Java防止跨站脚本（XSS）注入攻击

转自：http://www.what21.com/programming/java/javaweb-summary/xss3.html

Java防止跨站脚本（XSS）注入攻击

前边既说明了XSS攻击的危害性，也通过模拟案例了解了XSS攻击原理，这里就介绍一下如何防御XSS攻击。 采用Filter技术，对所有参数都进行过滤，处理方案为： 1. 含有html标签做转义。 2. 含有敏感的html脚本，直接处理掉。  XSS Filter源码：

package com.what21.filter.xss;

import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.Map;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

public class XSSFilter implements Filter {

    // XSS处理Map
    private static Map<String,String> xssMap = new LinkedHashMap<String,String>();

    public void init(FilterConfig filterConfig) throws ServletException {
        // 含有脚本： script
        xssMap.put( "[s|S][c|C][r|R][i|C][p|P][t|T]" , "" );
        // 含有脚本 javascript
        xssMap.put( "[\\\"\\\'][\\s]*[j|J][a|A][v|V][a|A][s|S][c|C][r|R][i|I][p|P][t|T]:(.*)[\\\"\\\']" , "\"\"" );
        // 含有函数： eval
        xssMap.put( "[e|E][v|V][a|A][l|L]\\((.*)\\)" , "" );
        // 含有符号 <
        xssMap.put( "<" , "&lt;" );
        // 含有符号 >
        xssMap.put( ">" , "&gt;" );
        // 含有符号 (
        xssMap.put( "\\(" , "(" );
        // 含有符号 )
        xssMap.put( "\\)" , ")" );
        // 含有符号 '
        xssMap.put( "'" , "'" );
        // 含有符号 "
        xssMap.put( "\"" , "" ");
    }

    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        // 强制类型转换 HttpServletRequest
        HttpServletRequest httpReq = (HttpServletRequest)request;
        // 构造HttpRequestWrapper对象处理XSS
        HttpRequestWrapper httpReqWarp = new HttpRequestWrapper(httpReq,xssMap);
        //
        chain.doFilter(httpReqWarp, response);

    }

    public void destroy() {

    }
}

package com.what21.filter.xss;

import java.util.Map;
import java.util.Set;

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

public final class HttpRequestWrapper extends HttpServletRequestWrapper {

    private Map<String, String> xssMap;

    public HttpRequestWrapper(HttpServletRequest request) {
        super (request);
    }

    public HttpRequestWrapper(HttpServletRequest request,
            Map<String, String> xssMap) {
        super (request);
        this .xssMap = xssMap;
    }

    @Override
    public String[] getParameterValues(String parameter) {
        String[] values = super .getParameterValues(parameter);
        if (values == null ) {
            return null ;
        }
        int count = values.length;
        // 遍历每一个参数，检查是否含有
        String[] encodedValues = new String[count];
        for ( int i = 0 ; i < count; i++) {
            encodedValues[i] = cleanXSS(values[i]);
        }
        return encodedValues;
    }

    @Override
    public String getParameter(String parameter) {
        String value = super .getParameter(parameter);
        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);

    }

    /**
     * 清除恶意的XSS脚本
     *
     * @param value
     * @return
     */
    private String cleanXSS(String value) {
        Set<String> keySet = xssMap.keySet();
        for (String key : keySet){
            String v = xssMap.get(key);
            value = value.replaceAll(key,v);
        }
        return value;
    }
}

<filter>
    <filter-name>XSSFilter</filter-name>
    <filter- class >com.what21.filter.xss.XSSFilter</filter- class >
</filter>
<filter-mapping>
    <filter-name>XSSFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>