XSS概述
跨站脚本攻击(Cross Site Scripting),缩写为XSS。恶意攻击者往Web页面里插入恶意Script代码,当用户浏览该页之时,嵌入其中Web里面的Script代码会被执行,从而达到恶意攻击用户的目的。
Servlet的方式
1、继承HttpServletRequestWrapper,实现对请求参数的过滤
/*** xss请求适配器*/
public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {public XssHttpServletRequestWrapper(HttpServletRequest request) {super(request);}/*** 对数组参数进行特殊字符过滤*/@Overridepublic String[] getParameterValues(String name) {String[] values = super.getParameterValues(name);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;}/*** 对参数中特殊字符进行过滤*/@Overridepublic String getParameter(String name) {String value = super.getParameter(name);if (value == null) {return null;}return cleanXSS(value);}/*** 获取attribute,特殊字符过滤*/@Overridepublic Object getAttribute(String name) {Object value = super.getAttribute(name);if (value != null && value instanceof String) {cleanXSS((String) value);}return value;}/*** 对请求头部进行特殊字符过滤*/@Overridepublic String getHeader(String name) {String value = super.getHeader(name);if (value == null) {return null;}return cleanXSS(value);}/*** 转义字符,使用该方法存在一定的弊端* * @param value* @return*/private String cleanXSS2(String value) {// 移除特殊标签value = value.replaceAll("<", "<").replaceAll(">", ">");value = value.replaceAll("\\(", "(").replaceAll("\\)", ")");value = value.replaceAll("'", "'");value = value.replaceAll("eval\\((.*)\\)", "");value = value.replaceAll("[\\\"\\\'][\\s]*javascript:(.*)[\\\"\\\']", "\"\"");value = value.replaceAll("script", "");return value;}private String cleanXSS(String value) {if (value != null) {//推荐使用ESAPI库来避免脚本攻击,value = ESAPI.encoder().canonicalize(value);// 避免空字符串value = value.replaceAll(" ", "");// 避免script 标签Pattern scriptPattern = Pattern.compile("<script>(.*?)</script>", Pattern.CASE_INSENSITIVE);value = scriptPattern.matcher(value).replaceAll("");// 避免src形式的表达式scriptPattern = Pattern.compile("src[\r\n]*=[\r\n]*\\\'(.*?)\\\'",Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);value = scriptPattern.matcher(value).replaceAll("");scriptPattern = Pattern.compile("src[\r\n]*=[\r\n]*\\\"(.*?)\\\"",Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);value = scriptPattern.matcher(value).replaceAll("");// 删除单个的 </script> 标签scriptPattern = Pattern.compile("</script>", Pattern.CASE_INSENSITIVE);value = scriptPattern.matcher(value).replaceAll("");// 删除单个的<script ...> 标签scriptPattern = Pattern.compile("<script(.*?)>",Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);value = scriptPattern.matcher(value).replaceAll("");// 避免 eval(...) 形式表达式scriptPattern = Pattern.compile("eval\\((.*?)\\)",Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);value = scriptPattern.matcher(value).replaceAll("");// 避免 e-xpression(...) 表达式scriptPattern = Pattern.compile("e-xpression\\((.*?)\\)",Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);value = scriptPattern.matcher(value).replaceAll("");// 避免 javascript: 表达式scriptPattern = Pattern.compile("javascript:", Pattern.CASE_INSENSITIVE);value = scriptPattern.matcher(value).replaceAll("");// 避免 vbscript:表达式scriptPattern = Pattern.compile("vbscript:", Pattern.CASE_INSENSITIVE);value = scriptPattern.matcher(value).replaceAll("");// 避免 οnlοad= 表达式scriptPattern = Pattern.compile("onload(.*?)=",Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);value = scriptPattern.matcher(value).replaceAll("");}return value;}}
2、实现Filter,实现XSS过滤器
/*** xss过滤器*/
public class XssFilter implements Filter {FilterConfig filterConfig = null;@Overridepublic void init(FilterConfig filterConfig) throws ServletException {this.filterConfig = filterConfig;}@Overridepublic void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)throws IOException, ServletException {//对请求进行拦截,防xss处理chain.doFilter(new XssHttpServletRequestWrapper((HttpServletRequest) request), response);}@Overridepublic void destroy() {this.filterConfig = null;}
}
3、注入XSS过滤器,两种方式
第一种方式:配置web.xml
<!-- xss过滤器 -->
<filter><filter-name>XssSqlFilter</filter-name><filter-class>cn.aric.xss.XssFilter</filter-class>
</filter>
<filter-mapping><filter-name>XssSqlFilter</filter-name><url-pattern>/*</url-pattern><dispatcher>REQUEST</dispatcher><dispatcher>FORWARD</dispatcher>
</filter-mapping>1234567891011
第二种方式:注解
/*** 注入Xss过滤器(注解方式)*/
public class WebInitializer implements WebApplicationInitializer{@Overridepublic void onStartup(ServletContext servletContext) throws ServletException {//添加监听器servletContext.addListener(RequestContextListener.class);//添加过滤器Dynamic xssFilterRegistration = servletContext.addFilter("XssFilter", XssFilter.class);//添加映射规则xssFilterRegistration.addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST,DispatcherType.FORWARD,DispatcherType.INCLUDE), false, "/*");}}
Spring整合的方式
1、使用spring的HtmlUtils,可以使用StringEscapeUtils 中的过滤方法
/*** 解决XSS跨站脚本攻击和sql注入攻击,使用spring的HtmlUtils,可以使用StringEscapeUtils 中的过滤方法*/
public class XssSpringHttpServletRequestWrapper extends HttpServletRequestWrapper{public XssSpringHttpServletRequestWrapper(HttpServletRequest request) {super(request);}/*** 对数组参数进行特殊字符过滤*/@Overridepublic String[] getParameterValues(String name) {String[] values = super.getParameterValues(name);String[] newValues = new String[values.length];for (int i = 0; i < values.length; i++) {//spring的HtmlUtils进行转义newValues[i] = HtmlUtils.htmlEscape(values[i]);}return newValues;}/*** 拦截参数,并对其进行字符转义*/@Overridepublic String getParameter(String name) {return HtmlUtils.htmlEscape(name);}/*** 拦截参数,并对其进行字符转义*/@Overridepublic Object getAttribute(String name) {return HtmlUtils.htmlEscape(name);}}
2、实现XSS过滤器
/*** spring方式xss过滤器*/
public class XssSpringFilter implements Filter{@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}@Overridepublic void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)throws IOException, ServletException {HttpServletRequest req = (HttpServletRequest) request;chain.doFilter(new XssSpringHttpServletRequestWrapper(req), response);}@Overridepublic void destroy() {}
3、配置XSS过滤器
<!-- spring方式的xss过滤器 -->
<filter><filter-name>xssSpringFilter</filter-name><filter-class>cn.aric.xss.XssSpringHttpServletRequestWrapper</filter-class>
</filter>
<filter-mapping><filter-name>xssSpringFilter</filter-name><url-pattern>/*</url-pattern>
</filter-mapping>123456789