【DVWA】存储型XSS

1.low级别

<?php if( isset( $_POST[ 'btnSign' ] ) ) { // Get input $message = trim( $_POST[ 'mtxMessage' ] ); $name = trim( $_POST[ 'txtName' ] ); // Sanitize message input $message = stripslashes( $message ); $message = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $message ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); // Sanitize name input $name = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $name ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); // Update database $query = "INSERT INTO guestbook ( comment, name ) VALUES ( '$message', '$name' );"; $result = mysqli_query($GLOBALS["___mysqli_ston"], $query ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' ); //mysql_close(); } ?>

分析： 没有过滤

解： 2.medium级别

<?php if( isset( $_POST[ 'btnSign' ] ) ) { // Get input $message = trim( $_POST[ 'mtxMessage' ] ); $name = trim( $_POST[ 'txtName' ] ); // Sanitize message input $message = strip_tags( addslashes( $message ) ); $message = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $message ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); $message = htmlspecialchars( $message ); // Sanitize name input $name = str_replace( '<script>', '', $name ); $name = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $name ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); // Update database $query = "INSERT INTO guestbook ( comment, name ) VALUES ( '$message', '$name' );"; $result = mysqli_query($GLOBALS["___mysqli_ston"], $query ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' ); //mysql_close(); } ?>

分析： htmlspecialchars() 函数把预定义的字符转换为 HTML 实体。 str_replace() 函数以其他字符替换字符串中的一些字符（区分大小写）。 下面的输入框会被转义，上面的输入框会替换

解： 先改一下输入框的可输入长度，再写入js代码 3.high级别

<?php if( isset( $_POST[ 'btnSign' ] ) ) { // Get input $message = trim( $_POST[ 'mtxMessage' ] ); $name = trim( $_POST[ 'txtName' ] ); // Sanitize message input $message = strip_tags( addslashes( $message ) ); $message = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $message ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); $message = htmlspecialchars( $message ); // Sanitize name input $name = preg_replace( '/<(.*)s(.*)c(.*)r(.*)i(.*)p(.*)t/i', '', $name ); $name = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $name ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); // Update database $query = "INSERT INTO guestbook ( comment, name ) VALUES ( '$message', '$name' );"; $result = mysqli_query($GLOBALS["___mysqli_ston"], $query ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' ); //mysql_close(); } ?>

分析： preg_replace 函数执行一个正则表达式的搜索和替换。

解： 4.impossible级别

<?php if( isset( $_POST[ 'btnSign' ] ) ) { // Check Anti-CSRF token checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' ); // Get input $message = trim( $_POST[ 'mtxMessage' ] ); $name = trim( $_POST[ 'txtName' ] ); // Sanitize message input $message = stripslashes( $message ); $message = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $message ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); $message = htmlspecialchars( $message ); // Sanitize name input $name = stripslashes( $name ); $name = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $name ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : "")); $name = htmlspecialchars( $name ); // Update database $data = $db->prepare( 'INSERT INTO guestbook ( comment, name ) VALUES ( :message, :name );' ); $data->bindParam( ':message', $message, PDO::PARAM_STR ); $data->bindParam( ':name', $name, PDO::PARAM_STR ); $data->execute(); } // Generate Anti-CSRF token generateSessionToken(); ?>

分析： htmlspecialchars() 函数把预定义的字符转换为 HTML 实体。