known port assignments and vulnerabilities

Open Port Vulnerabilities List

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. For example, in 2017, cybercriminals spread WannaCry ransomware by exploiting an SMB vulnerability on port 445. Other examples include the ongoing campaigns targeting Microsoft’s Remote Desktop Protocol (RDP) service running on port 3389.

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Read on to learn more about the security risks linked to ports, vulnerable ports that need your attention and ways to enhance the security of open ports.

A Refresher on Ports

Ports are logical constructs that identify a specific type of network service. Each port is linked to a specific protocol, program or service, and has a port number for identification purposes. For instance, secured Hypertext Transfer Protocol (HTTPS) messages always go to port 443 on the server side, while port 1194 is exclusively for OpenVPN.

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. Both TCP and UDP sit at the transport layer of the TCP/IP stack and use the IP protocol to address and route data on the internet. Software and services are designed to use TCP or UDP, depending on their requirements.

TCP and UDP ports are in one of these three states:

• Open — The port responds to connection requests.
• Closed — The port is unreachable, indicating that there is no corresponding service running.
• Filtered — The firewall is monitoring traffic and blocking certain connection requests to the port.

Security Risks Linked to Ports

Numerous incidents have demonstrated that open ports are most vulnerable to attack when the services listening to them are unpatched or insufficiently protected or misconfigured, which can lead to compromised systems and networks. In these cases, threat actors can use open ports to perform various cyberattacks that exploit the lack of authentication mechanisms in the TCP and UDP protocols. One common example is spoofing, where a malicious actor impersonates a system or a service and sends malicious packets, often in combination with IP spoofing and man-in-the-middle-attacks. The campaign against RDP Pipe Plumbing is one of the latest to employ such a tactic. In addition, ports that have been opened on purpose (for instance, on a web server) can be attacked via that port using application-layer attacks such as SQL injection, cross-site request forgery and directory traversal.

Another common technique is the denial of service (DoS) attack, most frequently used in the form of distributed denial of service (DDoS), where attackers send massive numbers of connection requests from various machine to the service on the target in order to deplete its resources.

Vulnerable Ports that Need Your Attention

Any port can be targeted by threat actors, but some are more likely to fall prey to cyberattacks because they commonly have serious shortcomings, such as application vulnerabilities, lack of two-factor authentication and weak credentials.

Here are the most vulnerable ports regularly used in attacks:

Ports 20 and 21 (FTP)

Port 20 and (mainly) port 21 are File Transfer Protocol (FTP) ports that let users send and receive files from servers.

FTP is known for being outdated and insecure. As such, attackers frequently exploit it through:

• Brute-forcing passwords
• Anonymous authentication (it’s possible to log into the FTP port with “anonymous” as the username and password)
• Cross-site scripting
• Directory traversal attacks

Port 22 (SSH)

Port 22 is for Secure Shell (SSH). It’s a TCP port for ensuring secure access to servers. Hackers can exploit port 22 by using leaked SSH keys or brute-forcing credentials.

Port 23 (Telnet)

Port 23 is a TCP protocol that connects users to remote computers. For the most part, Telnet has been superseded by SSH, but it’s still used by some websites. Since it’s outdated and insecure, it’s vulnerable to many attacks, including credential brute-forcing, spoofing and credential sniffing.

Port 25 (SMTP)

Port 25 is a Simple Mail Transfer Protocol (SMTP) port for receiving and sending emails. Without proper configuration and protection, this TCP port is vulnerable to spoofing and spamming.

Port 53 (DNS)

Port 53 is for Domain Name System (DNS). It’s a UDP and TCP port for queries and transfers, respectively. This port is particularly vulnerable to DDoS attacks.

Ports 137 and 139 (NetBIOS over TCP) and 445 (SMB)

Server Message Block (SMB) uses port 445 directly and ports 137 and 139 indirectly. Cybercriminals can exploit these ports through:

• Using the EternalBlue exploit , which takes advantage of SMBv1 vulnerabilities in older versions of Microsoft computers (hackers used EternalBlue on the SMB port to spread WannaCry ransomware in 2017)
• Capturing NTLM hashes
• Brute-forcing SMB login credentials

Ports 80, 443, 8080 and 8443 (HTTP and HTTPS)

HTTP and HTTPS are the hottest protocols on the internet, so they’re often targeted by attackers. They’re especially vulnerable to cross-site scripting, SQL injections, cross-site request forgeries and DDoS attacks.

