DVWA——SQL Injection通关记录（Medium）

Security Level：Medium

1.判断注入点及注入类型

这一等级明显加上了一些限制，用户无法在页面上直接输入，而是限制进行数字的选择

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这时就考虑抓包，看看能否在数据包中进行注入语句的构造

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找到了id=1这一句，是数字型，看看是不是注入点

右键点击发送至Repeater

构造语句

id=1 and 1=2

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可以查询，确定是数字型

用字符型验证一下，构造语句

1’ and 1=1#

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出错了，结尾的注释符其实可要可不要，Submit=Submit意思就是提交，默认也是这个值

再来看是否存在注入，构造语句

1 or 1=1#

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好，此处存在数字型注入

2.获取账号和密码

步骤与Low等级完全相同，最后构造的语句为

1 union select user,password from users #

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再把口令解密成明文，结束

8.源码分析

点击右下角View Source

SQL Injection Source
vulnerabilities/sqli/source/medium.php
<?php
if( isset( $_POST[ 'Submit' ] ) ) {
    // Get input
    $id = $_POST[ 'id' ];
    $id = mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $id);
    $query  = "SELECT first_name, last_name FROM users WHERE user_id = $id;";
    $result = mysqli_query($GLOBALS["___mysqli_ston"], $query) or die( '<pre>' . mysqli_error($GLOBALS["___mysqli_ston"]) . '</pre>' );
    // Get results
    while( $row = mysqli_fetch_assoc( $result ) ) {
        // Display values
        $first = $row["first_name"];
        $last  = $row["last_name"];
        // Feedback for end user
        echo "<pre>ID: {$id}<br />First name: {$first}<br />Surname: {$last}</pre>";
    }
}
// This is used later on in the index.php page
// Setting it here so we can close the database connection in here like in the rest of the source scripts
$query  = "SELECT COUNT(*) FROM users;";
$result = mysqli_query($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>' );
$number_of_rows = mysqli_fetch_row( $result )[0];
mysqli_close($GLOBALS["___mysqli_ston"]);
?>