Introduction

BoardLight, an easy-rated machine on Hack The Box created by cY83rR0H1t, involves discovering a new virtual host, leveraging a CVE to gain a low-privileged foothold, performing horizontal escalation to another user on the box, and ultimately exploiting a lesser-known binary for root access.

Let's get right to it.

Enumeration

As always, we started by running an initial Nmap scan to discover open ports and the services associated with them. There were two services running: SSH and HTTP.

# Nmap 7.94SVN scan initiated Sun Jun  9 16:38:28 2024 as: nmap -sC -sV -oN boardlight-initial 10.10.11.11
Nmap scan report for 10.10.11.11
Host is up, received echo-reply ttl 63 (0.052s latency).
Scanned at 2024-06-09 16:38:28 EDT for 12s
Not shown: 957 closed tcp ports (reset)
PORT      STATE    SERVICE            REASON         VERSION
22/tcp    open     ssh                syn-ack ttl 63 OpenSSH 8.2p1 Ubuntu 4ubuntu0.11 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   3072 06:2d:3b:85:10:59:ff:73:66:27:7f:0e:ae:03:ea:f4 (RSA)
| ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQDH0dV4gtJNo8ixEEBDxhUId6Pc/8iNLX16+zpUCIgmxxl5TivDMLg2JvXorp4F2r8ci44CESUlnMHRSYNtlLttiIZHpTML7ktFHbNexvOAJqE1lIlQlGjWBU1hWq6Y6n1tuUANOd5U+Yc0/h53gKu5nXTQTy1c9CLbQfaYvFjnzrR3NQ6Hw7ih5u3mEjJngP+Sq+dpzUcnFe1BekvBPrxdAJwN6w+MSpGFyQSAkUthrOE4JRnpa6jSsTjXODDjioNkp2NLkKa73Yc2DHk3evNUXfa+P8oWFBk8ZXSHFyeOoNkcqkPCrkevB71NdFtn3Fd/Ar07co0ygw90Vb2q34cu1Jo/1oPV1UFsvcwaKJuxBKozH+VA0F9hyriPKjsvTRCbkFjweLxCib5phagHu6K5KEYC+VmWbCUnWyvYZauJ1/t5xQqqi9UWssRjbE1mI0Krq2Zb97qnONhzcclAPVpvEVdCCcl0rYZjQt6VI1PzHha56JepZCFCNvX3FVxYzEk=
|   256 59:03:dc:52:87:3a:35:99:34:44:74:33:78:31:35:fb (ECDSA)
| ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBK7G5PgPkbp1awVqM5uOpMJ/xVrNirmwIT21bMG/+jihUY8rOXxSbidRfC9KgvSDC4flMsPZUrWziSuBDJAra5g=
|   256 ab:13:38:e4:3e:e0:24:b4:69:38:a9:63:82:38:dd:f4 (ED25519)
|_ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAILHj/lr3X40pR3k9+uYJk4oSjdULCK0DlOxbiL66ZRWg
80/tcp    open     http               syn-ack ttl 63 Apache httpd 2.4.41 ((Ubuntu))
|_http-title: Site doesn't have a title (text/html; charset=UTF-8).
| http-methods: 
|_  Supported Methods: GET HEAD POST OPTIONS
|_http-server-header: Apache/2.4.41 (Ubuntu)

22 - SSH

22/tcp    open     ssh                syn-ack ttl 63 OpenSSH 8.2p1 Ubuntu 4ubuntu0.11 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   3072 06:2d:3b:85:10:59:ff:73:66:27:7f:0e:ae:03:ea:f4 (RSA)
| ssh-rsa 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
|   256 59:03:dc:52:87:3a:35:99:34:44:74:33:78:31:35:fb (ECDSA)
| ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBK7G5PgPkbp1awVqM5uOpMJ/xVrNirmwIT21bMG/+jihUY8rOXxSbidRfC9KgvSDC4flMsPZUrWziSuBDJAra5g=
|   256 ab:13:38:e4:3e:e0:24:b4:69:38:a9:63:82:38:dd:f4 (ED25519)
|_ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAILHj/lr3X40pR3k9+uYJk4oSjdULCK0DlOxbiL66ZRWg

As always, SSH is most likely not going to be our way in unless we already have credentials or a key. I will skip this for the time being.

80 - HTTP

80/tcp    open     http               syn-ack ttl 63 Apache httpd 2.4.41 ((Ubuntu))
|_http-title: Site doesn't have a title (text/html; charset=UTF-8).
| http-methods: 
|_  Supported Methods: GET HEAD POST OPTIONS
|_http-server-header: Apache/2.4.41 (Ubuntu)

Nmap does not return a whole lot of information for this port. Let's just check it out.