Ports 1433,1434 and 3306 (Used by Databases)

These are the default ports for SQL Server and MySQL. They are used to distribute malware or are directly attacked in DDoS scenarios. Quite often, attackers probe these ports to find unprotected database with exploitable default configurations.

Port 3389 (Remote Desktop)

This port is used in conjunction with various vulnerabilities in remote desktop protocols and to probe for leaked or weak user authentication. Remote desktop vulnerabilities are currently the most-used attack type; one example is the BlueKeep vulnerability.

Tips for Strengthening the Security of Open Ports

Luckily, there are ways to enhance the security of open ports. We highly recommend the following six strategies:

1. Patch firewalls regularly.

Your firewall is the gatekeeper to all the other systems and services in your network. Patching keeps your firewalls up to date and repairs vulnerabilities and flaws in your firewall system that cybercriminals could use to gain full access to your systems and data.

2. Check ports regularly.

You should also regularly scan and check your ports. There are three  main ways to do this:

• Command-line tools — If you have the time to scan and check ports manually, use command-line tools to spot and scan open ports. Examples include Netstat and Network Mapper, both of which can be installed on a wide range of operating systems, including Windows and Linux.
• Port scanners — If you want faster results, consider using a port scanner. It’s a computer program that checks if ports are open, closed or filtered. The process is simple: The scanner transmits a network request to connect to a specific port and captures the response.
• Vulnerability scanning tools — Solutions of this type can also be used to discover ports that are open or configured with default passwords.
• Track service configuration changes.

Many services on your network connect to various ports, so it is important to monitor the running states of installed services and continuously track changes to service configuration settings. Services can be vulnerable when they are unpatched or misconfigured.

Using Netwrix Change Tracker , you can harden your systems by tracking unauthorized changes and other suspicious activities. In particular, it provides the following functionality:

• Actionable alerting about configuration changes
• Automatic recording, analyzing, validating and verifying of every change
• Real-time change monitoring
• Constant application vulnerability monitoring

4. Use IDP and IPS tools.

Intrusion detection systems (IDS) and intrusion prevention systems (IPS) can help you prevent attackers from exploiting your ports. They monitor your network, spot possible cybersecurity incidents, log information about them and report the incidents to security administrators. IPS complements your firewalls by identifying suspicious incoming traffic and logging and blocking the attack.

5. Use SSH Keys.

Another option is to use SSH keys. These access credentials are more secure than passwords because decrypting SSH is very difficult, if not impossible. There are two types of SSH keys:

• Private or identity keys , which identify users and give them access
• Public or authorized keys , which determine who can access your system

You can use public-key cryptographic algorithms and key generation tools to create SSH keys.

6. Conduct penetration tests and vulnerability assessments.

Consider conducting penetration tests and vulnerability assessments to protect your ports. Although both of these techniques are used to spot vulnerabilities in IT infrastructure, they are quite different. Vulnerability scans only identify and report vulnerabilities, while penetration tests exploit security gaps to determine how attackers can gain unauthorized access to your system.

What is an open port vulnerability?

An open port vulnerability is a security gap caused by an open port. Without proper configuration and protection, attackers can use open ports to access your systems and data.

Which ports are most vulnerable?

Certain ports and their applications are more likely to be targeted because they often have weaker credentials and defenses. Common vulnerable ports include:

• FTP (20, 21)
• Telnet (23)
• NetBIOS over TCP (137, 139)
• HTTP and HTTPS (80, 443, 8080, 8443)
• Ports 1433, 1434 and 3306
• Remote desktop (3389)

Is port 80 a security risk?

Port 80 isn’t inherently a security risk. However, if you leave it open and don’t have the proper configurations in place, attackers can easily use it to access your systems and data. Unlike port 443 (HTTPS), port 80 is unencrypted, making it easy for cybercriminals to access, leak and tamper with sensitive data.

The 8 Most Vulnerable Ports to Check When Pentesting

Pentesting is used by ethical hackers to stage fake cyberattacks. If you're attempting to pentest your network, here are the most vulnerably ports.

Scanning ports is an important part of penetration testing. It allows you to identify and exploit vulnerabilities in websites, mobile applications, or systems. As a penetration tester or ethical hacker, it is essential you know the easiest and most vulnerable ports to attack when carrying out a test.

So what actually are open ports? And which ports are most vulnerable?

