Most vulnerable ports in networking security

Most vulnerable ports in networking security for cybersecurity engineers while pentesting. Insufficiently protected open ports can put your IT environment at serious risk. Threat actors often seek to exploit open ports and their applications through spoofing, credential sniffing, and other techniques. Similar post: How to Learn Ethical Hacking in Nigeria.

Most vulnerable ports every hacker should know in 2022. Pentesting is used by ethical hackers to stage fake cyberattacks. If you’re attempting to pentest your network, here are the most vulnerable ports. Regardless of being a red or blue security expert, knowing which are the most commonly hacked ports can save you precious time in scanning and securing those ports or identifying potential port vulnerabilities in a system.

What Are Ports in computer networking? A port is a virtual array used by computers to communicate with other computers over a network. The two most common types of network protocols are the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).

The most common transport protocols that have port numbers are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). TCP is a connection-oriented protocol with built-in re-transmission and error recovery. UDP is a connectionless protocol that doesn’t recover or correct errors in messages; it’s faster and has less network overhead traffic than TCP.

What are the most vulnerable ports every hacker should know? Below are some common port numbers and their uses in cybersecurity.

Port NumberProtocolPort Service / Reasons for the attack
21TCPFile Transfer Protocol (FTP). / To remotely gain access to the target machine’s files.
22TCPSecure Shell (SSH). / To establish a connection to the target machine.
23TCPTelnet. / To be able to control network devices.
25TCPSimple Mail Transfer Protocol (SMTP) / To disrupt or intercept email services.
53TCP and UDPDomain Name System (DNS). / To disrupt the services or operations of specific organizations.
80TCPHypertext Transport Protocol (HTTP). / The modern internet has largely moved away from insecure HTTP but there are still companies that use this.
443TCPHypertext Transport Protocol (HTTP) and HTTP over TLS/SSL (HTTPS). / Despite being more secure than port 80, companies secured by 443 are where the money is.
110TCPPost Office Protocol version 3 (POP3) / To disrupt or intercept email services.
135TCP and UDPWindows Remote Procedure Call (RPC). / Unsecured 135s allow hackers to issue remote commands to vulnerable computers.
137-139TCP and UDPNETBIOS over TCP/IP / provides access to shared resources
1433-1434TCP and UDPMicrosoft SQL Server. / Thanks to SQL Server’s popularity, the target base is huge, and hacking these ports can cause maximum profit or damage.

Many ports have known vulnerabilities that you can exploit when they come up in the scanning phase of your penetration test. Here are some common vulnerable ports you need to know.

1. FTP (20, 21)

FTP stands for File Transfer Protocol. Ports 20 and 21 are solely TCP ports used to allow users to send and receive files from a server to their personal computers.

The FTP port is insecure and outdated and can be exploited using:

  • Anonymous authentication. You can log into the FTP port with both username and password set to “anonymous”.
  • Cross-Site Scripting.
  • Brute-forcing passwords.
  • Directory traversal attacks.

2. SSH (22)

SSH stands for Secure Shell. It is a TCP port used to ensure secure remote access to servers. You can exploit the SSH port by brute-forcing SSH credentials or using a private key to gain access to the target system.

3. SMB (139, 137, 445)

SMB stands for Server Message Block. It is a communication protocol created by Microsoft to provide sharing access to files and printers across a network. When enumerating the SMB port, find the SMB version, and then you can search for an exploit on the internet, Searchsploit, or Metasploit.

The SMB port could be exploited using the EternalBlue vulnerability, brute forcing SMB login credentials, exploiting the SMB port using NTLM Capture, and connecting to SMB using PSexec.

4. DNS (53)

DNS stands for Domain Name System. It is both a TCP and UDP port used for transfers and queries respectively. One common exploit on the DNS ports is the Distributed Denial of Service (DDoS) attack.

5. HTTP / HTTPS (443, 80, 8080, 8443)

HTTP stands for HyperText Transfer Protocol, while HTTPS stands for HyperText Transfer Protocol Secure (which is the more secure version of HTTP). These are the most popular and widely used protocols on the internet, and as such are prone to many vulnerabilities. They are vulnerable to SQL injections, cross-site scripting, cross-site request forgery, etc

6. Telnet (23)

The Telnet protocol is a TCP protocol that enables a user to connect to remote computers over the internet. The Telnet port has long been replaced by SSH, but it is still used by some websites today. It is outdated, insecure, and vulnerable to malware. Telnet is vulnerable to spoofing, credential sniffing, and credential brute-forcing.

7. SMTP (25)

SMTP stands for Simple Mail Transfer Protocol. It is a TCP port used for sending and receiving mail. It can be vulnerable to mail spamming and spoofing if not well-secured.

8. TFTP (69)

TFTP stands for Trivial File Transfer Protocol. It’s a UDP port used to send and receive files between a user and a server over a network. TFTP is a simplified version of the file transfer protocol. Because it is a UDP port, it does not require authentication, which makes it faster yet less secure.

It can be exploited using password spraying and unauthorized access, and Denial of Service (DoS) attacks.

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