To solve this machine, we begin by enumerating open ports – finding ports
8065 open. From the main website on port
80, we find a subdomain that reveals a helpdesk. Based on a message we found, we are able to get access to Mattermost, which is hosted on port
8065, after we have a valid
@delivery.htb email address. We are able to exploit the helpdesk to obtain a valid email address, which grants access to Mattermost. From Mattermost, we get a set of credentials, which grants us a shell via SSH – giving access to
user.txt. Next, we dump the Mattermost database to grab password hashes. Based on a message regarding password templates, we are able to bruteforce
root‘s password hash – giving us a shell as root and access to
Like all machines, we begin by enumerating open ports using nmap – finding ports
$ nmap -v -sV -A -p- -oA enum/nmap/tcp-script 10.129.84.144 # Nmap 7.91 scan initiated Sat Jan 16 22:34:02 2021 as: nmap -v -sV -A -p- -oA enum/nmap/tcp-script 10.129.84.144 Nmap scan report for 10.129.84.144 Host is up (0.042s latency). Not shown: 65532 closed ports 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-methods: |_ Supported Methods: GET HEAD |_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, 17 Jan 2021 04:29:27 GMT | X-Frame-Options: SAMEORIGIN | X-Request-Id: mxsmzirdrpr75qa11zsu16szca | X-Version-Id: 220.127.116.11.30.1.57fb31b889bf81d99d8af8176d4bbaaa.false | Date: Sun, 17 Jan 2021 04:38:55 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, 17 Jan 2021 04:38:55 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=1/16%Time=6003BE60%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,\x2017\ SF:x20Jan\x202021\x2004:29:27\x20GMT\r\nX-Frame-Options:\x20SAMEORIGIN\r\n SF:X-Request-Id:\x20mxsmzirdrpr75qa11zsu16szca\r\nX-Version-Id:\x205\.30\. SF:0\.5\.30\.1\.57fb31b889bf81d99d8af8176d4bbaaa\.false\r\nDate:\x20Sun,\x SF:2017\x20Jan\x202021\x2004:38:55\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,\x2017\x20Jan\x202021\x2004:38:55\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:); No exact OS matches for host (If you know what OS is running on it, see https://nmap.org/submit/ ). TCP/IP fingerprint: OS:SCAN(V=7.91%E=4%D=1/16%OT=22%CT=1%CU=31031%PV=Y%DS=2%DC=T%G=Y%TM=6003BEC OS:B%P=x86_64-pc-linux-gnu)SEQ(SP=103%GCD=1%ISR=10C%TI=Z%CI=Z%TS=A)OPS(O1=M OS:54DST11NW7%O2=M54DST11NW7%O3=M54DNNT11NW7%O4=M54DST11NW7%O5=M54DST11NW7% OS:O6=M54DST11)WIN(W1=FE88%W2=FE88%W3=FE88%W4=FE88%W5=FE88%W6=FE88)ECN(R=Y% OS:DF=Y%T=40%W=FAF0%O=M54DNNSNW7%CC=Y%Q=)T1(R=Y%DF=Y%T=40%S=O%A=S+%F=AS%RD= OS:0%Q=)T2(R=N)T3(R=N)T4(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T5(R=Y%DF OS:=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)T6(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O= OS:%RD=0%Q=)T7(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1(R=Y%DF=N%T=40% OS:IPL=164%UN=0%RIPL=G%RID=G%RIPCK=G%RUCK=G%RUD=G)IE(R=Y%DFI=N%T=40%CD=S) Uptime guess: 17.493 days (since Wed Dec 30 10:45:55 2020) Network Distance: 2 hops TCP Sequence Prediction: Difficulty=259 (Good luck!) IP ID Sequence Generation: All zeros Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel TRACEROUTE (using port 993/tcp) HOP RTT ADDRESS 1 41.86 ms 10.10.14.1 2 41.93 ms 10.129.84.144 Read data files from: /usr/bin/../share/nmap OS and Service detection performed. Please report any incorrect results at https://nmap.org/submit/ . # Nmap done at Sat Jan 16 22:36:27 2021 -- 1 IP address (1 host up) scanned in 144.73 seconds
8065 are webservers, so we enumerate them using gobuster and nikto, however, we do not receive any notable information. Going to port
8068 in the browser, we see that it is hosting MatterMost – an open-source, self-hostable online chat service. Going to port
80 in the browser, we are presented with a pretty bare website, that tells us to check out the helpdesk for an account.
80, by clicking the “Contact Us” button, we are presented with a popup that informs us that unregistered users should use the helpdesk to contact the team. It also states that we will get a
@delivery.htb email address, that will allow us access to MatterMost.
When we try to access the HelpDesk from the link, we are forwarded to
helpdesk.delivery.htb. Since we do not have this added to
/etc/hosts, we are unable to access it. After adding it, we are now able to access the helpdesk. Based on the message we previous read, we can assume that opening a ticket will grant us a
@delivery.htb email address, so we open a ticket. After submitting the ticket, we are indeed presented with a valid email.
Using the email address we used to open the ticket, we are able to check the status of the ticket – and receive any responses.
Remembering from the “Contact Us” popup, after we got a valid
@delivery.htb email address, we should be able to gain access to MatterMost. Next, we go to MatterMost on port
8065, to try to get it to verify the account was created. Logging in requires a password, and since we did not set it, we can try to create an account using the
@delivery.htb email address we received. When the ticket was opened, it stated all communications using that email address would be appended to the ticket.
After refreshing the ticket, we do see our MatterMost account was created, and are able to activate it using the link provided.
After logging into MatterMost with our account, we navigate to the “Internal” team. From there, we select the “Internal” channel. Within it, we find a set of credentials. Additionally, we read a comment from
root, that passwords may be some variant of “PleaseSubscribe!”.
Using the credentials, we are able to log into the machine via ssh as the
maildeliverer user – giving access to
Having gained a shell as the
maildeliverer user, we attempt to grab credentials from the ticketing system and MatterMost databases – these may be easy wins for privilege escalation. First, we navigate to
/var/www/osticket/upload/include/ and grab the database credentials from
Unfortunately, this does not provide any advantage. Next, we navigate to
/opt/mattermost/config/ and get the MatterMost database credentials from
config.json. Logging into the database with the credentials, we find an entry for the
Looking at the password hashes, we observe they are in
bcrypt format – denoted by
$2a$. Reflecting on
root‘s message in the MatterMost channel, we may be able to bruteforce the password using “PleaseSubscribe!” as a template. For this, we can use hashcat along with the “best64” rules.
After successfully cracking
root‘s password hash, we attempt to ssh into the machine as
root logon is likely disabled for ssh, we are able to use su from
maildeliverer‘s session to log in as
root. Having done so, we can now read
Thank you for taking the time to read my write-up. I am interested in other ways this machine has been solved. Feel free to reach out to me and we can discuss it. Thanks!