What Is a Penetration Test?

A penetration test is a form of ethical hacking that involves carrying out authorized simulated cybersecurity attacks on websites, mobile applications, networks, and systems to discover vulnerabilities on them using cybersecurity strategies and tools. This is done to evaluate the security of the system in question.

What Are Ports?

A port is a virtual array used by computers to communicate with other computers over a network. A port is also referred to as the number assigned to a specific network protocol. A network protocol is a set of rules that determine how devices transmit data to and fro on a network.

The two most common types of network protocols are the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).

Transmission Control Protocols

TCP is a communication standard that allows devices to send and receive information securely and orderly over a network. It does this by establishing a connection from the client computer to the server or designated computer, and then sending packets of information over the network. TCP works hand in hand with the internet protocol to connect computers over the internet.

User Datagram Protocols

UDP works very much like TCP, only it does not establish a connection before transferring information. The UDP is faster than the TCP because it skips the establishing connection step and just transfers information to the target computer over a network. This makes it unreliable and less secure.

How to Check for Open Ports

An open port is a TCP or UDP port that accepts connections or packets of information. If a port rejects connections or packets of information, then it is called a closed port. Open ports are necessary for network traffic across the internet.

To check for open ports, all you need is the target IP address and a port scanner. There are many free port scanners and penetration testing tools that can be used both on the CLI and the GUI. The most popular port scanner is Nmap, which is free, open-source, and easy to use. If you're unfamiliar with it, you can learn how to scan for open ports using Nmap .

Are All Open Ports Vulnerable?

Not necessarily. Although a closed port is less of a vulnerability compared to an open port, not all open ports are vulnerable. Rather, the services and technologies using that port are liable to vulnerabilities. So, if the infrastructure behind a port isn't secure, that port is prone to attack.

Vulnerable Ports to Look Out For

There are over 130,000 TCP and UDP ports, yet some are more vulnerable than others. In penetration testing, these ports are considered low-hanging fruits, i.e. vulnerabilities that are easy to exploit.

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. Port 20 and 21 are solely TCP ports used to allow users to send and to 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 of 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.

An example of an SMB vulnerability is the Wannacry vulnerability that runs on EternalBlue

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 mails. 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 .

Port Scanning as a Pentester

As a penetration tester or ethical hacking, the importance of port scanning cannot be overemphasized. Port scanning helps you to gather information about a given target, know the services running behind specific ports, and the vulnerabilities attached to them.

Now that you know the most vulnerable ports on the internet, you can use this information to perform pentests. Good luck!

Open Connect Vulnerabilities User

Insufficiently protected unlock ports can use your IT environment at significant value. Threat movie often seek to take open interface and theirs applications through spoofing, credential sniffing and other techniques. For example, int 2017, cybercriminals spread WannaCry ransomware by exploiting an SMB vulnerability on port 445. Other examples include the ongoing campaigns targeting Microsoft’s Remote Desktop Protocol (RDP) service running on port 3389.

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Read on to learn more about the security risks linked to ports, vulnerable ports that needs our attention and means to enhance the security of open ports. Ports are virtualization places through einem operating system where network connectivity start and end. Learn how network connectors work both aforementioned most-used port numbers.

A Pick-me-up on Ports

Ports represent logical constructs so identify a specific type of power service. Either port is linked to a specific record, program or maintenance, both got a haven number for identification purposes. Available illustration, secured Hypertext Transfer Protocol (HTTPS) communication always go to left 443 about the server side, while port 1194 is exclusively for OpenVPN. Table 1. Commonly TCP/IP Protocols real Ports ; File Transfer Protocol (FTP). (RFC 959). TCP. 20/21. FTP lives one of of most commonly used file ...

The highest common transport reports this have left numbers are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). TCP has a connection-oriented protocol with built-in re-transmission and flaws recover. UDP is a disconnected protocol that doesn’t recover or corrected errors in messages; it’s faster  and has less lattice overhead traffic than TCP. Both TCP or UDP perch at the convey layer of the TCP/IP stack and use the IP protocol to address and route data on the internet. Software and services are built until use TCP button UDP, depending to their requirements. 50 Common Ports Thee Should Knows - GeeksforGeeks

TCP and UDP ports are included one of these triple states:

• Open — That ports responds to connection requests.
• Closed — The port is unreachable, displayed that there is no associated service operation.
• Filtration — The firewall is monitoring traffic and blocking certain connection requests to the port.

