Piwik <= 2.16.0 (saveLayout) PHP 对象注入漏洞

The vulnerability can be triggered through the saveLayout() method defined in /plugins/Dashboard/Controller.php: ``` 210. public function saveLayout() 211. { 212. $this->checkTokenInUrl(); 213. 214. $layout = Common::unsanitizeInputValue(Common::getRequestVar('layout')); 215. $layout = strip_tags($layout); 216. $idDashboard = Common::getRequestVar('idDashboard', 1, 'int'); 217. $name = Common::getRequestVar('name', '', 'string'); 218. 219. if (Piwik::isUserIsAnonymous()) { 220. $session = new SessionNamespace("Dashboard"); 221. $session->dashboardLayout = $layout; 222. $session->setExpirationSeconds(1800); ``` User input passed by anonymous users through the "layout" request parameter is being stored into a session variable at line 221, and this is possible by invoking an URL like this: ``` http://[piwik]/index.php?module=Dashboard&action=saveLayout&token_auth=anonymous&layout=[injection]%26%2365536; ``` Since Piwik is not using "utf8mb4" collations for its database, this can be exploited in combination with a MySQL UTF8 truncation issue in order to corrupt the session array, allowing unauthenticated attackers to inject arbitrary PHP objects into the application scope and carry out Server-Side Request Forgery (SSRF) attacks, delete arbitrary files, execute arbitrary PHP code, and possibly other attacks. Successful exploitation of this vulnerability requires Piwik to use the database to store session data (dbtable option) and the application running on PHP before version 5.4.45, 5.5.29, or 5.6.13.