XSS : 跨站脚本攻击(Cross Site Scripting),为不和层叠样式表(Cascading Style Sheets, CSS)的缩写混淆,故将跨站脚本攻击缩写为XSS。恶意攻击者往Web页面里插入恶意html代码,当用户浏览该页之时,嵌入其中Web里面的html代码会被执行,从而达到恶意攻击用户的特殊目的。

过滤方式:主要通过对html标签进行转义的方式达到过滤的目的

過濾器配置

@Configuration
public class FilterConfig
{
    @Value("${xss.enabled}")
    private String enabled;

    @Value("${xss.excludes}")
    private String excludes;

    @Value("${xss.urlPatterns}")
    private String urlPatterns;

    @SuppressWarnings({ "rawtypes", "unchecked" })
    @Bean
    public FilterRegistrationBean xssFilterRegistration()
    {
        FilterRegistrationBean registration = new FilterRegistrationBean();
        registration.setDispatcherTypes(DispatcherType.REQUEST);
        registration.setFilter(new XssFilter());
        registration.addUrlPatterns(StringUtils.split(urlPatterns, ","));
        registration.setName("xssFilter");
        registration.setOrder(Integer.MAX_VALUE);
        Map<String, String> initParameters = Maps.newHashMap();
        initParameters.put("excludes", excludes);
        initParameters.put("enabled", enabled);
        registration.setInitParameters(initParameters);
        return registration;
    }
}

自定義過濾器編寫

public class XssFilter implements Filter
{
    /**
     * 排除链接
     */
    public List<String> excludes = new ArrayList<>();

    /**
     * xss过滤开关
     */
    public boolean enabled = false;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException
    {
        String tempExcludes = filterConfig.getInitParameter("excludes");
        String tempEnabled = filterConfig.getInitParameter("enabled");
        if (StringUtils.isNotEmpty(tempExcludes))
        {
            String[] url = tempExcludes.split(",");
            for (int i = 0; url != null && i < url.length; i++)
            {
                excludes.add(url[i]);
            }
        }
        if (StringUtils.isNotEmpty(tempEnabled))
        {
            enabled = Boolean.valueOf(tempEnabled);
        }
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException
    {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse resp = (HttpServletResponse) response;
        if (handleExcludeURL(req, resp))
        {
            chain.doFilter(request, response);
            return;
        }
        XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper((HttpServletRequest) request);
        chain.doFilter(xssRequest, response);
    }

    private boolean handleExcludeURL(HttpServletRequest request, HttpServletResponse response)
    {
        if (!enabled)
        {
            return true;
        }
        if (excludes == null || excludes.isEmpty())
        {
            return false;
        }
        String url = request.getServletPath();
        for (String pattern : excludes)
        {
            Pattern p = Pattern.compile("^" + pattern);
            Matcher m = p.matcher(url);
            if (m.find())
            {
                return true;
            }
        }
        return false;
    }

過濾處理實現

public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper
{
    /**
     * @param request
     */
    public XssHttpServletRequestWrapper(HttpServletRequest request)
    {
        super(request);
    }

    @Override
    public String[] getParameterValues(String name)
    {
        String[] values = super.getParameterValues(name);
        if (values != null)
        {
            int length = values.length;
            String[] escapseValues = new String[length];
            for (int i = 0; i < length; i++)
            {
                // 防xss攻击和过滤前后空格
                escapseValues[i] = EscapeUtil.clean(values[i]).trim();
            }
            return escapseValues;
        }
        return super.getParameterValues(name);
    }
}

一个好奇的人