Safety Risks Linked to Ported

Numerous incidents have demonstrated that open ports is most endangered at attack when the services listening to them are unpatched or insufficiently registered or misconfigured, which can maintain to compromised systems and networks. At which cases, threat actors can use free ports to perform various cyberattacks that exploit the lack of authentication machines the one TCP or UDP protocols. One common example is spoofing, where one spiteful actor impersonates ampere system or a assistance and sends viciously packets, frequent within combination with IP spoofing and man-in-the-middle-attacks. The campaign opposes RDP Pipe Plumbing is only in the most to employ such a tactic. In addition, ports that may been opened on purpose (for sample, on a web server) can be attacked via that port using application-layer attacks such as SQL injection, cross-site request forgery and directory traversal. Use this comprehensive common ports cheat sheet to learn about whatever port and several gemein protocols. It also includes a specialty search both copy function.

Another common technique is the denial of service (DoS) attack, of frequently uses in aforementioned form of distributed denial of service (DDoS), where attackers send massive phone of connection requests from various machine to the service on the target in order to decimate its resources.

Weak Ports that Need Your Attention

Any port can be targeted via threat actors, but some are more likely to fall prey to cyberattacks because they commonly will severe shortcomings, such in application vulnerabilities, missing of two-factor authorizations and weak credentials. What is a computer port? | Ports in networking

More are the most vulnerable ports regularly secondhand in strike:

Ports 20 and 21 (FTP)

Connector 20 and (mainly) port 21 are File Transfer Protocol (FTP) terminals that let users send and receipt files from our.

FTP is known since being out-dated and insecure. Because such, offender frequently exploit it through:

• Brute-forcing my
• Anonymous authentication (it’s possible to select into the FTP port with “anonymous” as which username and password)
• Cross-site fisting
• Directory traversal angers

Dock 22 (SSH)

Interface 22 is for Secure Shell (SSH). It’s a TCP port for ensuring secure zugriff to servers. Hackers capacity exploit port 22 by using leaked SSH keys or brute-forcing credentials.

Larboard 23 (Telnet)

Port 23 will ampere TCP protocol that connects users to remote computing. For the most part, Telnet has were superseded by SSH, but it’s yet spent in some websites. Since it’s outdated and insecure, it’s vulnerable to many attackable, including your brute-forcing, spoofing and credential breathe. TCP/IP Ports and Protocols | Pearson A Certification

Port 25 (SMTP)

Haven 25 is a Simple Mail Transfer Protocol (SMTP) port for receiving and submit emails. Without proper configuration and protection, this TCP cable belongs vulnerable the spoofing and spamming. A Computer Science welcome for geeks. It contains well written, well thought plus well explain computer science and programming articles, teasers and practice/competitive programming/company interview Questions.

Haven 53 (DNS)

Port 53 shall for Domain Print System (DNS). It’s a UDP and TCP ports for queries both credit, respectively. This port is particularly vulnerable to DDoS attacks. In this blogpost, we detail aforementioned most fragile connections and provide tips on how till secure them.

Ports 137 and 139 (NetBIOS override TCP) and 445 (SMB)

Server Message Block (SMB) uses port 445 directly and ports 137 plus 139 indirectly. Cybercriminals can exploit these ports through:

• Using the EternalBlue exploit , which takes advantage of SMBv1 sensitive in older release of Microsoft computer (hackers used EternalBlue on the SMB port to dissemination WannaCry ransomware in 2017)
• Captured NTLM hashes
• Brute-forcing SMB login credentials

Ports 80, 443, 8080 plus 8443 (HTTP and HTTPS)

HTTP and HTTPS are the hottest protocols about the internet, hence they’re often targeted by attackers. They’re especially vulnerable for cross-site scripting, SQL injections, cross-site request forgeries and DDoS attacks.

Ports 1433,1434 and 3306 (Used the Databases)

These are the default gates for SQL Server and MySQL. They is used to distribute malware or exist directly attacked with DDoS scenarios. Quite often, attackers probe these attachments to find unprotected database about exploitable default configurations.

Harbor 3389 (Remote Desktop)

This left is used in conjunction with various vulnerabilities in remote desktop protocols and to pen for leaked or weak user user. Remote windows vulnerability are currently an most-used attacked type; one example is the BlueKeep vulnerability.

