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Java Filter过滤XSS注入非法参数

程序员文章站 2024-02-08 17:35:22
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  XSS又称CSS,全称Cross SiteScript,跨站脚本攻击,是Web程序中常见的漏洞,XSS属于被动式且用于客户端的攻击方式,所以容易被忽略其危害性。其原理是攻击者向有XSS漏洞的网站中输入(传入)恶意的HTML代码,当其它用户浏览该网站时,这段HTML代码会自动执行,从而达到攻击的目的。如,盗取用户Cookie、破坏页面结构、重定向到其它网站等。

  web.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
	http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<filter>
	   <filter-name>ParametersFilter</filter-name>
	   <filter-class>com.aiTech.filter.ParametersFilter</filter-class>
	</filter>
<filter-mapping>
     	<filter-name>ParametersFilter</filter-name>
     	<url-pattern>/web/*</url-pattern>
	</filter-mapping>
</web-app>

  过滤器代码:


import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public final class RequestWrapper extends HttpServletRequestWrapper
{
  public RequestWrapper(HttpServletRequest servletRequest)
  {
    super(servletRequest);
  }

  public String[] getParameterValues(String parameter)
  {
    String[] values = super.getParameterValues(parameter);
    if (values == null) {
      return null;
    }
    int count = values.length;
    String[] encodedValues = new String[count];
    for (int i = 0; i < count; i++) {
      encodedValues[i] = cleanXSS(values[i]);
    }
    return encodedValues;
  }

  public String getParameter(String parameter) {
    String value;
    try {
      value = super.getParameter(parameter);
    }
    catch (Exception e)
    {
      value = "";
    }
    if (value == null) {
      return null;
    }

    return cleanXSS(value);
  }

  public String getHeader(String name) {
    String value = super.getHeader(name);
    if (value == null)
      return null;
    return cleanXSS(value);
  }

  private String cleanXSS(String value)
  {
    value = value.replaceAll("/\\*(.|[\\r\\n])*?\\*/", "");
    value = value.replaceAll("<", "<").replaceAll(">", ">");
    value = value.replaceAll("\\(", "(").replaceAll("\\)", ")");
    value = value.replaceAll("'", "'").replaceAll("\"", """);
    value = value.replaceAll("(?i)eval", "");
    value = value.replaceAll("(?i)javascript", "");
    value = value.replaceAll("(?i)expression", "");

    value = value.replaceAll("(?i)script", "");
    return value;
  }
}