allow any user to view/include  
local file in function pnModFunc. This is due to lack of error checking in  
function pnModFunc when user supply func through index.php. func variable  
will sanitize using pnVarCleanFromInput which will remove any slashes  
before pass to pnModFunc in index.php. This make nullbyte poisoning  
possible. With the help from pnlang directory in Blocks module this  
vulnerability is very easy to exploit. Remote code execution also possible  
with help of 3rd party module which allow image upload or through  
accesible apache log file.

--pnMod.php--
    } else {
    if(file_exists("modules/$modname/pn$type/$func.php"))
        {

                require_once("modules/$modname/pn$type/$func.php");<-- THE 
PROBLEM

        return $modfunc($args);
        }
-------------

Proof of concept
================
http://server.com/index.php?module=Blocks&type=lang&func=../../../../../../etc/passwd%00

Fix
===
Fix Available from postnuke cvs since 5th May 2005

http://cvs.postnuke.com/viewcvs.cgi/Historic_PostNuke_Library/postnuke-devel/html/includes/pnMod.php.diff?r1=1.47&r2=1.48

http://cvs.postnuke.com/viewcvs.cgi/Historic_PostNuke_Library/postnuke-devel/html/
index.php.diff?r1=1.39&r2=1.40

Vendor Response
===============
3rd May 2005 - Vendor contacted
4th May 2005 - Vendor Reply
5th May 2005 - Fix Available

Thanks
======
Andreas Krapoh from postnuke for fast response in this issue.



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