Tips for Strengthening the Security of Unlock Ports

Luckily, there what ways to optimize the security of open ports. We highly send to following six strategies:

1. Patch firewalls regularly.

Your firewall is the gatekeeper to all the other systems and services in your networking. Patching keeping your firewalls upwards for schedule and repairs vulnerabilities and flaws in your firewall system that cybercriminals could use go gain full admission for your systems and data. 15 Commonly Applied Network Ports Explained

2. Check ports consistently.

Thou must also regularly scan and check your interface. There are three  main ways to do this:

• Command-line tools — If you have the time to scan the check plugs manual, exercise command-line tools to spot and scan open gates. Examples include Netstat or Network Mapper, either of which can be installed on adenine wide range von operating systems, included Windowed and Free.
• Port scanners — If i want faster results, consider using a port scanner. It’s a computer timetable that checks if attachments are open, close or filtered. The process is simply: An body transmits a network request to link to a specifics port and catches the responses.
• Vulnerability study tools — Solve of this type can also be used to discover ports that are open or configured over default passwords.
• Track server configuration changes.

Many services on yours network connect go various ports, so it exists significant on view the running states of installed services plus continuously track changes to service configuration settings. Services can be vulnerable when they are unpatched or misconfigured. (Cheat Sheet - Common Ports)

Using Netwrix Change Tracker , yours able harden your systems by tracking unauthorized modify or other mysterious activities. In particular, information gives the after function:

• Actionable alarm about configuration changes
• Automatic recording, analyzing, validating and verifying from every change
• Real-time change monitoring
• Constantly application vulnerability monitoring

4. Use IDP and IPS tools.

Intrusion detection systems (IDS) additionally intrusion prevention systems (IPS) may assistance you prevent attackers from exploiting your ports. They monitor your network, spot possible cybersecurity emergencies, log information about them and report the incidents in security administrators. IPS complements your firewalls by identifying suspicious incoming traffic and logging furthermore blocking aforementioned offensive. Regular Ports Cheat Sheet: The Ultimate Ports & Protocols List

5. Use SSH Mains.

Another select is to benefit SSH keys. These access credentials live more secure than passwords because decrypting SSH a ultra difficult, if not impossible. There are two types of SSH keys: List of TCP press UDP port numbers - Wikipedia

• Private conversely identity keys , which identify users and give them how
• Public or authorized clue , which determine anyone capacity access your systematisches

You can employ public-key cryptographic algorithms plus press generation useful up creates SSH keys.

6. Conduct penetration tests and vulnerability assessments.

Consider directing penetration trials and attack assessments to preserve your ports. Although both of these technologies are used toward spot vulnerabilities in IT infrastructure, they will fairly different. Vulnerability scans only identify and report vulnerabilities, while penetration tests exploit security gaps to determine how aggressors can gain illegal access to to system.

What be an open port vulnerability?

An open haven vulnerability is a security gap caused by an open port. Without proper configuration and protection, attackers can use open ports to accessible will systems and data.

Whose ports are most vulnerable?

Certain connections or their applications are more likely at remain targeted because they often have weaker credentials and defenses. Common vulnerable ports include: Similarities, many of one official assignments refer to records that were never otherwise are no longer in common usage. This article lists haven numbers plus their ...

• FTP (20, 21)
• Telnet (23)
• NetBIOS via TCP (137, 139)
• HTTP and HTTPS (80, 443, 8080, 8443)
• Connections 1433, 1434 and 3306
• Detached desktop (3389)

Is port 80 ampere security value?

Port 80 isn’t inherently a protection chance. However, if you leave it open also don’t have the proper configurations stylish site, attacks can easily use to to anfahrt your systems and data. Unlike port 443 (HTTPS), port 80 shall unencrypted, making it easy for cybercriminals to access, leak and tamper with sensitive data. SecurityTrails | Upper 200 Most Scanned Network Ports and Report in Cybersecurity

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65% of Port Vulnerabilities Target Just Three Ports

Posted Sep 16, 2019 By: Fortra's Alert Logic

Cybersecurity can be complex and challenging, but—in many ways—it can also be fairly simple if you know what to focus on. For example, there are 65,535 different TCP (Transmission Control Protocol) ports and another 65,535 UDP (User Datagram Protocol) ports—which seems like an overwhelming number of ports to monitor and protect. However, according to research in the Alert Logic Critical Watch Report: SMB Threatscape 2019, 65% of the attacks that target ports focus on just three ports.

