Nytro Posted April 26, 2013 Report Posted April 26, 2013 [h=1]phpMyAdmin 3.5.8 and 4.0.0-RC2 - Multiple Vulnerabilities[/h][waraxe-2013-SA#103] - Multiple Vulnerabilities in phpMyAdmin===============================================================================Author: Janek Vind "waraxe"Date: 25. April 2013Location: Estonia, TartuWeb: http://www.waraxe.us/advisory-103.htmlDescription of vulnerable software:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~phpMyAdmin is a free software tool written in PHP, intended to handle theadministration of MySQL over the World Wide Web. phpMyAdmin supports a widerange of operations with MySQL.http://www.phpmyadmin.net/home_page/index.php###############################################################################1. Remote code execution via preg_replace() in "libraries/mult_submits.inc.php"###############################################################################Reason: 1. insufficient sanitization of user data before using in preg_replaceAttack vectors: 1. user-supplied parameters "from_prefix" and "to_prefix"Preconditions: 1. logged in as valid PMA user 2. PHP version < 5.4.7 (Newer versions: Warning: preg_replace(): Null byte in regex)PMA security advisory: PMASA-2013-2CVE id: CVE-2013-3238Affected phpMyAdmin versions: 3.5.8 and 4.0.0-RC2Result: PMA user is able to execute arbitrary PHP code on webserverLet's take a look at the source code:Php script "libraries/mult_submits.inc.php" line 426 (PMA version 3.5.8):------------------------[ source code start ]----------------------------------case 'replace_prefix_tbl': $current = $selected[$i]; $newtablename = preg_replace("/^" . $from_prefix . "/", $to_prefix, $current); $a_query = 'ALTER TABLE ' . PMA_backquote($selected[$i]) . ' RENAME ' . PMA_backquote($newtablename) ; // CHANGE PREFIX PATTERN $run_parts = true; break;case 'copy_tbl_change_prefix': $current = $selected[$i]; $newtablename = preg_replace("/^" . $from_prefix . "/", $to_prefix, $current); $a_query = 'CREATE TABLE ' . PMA_backquote($newtablename) . ' SELECT * FROM ' . PMA_backquote($selected[$i]) ; // COPY TABLE AND CHANGE PREFIX PATTERN $run_parts = true; break;------------------------[ source code end ]------------------------------------We can see, that PHP variables "$from_prefix" and "$to_prefix" are used inpreg_replace function without any sanitization. It appears, that those variablesare coming from user submitted POST request as parameters "from_prefix" and"to_prefix". It is possible to inject e-modifier with terminating null byte viafirst parameter and php code via second parameter. In case of successfulexploitation injected PHP code will be executed on PMA webserver.Tests:1. Log in to PMA and select database:http://localhost/PMA/index.php?db=test&token=25a6ce9e288070bd28c3f9aebffad1b82. select one table from database by using checkbox and then select"Replace table prefix" from select control "With selected:".3. We can see form named "Replace table prefix:" with two input fields.Type "/e%00" to the "From" field and "phpinfo()" to the "To" field.4. Activate Tamper Data Firefox add-on:https://addons.mozilla.org/en-us/firefox/addon/tamper-data/5. Click "Submit", Tamper Data pops up, choose "Tamper".6. Now we can modify POST request. Look for parameter "from_prefix".It should be "%2Fe%2500", remove "25", so that it becomes "%2Fe%00".Click "OK" and Firefox will send out manipulated POST request.7. We are greeted by phpinfo function output - code execution is confirmed.PMA version 4.0.0-RC2 contains almost identical vulnerability:Php script "libraries/mult_submits.inc.php" line 482 (PMA version 4.0.0-RC2):------------------------[ source code start ]----------------------------------case 'replace_prefix_tbl': $current = $selected[$i]; $newtablename = preg_replace("/^" . $_POST['from_prefix'] . "/", $_POST['to_prefix'], $current); $a_query = 'ALTER TABLE ' . PMA_Util::backquote($selected[$i]) . ' RENAME ' . PMA_Util::backquote($newtablename); // CHANGE PREFIX PATTERN $run_parts = true; break;case 'copy_tbl_change_prefix': $current = $selected[$i]; $newtablename = preg_replace("/^" . $_POST['from_prefix'] . "/", $_POST['to_prefix'], $current); $a_query = 'CREATE TABLE ' . PMA_Util::backquote($newtablename) . ' SELECT * FROM ' . PMA_Util::backquote($selected[$i]); // COPY TABLE AND CHANGE PREFIX PATTERN $run_parts = true; break;------------------------[ source code end ]------------------------------------############################################################################2. Locally Saved SQL Dump File Multiple File Extension Remote Code Execution############################################################################Reason: 1. insecure names of locally saved dump filesAttack vectors: 1. user-supplied POST parameter "filename_template"Preconditions: 1. logged in as valid PMA user 2. configuration setting "SaveDir" defined and pointed to directory, which is writable for php and directly accessible over web(by default "SaveDir" is empty and PMA is secure) 3. Apache webserver with unknown MIME for "sql" extensionPMA security advisory: PMASA-2013-3CVE id: CVE-2013-3239Affected are PMA versions 3.5.8 and 4.0.0-RC2There is a security weakness in a way, how PMA handleslocally saved database dump files. It is possible, that saveddump file has multiple extensions and if Apache webserver does notknow MIME type of "sql" extension (that's how it is by default),then for example "foobar.php.sql" file will be treated as php file.More information:http://httpd.apache.org/docs/2.2/mod/mod_mime.htmlsection "Files with Multiple Extensions"http://www.acunetix.com/websitesecurity/upload-forms-threat/section "Case 4: Double extensions (part 1)"Test:1. activate export to local server, be sure, that directory is writable:$cfg['SaveDir'] = './';2. select database for test, insert row into table with includedphp code like "<?php phpinfo();?