这段代码接受来自用户的受感染数据，检查要打印的字符只有字母和数字字符以及空格符，以此来提供安全保护。

This piece of code takes up tainted data from the user, ensuring protection as it checks that the characters to be printed are only alphanumeric characters and Spaces.

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用户不需要去点击或下载任何东西，单单浏览受感染的网站就可以受到攻击。

Users do not have to click or download anything to become infected, merely visiting an infected website is sufficient.

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该攻击和大多数基于web的攻击类似，均为哄骗不知情的用户访问受感染的恶意网站或被非法操纵的合法网站。

The attack begins like most Web-based infections: an unsuspecting user visits an infected Website — either a malicious or rigged legitimate one.

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