Popular TCP Ports for Cyber Attacks

That’s pretty good news. It should be much easier to defend a mere three ports and their vulnerabilities from attacks than it would be to protect more than 130,000 ports, right?

That is true, but there is also a reason attackers tend to target the three ports they do. Most of the ports are unassigned and available for applications and services to use to communicate across the network, but a number of ports are reserved and designated for specific protocols or services. For example, FTP (File Transfer Protocol) uses ports 20 and 21, and SMTP (Simple Mail Transfer Protocol) uses port 25 by default.

Those ports and their vulnerabilities are frequent targets as well, but the three that rank at the top based on research from Alert Logic are ports 22, 80, and 443. Port 22 is SSH (Secure Shell), port 80 is the standard port for HTTP (Hypertext Transfer Protocol) web traffic, and port 443 is HTTPS (Hypertext Transfer Protocol Secure)—the more secure web traffic protocol. What makes these ports juicy targets is that they are public facing by definition—which makes them an attractive target for gaining access to a network. They’re also often used for transmitting sensitive data.

Switching Things Up with a New Port

Most cyber attacks are automated to some extent. Cybercriminals rely on port scanners to scour the internet and identify ports that are exposed to the public internet that could be a viable vector for an attack. Much of cybersecurity is a game of cat-and-mouse as well, though. Attackers pay attention to the trends and techniques used for cybersecurity and develop new tools and strategies to avoid or bypass those defenses.

Alert Logic researchers identified one example of this evolving threat landscape—noting that the recent Microsoft BlueKeep exploits target the fourth most popular port—RDP (Remote Desktop Port) on TCP port 3389.

Alert Logic Critical Watch Report: SMB Threatscape 2019

The report from Alert Logic provides some best practice recommendations to help organizations strengthen their cybersecurity posture:

“As basic guidance, security across all network ports should include defense-in-depth. Ports that are not in use should be closed and organizations should install a firewall on every host as well as monitor and filter port traffic. Regular port scans and penetration testing are also best practices to help ensure there are no unchecked vulnerabilities. In addition to these steps, patch and harden any device, software, or service connected to ports to further close off avenues of attack.”

For more details about how attackers target these popular, public-facing TCP ports, and other key takeaways related to the small and medium business attack surface and how to defend effectively against an expanding threat landscape, check out the complete Alert Logic Critical Watch Report: SMB Threatscape 2019.

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Most Port Vulnerabilities Are Found in Three Ports

Phil Muncaster

UK / EMEA News Reporter , Infosecurity Magazine

• Follow @philmuncaster

The vast majority of vulnerabilities in ports are found in just three, making it theoretically easier for organizations to defend them against attack, according to Alert Logic .

The security vendor analyzed 1.3 petabytes of security data, over 2.8 billion IDS events, 8.2 million verified incidents, and common vulnerabilities for more than 700 SMB customers, in order to compile its Critical Watch Report for 2019.

It claimed that 65% of vulnerabilities it found in Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) ports are linked to SSH (22/TCP), HTTPS (443/TCP) and HTTP (80/TCP).

RDP/TCP comes in fourth place, which is no surprise as it has already been patched several times by Microsoft, including one for the Bluekeep bug which Redmond warned could provide attackers with WannaCry-like “wormable” capabilities.

The number of vulnerabilities in a port is a good indication of its popularity and it’s no surprise that the top three ports for flaws are also ones exposed to the public-facing internet, Alert Logic said.

However, the findings may provide useful intel for security teams in smaller companies to help them reduce their attack surface quickly and easily.

“As basic guidance, security across all network ports should include defense-in-depth. Ports that are not in use should be closed and organizations should install a firewall on every host as well as monitor and filter port traffic,” the report advised .

“Regular port scans and penetration testing are also best practices to help ensure there are no unchecked vulnerabilities.”

Alert Logic also urged IT security teams to patch and harden any device, software or service connected to ports and to tackle any new vulnerabilities as they appear, as well as changing all default setting and passwords and running regular configuration checks.

The report found that most unpatched vulnerabilities in the SMB space are over a year old, and that misconfigurations, weak encryption and unsupported Windows versions also represent serious risks.

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CISA Adds Three Known Exploited Vulnerabilities to Catalog

CISA has added three new vulnerabilities to its  Known Exploited Vulnerabilities Catalog , based on evidence of active exploitation.

