Firewall evasion techniques are methods that attackers use to bypass firewalls and gain unauthorized access to networks and systems. Firewalls are security devices that are used to filter network traffic and prevent unauthorized access.

There are a number of different firewall evasion techniques, but some of the most common include:

Spoofing is a technique in which an attacker sends traffic with a false source IP address. This can be used to bypass firewalls that are configured to block traffic from certain IP addresses.

One example of this is IP spoofing, where an attacker can modify the source address of a packet to make it appear as though it came from a different location. This can be done using various tools, such as Nmap, which allows users to scan networks and send packets with spoofed source IP addresses.

The steps to perform IP spoofing using Nmap include:

1. Identify the target network and the IP address to be spoofed
2. Launch Nmap and enter the IP address to be spoofed as the source address for the scan
3. Begin scanning the target network using Nmap

This can be used to bypass firewalls and other security measures that rely on IP address filtering.

Once the IP address to be spoofed has been identified, the attacker can use Nmap, to launch the attack. The following steps outline the process of using Nmap for IP spoofing:

Open the terminal and launch Nmap by typing the following command:

sudo nmap

Enter the IP address of the target system to be scanned, along with any additional options or parameters as needed. For example, the following command would scan the target system using a TCP SYN scan with verbose output:

sudo nmap -sS -v target_ip_address

Use the --spoof option followed by the IP address to be spoofed to set the source address for the scan. For example, the following command would spoof the source address to be 192.168.1.100:

sudo nmap -sS -v --spoof=192.168.1.100 target_ip_address

Press Enter to launch the scan. Nmap will send packets to the target system with the spoofed source IP address, tricking the system into thinking that the traffic is coming from a trusted source.

Fragmentation is a common technique used by attackers to bypass firewall security measures. The process involves breaking a large packet of data into smaller fragments, making it more difficult for firewalls to identify and block the data. Attackers can use this technique to sneak malware, viruses, or other malicious payloads past firewalls that are configured to block large packets of data.

To launch a fragmentation attack, an attacker would need to use specialized tools such as the Scapy packet manipulation tool or the Hping3 network tool. The attacker would need to first identify the target and the firewall protecting it. They would then craft specially designed packets that are designed to evade the firewall and deliver the payload to the target.

For example, an attacker could use Scapy to create a series of packets that are designed to bypass a firewall that is configured to block packets larger than a certain size. By fragmenting the data into smaller packets, the attacker can bypass the firewall’s filters and deliver their payload to the target.

Tunneling is a technique often used by attackers to bypass firewalls and network security controls. This involves encapsulating one type of network traffic inside another type of network traffic, thereby making it difficult to detect or block the original traffic. For instance, an attacker could use tunneling to send unauthorized data or instructions across a network that is protected by a firewall.

One example of a tunneling attack is an HTTP tunneling attack, where an attacker encapsulates other protocols, such as SSH or Telnet, inside HTTP packets. This allows the attacker to bypass firewalls that are configured to block SSH or Telnet traffic, as the firewall sees only HTTP traffic.

Another example is a DNS tunneling attack, where an attacker encapsulates other protocols inside DNS queries or responses. This allows the attacker to bypass firewalls that are configured to block non-DNS traffic.

To launch a successful tunneling attack, an attacker typically requires tools such as proxy servers, VPNs, or custom software that can create and manage the tunnels. For example, an attacker may use tools like ProxyCap, Bitvise SSH Client, or OpenVPN to create encrypted tunnels that can be used to bypass network security controls.

DNS rebinding is a complex and potentially devastating attack technique used by hackers to bypass firewalls and redirect traffic to malicious websites. Attackers use DNS rebinding to change the IP address of a domain name to a malicious one, which can then be used to exploit vulnerabilities in web applications or steal sensitive information from users.

To illustrate how a DNS rebinding attack can be launched, let’s consider an example. Suppose an attacker wants to steal a victim’s login credentials for a banking website. The attacker creates a fake login page that is hosted on their own server. They then configure their DNS server to resolve the domain name of the banking website to the IP address of their own server.

The attacker then sends an email to the victim, containing a link to a legitimate banking website. When the victim clicks the link, their browser sends a request to the DNS server to resolve the domain name of the banking website. The DNS server returns the IP address of the attacker’s server, which the victim’s browser uses to connect to the fake login page.

When the victim enters their login credentials on the fake login page, the attacker’s code captures the credentials and sends them to the attacker’s server. The attacker can then use the stolen credentials to log in to the victim’s account and carry out further malicious actions.

To launch a DNS rebinding attack, an attacker needs to have control over a DNS server and a web server that can host malicious code. Tools such as Rebind and T50 can be used to automate the process of setting up the DNS server and launching the attack. As a countermeasure, organizations can configure their firewalls to block traffic to known malicious domains or use DNS security solutions to detect and block DNS rebinding attacks.

Web application vulnerabilities can be a major threat to organizations, as they can be used by attackers to bypass firewalls and gain unauthorized access to networks and systems. Among the most common web application, vulnerabilities are SQL injection, cross-site scripting (XSS), and directory traversal.

To launch successful attacks, attackers can use a variety of tools such as SQLMap, XSStrike, and DirBuster. SQLMap, for instance, is a powerful tool that automates the process of detecting and exploiting SQL injection vulnerabilities. This tool can be used to identify the type of database being used, dump data from databases, and even gain command-line access to the server. Similarly, XSStrike is a tool that can be used to detect and exploit cross-site scripting vulnerabilities by automatically detecting inputs that are vulnerable to XSS attacks and generating payloads to exploit them.

DirBuster is another popular tool that can be used to brute force directories and files on web servers. It works by generating a list of common directories and file names and then testing them against the webserver to see which ones are accessible. Attackers can then use this information to gain access to sensitive data or carry out other malicious actions.

These tools can be used in combination with other techniques such as social engineering to launch effective attacks on web applications. For example, an attacker may use social engineering to gain access to a system administrator’s credentials and then use SQLMap to exploit SQL injection vulnerabilities and gain further access to the network.

Firewall evasion techniques can be used by attackers to bypass a variety of different firewalls, including:

• Personal firewalls: Personal firewalls are firewalls that are installed on individual computers.
• Network firewalls: Network firewalls are firewalls that are installed on network devices, such as routers and switches.
• Web application firewalls (WAFs): WAFs are firewalls that are specifically designed to protect web applications from attack.

It is important to be aware of firewall evasion techniques so that you can take steps to protect your networks and systems from attack. Some of the steps that you can take to protect your networks and systems from firewall evasion include:

• Keep your firewalls up to date: Firewalls are constantly being updated with new features and security patches. It is important to keep your firewalls up to date so that they can protect you from the latest threats.
• Use a variety of security controls: No single security control can provide complete protection. It is important to use a variety of security controls, such as firewalls, intrusion detection systems (IDSs), and intrusion prevention systems (IPSs), to protect your networks and systems from attack.
• Educate your users: Users are often the weakest link in the security chain. It is important to educate your users about security best practices so that they can help to protect your networks and systems from attack.