>"3. try to export that database or table, you have now additional option:"Save on server in the directory ./"Confirm that option, let the format be as "SQL"."File name template" change to "@DATABASE () php" and click "Go" button.Server responds with "Dump has been saved to file ./test.php.sql."4. Request created file with webbrowser:http://localhost/PMA/test.php.sqlIn case of success we can see output of phpinfo() function, whichconfirms remote code execution.###############################################################################3. Local File Inclusion in "export.php"###############################################################################Reason: 1. insufficient sanitization of user data before using in include_onceAttack vectors: 1. user-supplied POST parameter "what"Preconditions: 1. logged in as valid PMA user 2. PHP must be < 5.3.4 for null-byte attacks to workPMA security advisory: PMASA-2013-4CVE id: CVE-2013-3240Affected is PMA version 4.0.0-RC2Php script "export.php" line 20:------------------------[ source code start ]----------------------------------foreach ($_POST as $one_post_param => $one_post_value) { $GLOBALS[$one_post_param] = $one_post_value;}PMA_Util::checkParameters(array('what', 'export_type'));// export class instance, not array of properties, as before$export_plugin = PMA_getPlugin( "export", $what, 'libraries/plugins/export/', array( 'export_type' => $export_type, 'single_table' => isset($single_table) ));------------------------[ source code end ]------------------------------------We can see, that user-supplied parameter "what" is used as second argument forthe function PMA_getPlugin(). Let's follow execution flow:Php script "libraries/plugin_interface.lib.php" line 20:------------------------[ source code start ]----------------------------------function PMA_getPlugin( $plugin_type, $plugin_format, $plugins_dir, $plugin_param = false) { $GLOBALS['plugin_param'] = $plugin_param; $class_name = strtoupper($plugin_type[0]) . strtolower(substr($plugin_type, 1)) . strtoupper($plugin_format[0]) . strtolower(substr($plugin_format, 1)); $file = $class_name . ".class.php"; if (is_file($plugins_dir . $file)) { include_once $plugins_dir . $file;------------------------[ source code end ]------------------------------------As seen above, second argument "$plugin_format" is used in variable "$file"and after that in functions is_file() and include_once(). No sanitizationis used against user submitted parameter "what", which leads to directorytraversal and local file inclusion vulnerability. In case of older PHP versionit may be possible to use null byte attack and include arbitrary files on server.###############################################################################4. $GLOBALS array overwrite in "export.php"###############################################################################Reason: 1. insecure POST parameters importing Attack vectors: 1. user-supplied POST parametersPreconditions: 1. logged in as valid PMA userPMA security advisory: PMASA-2013-5CVE id: CVE-2013-3241Affected is PMA version 4.0.0-RC2Php script "export.php" line 20:------------------------[ source code start ]----------------------------------foreach ($_POST as $one_post_param => $one_post_value) { $GLOBALS[$one_post_param] = $one_post_value;}PMA_Util::checkParameters(array('what', 'export_type'));------------------------[ source code end ]------------------------------------We can see, that arbitrary values in $GLOBALS array can be overwritten bysubmitting POST parameters. Such way of input data importing can be consideredas very insecure and in specific situation it is possible to overwrite anyvariable in global scope. This can lead to many ways of exploitation. Below ispresented one of the possibilities.Php script "export.php" line 59:------------------------[ source code start ]----------------------------------$onserver = false;$save_on_server = false;... if ($quick_export) { $onserver = $_REQUEST['quick_export_onserver']; } else { $onserver = $_REQUEST['onserver']; } // Will we save dump on server? $save_on_server = ! empty($cfg['SaveDir']) && $onserver;...// Open file on server if neededif ($save_on_server) { $save_filename = PMA_Util::userDir($cfg['SaveDir']) . preg_replace('@[/\\\\]@', '_', $filename);... if (! $file_handle = @fopen($save_filename, 'w')) { $message = PMA_Message::error(.../* If we saved on server, we have to close file now */ if ($save_on_server) { $write_result = @fwrite($file_handle, $dump_buffer); fclose($file_handle);------------------------[ source code end ]------------------------------------As seen above, when configuration setting "SaveDir" is set, then it is possibleto save database dump to the PMA webserver. By default "SaveDir" is unset andthis prevents possible security problems. As we can overwrite any variables inglobal scope, it is possible to set "SaveDir" to arbitrary value. This willlead to directory traversal vulnerability - attacker is able to save databasedump to any directory in webserver, if only filesystem permissions allow that.Database dump can be with extension ".sql". If attacker can dump databasewith php code and tags in it, this content will be in dump file. If filenameis something like "foobar.php.sql", then by default most Apache webserverinstallations will try to parse this dump file as php file, which can finallylead to the remote code execution vulnerability.Disclosure timeline:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~16.04.2013 -> Sent email to developers16.04.2013 -> First response email from developers16.04.2013 -> Sent detailed information to developers24.04.2013 -> New PMA versions and security advisories released25.04.2013 -> Current advisory releasedContact:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~come2waraxe () yahoo comJanek Vind "waraxe"Waraxe forum: http://www.waraxe.us/forums.htmlPersonal homepage: http://www.janekvind.com/Random project: http://albumnow.com/---------------------------------- [ EOF ] ------------------------------------Sursa: phpMyAdmin 3.5.8 and 4.0.0-RC2 - Multiple Vulnerabilities Quote