• CVE-2023-36584  Microsoft Windows Mark of the Web (MOTW) Security Feature Bypass Vulnerability
• CVE-2023-1671  Sophos Web Appliance Command Injection Vulnerability
• CVE-2020-2551  Oracle Fusion Middleware Unspecified Vulnerability

These types of vulnerabilities are frequent attack vectors for malicious cyber actors and pose significant risks to the federal enterprise.  Note:  To view other newly added vulnerabilities in the catalog, click on the arrow in the "Date Added to Catalog" column—which will sort by descending dates.

Binding Operational Directive (BOD) 22-01: Reducing the Significant Risk of Known Exploited Vulnerabilities  established the Known Exploited Vulnerabilities Catalog as a living list of known Common Vulnerabilities and Exposures (CVEs) that carry significant risk to the federal enterprise. BOD 22-01 requires Federal Civilian Executive Branch (FCEB) agencies to remediate identified vulnerabilities by the due date to protect FCEB networks against active threats. See the   BOD 22-01 Fact Sheet  for more information.

Although BOD 22-01 only applies to FCEB agencies, CISA strongly urges all organizations to reduce their exposure to cyberattacks by prioritizing timely remediation of  Catalog vulnerabilities  as part of their vulnerability management practice. CISA will continue to add vulnerabilities to the catalog that meet the  specified criteria .

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Related Advisories

Cisa adds two known exploited vulnerabilities to catalog, cisa releases four industrial control systems advisories, cisa releases first secure by design alert.

Common Ports Cheat Sheet: The Ultimate Ports & Protocols List

Perhaps you’re angsty that you’ve forgotten what a certain port number meant. Rest assured, you don’t have to remember all 65,535 port numbers. With so much information to remember, it’s understandable if you forget a common port. That’s why we put together this cheat sheet of common network ports for you.

A crucial domain of expertise in IT-related certifications such as Cisco Certified Network Associate (CCNA) and those of CompTIA is port numbers and associated services , which this common ports and protocols cheat sheet covers. If you want to remember a port number or protocol, this cheat sheet will help everyone, from students to professionals.

Get a copy of this common ports cheat sheet here to keep on your desk. When you're ready, scroll below to find the port you’re looking for.

Common Ports Cheat Sheet Search

Search our Common Ports cheat sheet to find the right cheat for the term you're looking for. Simply enter the term in the search bar and you'll receive the matching cheats available.

Common Ports and Protocols Cheat Sheet

The following tables cover services (and malware) that use common TCP ports and some UDP or SCTP ports.

Well-known/System Ports: 0 – 1023

Registered ports: 1024 – 49151, dynamic/private ports: 49152 – 65535.

You may use these ports for custom applications free from concerns that it may clash with existing processes.

The Most Common Ports for Exams

If you’re studying for IT certifications such as CCNA , focus on these ports:

We hope that you found this cheat sheet useful. Familiarity with ports and protocols is vital to building secure applications and troubleshooting problems on computer networks. Whether you're studying or working, this cheat sheet of common network ports will help you in academic and professional settings.

For further resources, or if you’re curious about how ports and protocols fit into cyber security, look into network security courses available with our StationX Accelerator Program .

Frequently Asked Questions

FTP: ports 20-21; SSH/SCP: port 22; HTTP: 80; HTTPS: 443; POP3: 110; POP3 over SSL: 995; IMAP: 143; IMAP over SSL: 993. We recommend you download the graphic in Well-known/System Ports .

It depends on whether you’re referring to system ports (1024) or want to include ports registered with apps (49152) because system ports range from 0 through 1023, and registered ports span 1024 – 49151.

FTP: ports 20-21; SSH/SCP: port 22; Telnet: 23; SMTP: 25; DNS: 53; HTTP: 80; POP3: 110; IMAP: 143; HTTPS: 443.

FTP: port 21; SSH/SCP: 22; Telnet: 23; SMTP: 25; DNS: 53; POP3: 110; IMAP: 145; HTTP: 80; HTTPS: 443; MySQL: 3306; RDP: 3389; VNC: 5900.

The following are the three types of ports with corresponding port number ranges: • Well-known/System ports: 0 – 1023 • Registered ports: 1024 – 49151 • Dynamic/Private ports: 49152 – 65535

Level Up in Cyber Security: Join Our Membership Today!

