OSCPsx PetsC: Davidson Walkthrough & Exploitation

by Jhon Lennon 50 views

Hey guys! Today, we're diving deep into the world of ethical hacking with a walkthrough of the OSCPsx PetsC machine, Davidson. This box is a fantastic learning opportunity for those pursuing their OSCP (Offensive Security Certified Professional) certification or anyone looking to sharpen their penetration testing skills. We'll cover everything from initial reconnaissance to gaining root access, so buckle up and get ready to learn!

Reconnaissance: Gathering Intel Like a Pro

Reconnaissance is the cornerstone of any successful penetration test. It's where we gather crucial information about our target, Davidson, without directly engaging it in a potentially noisy or detectable way. Think of it as digital reconnaissance – we're observing, mapping, and understanding the terrain before making our move. This phase involves using various tools and techniques to identify open ports, running services, potential vulnerabilities, and other valuable data points. Let's start with the basics: an nmap scan.

We'll use nmap to scan the target machine for open ports and services. The following command performs a comprehensive scan:

nmap -sC -sV -p- -oA davidson 10.10.10.XXX

Here's a breakdown of the nmap flags used:

  • -sC: Runs default scripts to gather more information about the services running on the open ports.
  • -sV: Attempts to determine the service versions running on the open ports.
  • -p-: Scans all 65535 ports. This is a comprehensive scan to ensure no service is missed.
  • -oA davidson: Saves the scan results in three different formats (normal, XML, and grepable) with the base name "davidson".
  • 10.10.10.XXX: The IP address of the target machine (replace with the actual IP).

After running the nmap scan, carefully examine the output. Look for the following:

  • Open Ports: Which ports are open? Common ports like 21 (FTP), 22 (SSH), 80 (HTTP), 139 & 445 (SMB), and 3389 (RDP) can indicate potential entry points. Less common ports might reveal custom applications or services.
  • Running Services: What services are running on those open ports? Knowing the specific service (e.g., Apache httpd 2.4.18, OpenSSH 7.2p2) allows you to search for known vulnerabilities.
  • Version Numbers: Precise version numbers are gold. Search for known exploits for those specific versions using resources like Exploit-DB or Metasploit.

For example, if nmap reveals that port 80 is open and running Apache httpd 2.4.18, you'd want to search for "Apache httpd 2.4.18 vulnerabilities" to see if any public exploits exist. Carefully analyze the nmap output and document everything. Note any interesting services, version numbers, and potential vulnerabilities. This information will guide your next steps in the exploitation process.

Exploitation: From Initial Foothold to User Access

Once you have gathered enough information during the reconnaissance phase, the next step is to exploit any vulnerabilities you've uncovered. This involves using various techniques and tools to gain an initial foothold on the target system. Let's assume, for the sake of this walkthrough, that our nmap scan revealed a vulnerable service running on the Davidson machine – perhaps an outdated version of a web server with a known exploit. Let’s consider a scenario where we find an outdated version of Apache running, say, Apache 2.4.29 with a known vulnerability like remote code execution (RCE). The specific exploit we use will depend on the vulnerabilities identified during the reconnaissance phase. Popular resources like Exploit-DB (https://www.exploit-db.com/) and Metasploit (https://www.metasploit.com/) can provide the necessary exploits.

  • Finding the Right Exploit: Using search terms like "Apache 2.4.29 RCE exploit" on Exploit-DB will reveal available exploits. Carefully review the exploit details, including the affected versions, the vulnerability description, and any available code or scripts.

  • Using Metasploit: Metasploit is a powerful framework for penetration testing. It includes a vast library of exploits and tools for automating the exploitation process. If a Metasploit module exists for the identified vulnerability, you can use it to gain a shell on the target system. For example, to use a Metasploit module, you would launch Metasploit with msfconsole, search for the relevant module, configure the options (like the target IP address and port), and then run the exploit. Example commands:

    msfconsole
search apache 2.4.29 rce
use exploit/unix/http/apache_mod_cgi_rce #Replace with the correct module
set RHOST 10.10.10.XXX
set RPORT 80
exploit

  • Manual Exploitation: If a Metasploit module is not available, you might need to manually exploit the vulnerability using a custom script or code. This requires a deeper understanding of the vulnerability and how to exploit it. This may involve crafting malicious payloads, sending specially crafted requests, or exploiting a specific flaw in the application's code.

If the exploit is successful, you should obtain a shell on the target system. This shell might be a low-privilege shell, meaning you are running as a regular user with limited access. The type of shell you get (e.g., www-data, apache, or a similar user) will depend on the exploited service. Before moving on, stabilize your shell. Unstable shells can be frustrating, disconnecting unexpectedly and losing your progress. Use commands like `python -c 'import pty; pty.spawn([