引言
SQL注入是一种常见的网络安全漏洞，它允许攻击者通过在数据库查询中注入恶意SQL代码，从而获取、修改或删除数据库中的数据。本文将深入探讨DVWA（Damn Vulnerable Web Application）中的SQL注入漏洞，提供实战攻略，并发出高危预警。
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。它包含多种安全漏洞，包括SQL注入、XSS、文件上传等，非常适合新手学习和专业人士测试。
SQL注入原理
SQL注入攻击利用了Web应用程序对用户输入的信任，将恶意SQL代码注入到数据库查询中。攻击者通过在输入框中输入特殊构造的SQL语句，可以绕过应用程序的安全机制，直接对数据库进行操作。
DVWA SQL注入实战攻略
1. 确定注入点
首先，需要确定应用程序中哪些输入框可能存在SQL注入漏洞。在DVWA中，登录表单的“用户名”和“密码”字段是常见的注入点。
2. 测试注入点
使用以下SQL注入测试语句进行测试：
- `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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