Nathan House is the founder and CEO of StationX. He has over 25 years of experience in cyber security, where he has advised some of the largest companies in the world. Nathan is the author of the popular "The Complete Cyber Security Course", which has been taken by over half a million students in 195 countries. He is the winner of the AI "Cyber Security Educator of the Year 2020" award and finalist for Influencer of the year 2022.

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Nathan, thank you for supplying this sheet. It comes in handy when you’re trying to remember what a particular port is used by.

Our pleasure.

Thank you, Nathan

This is a great single point to reference all default ports. Thank you!!!

Very good, it will be in front of me!

Ports on computers are required for networking, and without them, the computer would be completely isolated and it would be unable to communicate with other devices. So thank you for proving this list of the Common TCP and UDP Port numbers.

After resetting my router cause the password got changed and all the setting were changed to gain access to my computer. I spent about 20 minutes setting up the router. It appears the router never got set up from the cable company when it was installed. So if you have not done so lately check your router and settings.

Cool, Thanks for sharing!!

Sorry Nathan, i did not leave a comment for this “Common Ports” Chart last-week. I am glad i signed up to your news letter you are a good researcher. thank you for sharing with us all..

Nathan, I must thank you for these cheat sheets! They’ve been great on my learning and certification journey!

Thank you too!

Really really useful.Thanks a lot!!

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Top Contributors in Windows 10: Ramesh Srinivasan  -  questions_  -  neilpzz  -  Horace Wiggins  -  _AW_ 👏

November 15, 2023

Top Contributors in Windows 10:

Ramesh Srinivasan  -  questions_  -  neilpzz  -  Horace Wiggins  -  _AW_ 👏

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Windows Vulnerable Ports Exposed

Hello there, 

I recently conducted a few vulnerability tests regarding my windows 10 computer and noticed that there were a few open ports. Those ports are as follows,

I got the above results by conducting a nmap scan.

As far as I know, port 135 and port 139 pertaining to NetBios are vulnerable. And port 445 which is for  Windows File Sharing is vulnerable as well. 

Hence my concern is that, is there a way to close these open ports and please let me know why these ports were opened (is it due to malware)

A quick response is highly appreciated in this regard.

Thanks and regards

Report abuse

Ports 135, 139, and 445 are all NetBIOS related and it is not unusual for them to be open locally.  They 

are generally not open publicly  (and shouldn't be).  I would not advise blocking them on your local network. 

re. wsdapi this is a quoted from  wikepedia -

"Web Services for Devices or Web Services on Devices (WSD) is a Microsoft API to enable programming

 connections to web service enabled devices, such as printers, scanners and file shares."

In all likelihood there is no need for concern.  (For example on my PC I see the netbios ports listening 

locally but blocked externally, which is the usual status.

You can test external acess   using https://www.yougetsignal.com/tools/open-ports/

You might also be intersted in the Nirsoft CurPorts utility which gives a nicer view than netstat 

http://www.nirsoft.net/utils/cports.html

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Related ports: 5986  

« back to SG Ports

External Resources SANS Internet Storm Center: port 5985

Notes: Port numbers in computer networking represent communication endpoints. Ports are unsigned 16-bit integers (0-65535) that identify a specific process, or network service. IANA is responsible for internet protocol resources, including the registration of commonly used port numbers for well-known internet services. Well Known Ports: 0 through 1023. Registered Ports: 1024 through 49151. Dynamic/Private : 49152 through 65535. TCP ports use the Transmission Control Protocol, the most commonly used protocol on the Internet and any TCP/IP network. TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and that packets will be delivered in the same order in which they were sent. Guaranteed communication/delivery is the key difference between TCP and UDP. UDP ports use the Datagram Protocol. Like TCP, UDP is used in combination with IP (the Internet Protocol) and facilitates the transmission of datagrams from one computer to applications on another computer, but unlike TCP, UDP is connectionless and does not guarantee reliable communication; it's up to the application that received the message to process any errors and verify correct delivery. UDP is often used with time-sensitive applications, such as audio/video streaming and realtime gaming, where dropping some packets is preferable to waiting for delayed data. When troubleshooting unknown open ports, it is useful to find exactly what services/processes are listening to them. This can be accomplished in both Windows command prompt and Linux variants using the "netstat -aon" command. We also recommend runnig multiple anti-virus/anti-malware scans to rule out the possibility of active malicious software. For more detailed and personalized help please use our forums.

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