引言
命令注入漏洞是网络安全中常见的一种漏洞类型，它允许攻击者通过在应用程序中插入恶意命令来执行未经授权的操作。本文将以DVWA（Damn Vulnerable Web Application）为例，深入浅出地解析低级别命令注入漏洞，并揭秘其源码实现。
DVWA简介
DVWA是一款专门用于网络安全学习和测试的Web应用程序。它内置了多种漏洞，包括命令注入、SQL注入、XSS等，可以帮助安全研究人员和开发者了解和防范这些漏洞。
命令注入漏洞原理
命令注入漏洞发生在应用程序没有正确地验证用户输入，并将这些输入用于执行系统命令时。攻击者可以通过构造特殊的输入，欺骗应用程序执行恶意命令，从而获取系统权限或执行其他非法操作。
低级别命令注入漏洞解析
1. 漏洞环境搭建
首先，我们需要搭建一个DVWA环境。可以从以下链接下载DVWA：DVWA下载链接
2. 漏洞复现
在DVWA中，选择“Low”安全级别，然后访问“SQL Injection”模块。在这个模块中，我们可以看到以下表单：
<form action="sql.php?page=1" method="post">
<label for="id">ID:</label>
<input type="text" name="id" id="id" value="" />
<input type="submit" value="Submit" />
</form>
3. 构造恶意输入
在“ID”输入框中，我们尝试构造以下恶意输入：
”`html 1’ UNION SELECT null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, 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