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Vulnerabilities by Common Ports

by Steve Tilson
April 11, 2017

Commonly used ports can be easy targets for attackers, based on the vulnerabilities associated with those ports.  Many common services are tied to these ports such as DNS, HTTP, SMB, and SMTP.  This dashboard leverages a variety of active and passive port filters in multiple ways to display vulnerability information for common ports. As hosts are discovered, SecurityCenter Continuous View (CV) enumerates vulnerabilities and their associated TCP/UDP ports. During active scanning, SecurityCenter CV uses Nessus to perform SYN, TCP, and other types of port scanning. Using passive scanning, SecurityCenter CV is able to ascertain the server side transmissions as well as the client side. Transmission picked up using passive scanning are active services utilizing those ports. By combining active and passive port scanning, analysts can have a clear view of the port usage across the network. 

Some services discovered by SecurityCenter CV may be the result of misconfigurations or rogue software/hardware assets. Some are just default services running from set up. The components of this dashboard identify common services by TCP and UDP ports and display vulnerability information in multiple ways. Indicators of vulnerabilities by severity level are shown for the top common ports, as well as the number of hosts with vulnerabilities on a specific port. Port vulnerabilities are also displayed by Common Vulnerability Scoring System (CVSS) score.

This dashboard identifies vulnerabilities associated with commonly used ports, providing administrators the ability to quickly identify and mitigate risks due to unnecessary services. Analysts can identify vulnerabilities by severity, assisting with the prioritization of risk mitigations through the patch management process or other mitigation techniques. Information provided by this dashboard can be used to recommend changes to firewall policies in order to restrict access to common ports that are not required and further secure the network. 

This dashboard is available in the SecurityCenter Feed, a comprehensive collection of dashboards, reports, Assurance Report Cards, and assets. The dashboard can be easily located in the SecurityCenter Feed under the category Threat Detection & Vulnerability Assessments. The dashboard requirements are:

  • SecurityCenter 5.4.2
  • Nessus 6.10.1
  • PVS 5.2.0

Tenable SecurityCenter Continuous View (CV) provides continuous network monitoring, vulnerability identification, and security monitoring. SecurityCenter CV is continuously updated with information about advanced threats, zero-day vulnerabilities, and new types of regulatory compliance configuration audit files. Tenable constantly analyzes information from our unique sensors, delivering continuous visibility and critical context, enabling decisive action that transforms a security program from reactive to proactive. Active scanning examines the applications on the systems, running processes and services, detection of web applications, configuration settings, and additional vulnerabilities. Agent scanning enables scanning and detection of vulnerabilities on transient and isolated devices. Passive listening provides real-time discovery of vulnerabilities on operating systems, protocols, network services, wireless devices, web applications, and critical infrastructure. With this information, analysts have greater insight on port vulnerabilities within the network. Tenable enables powerful, yet non-disruptive, continuous monitoring of the organization to ensure vulnerability information is available to analysts.

Listed below are more detailed descriptions of each of the components.

Vulnerability Reporting by Common Ports - Severity Levels by Common Port: This component effectively uses color and empty space to convey information about vulnerabilities and risk severity. Each column is a severity level of low, medium, high, or critical. Each row is a common popular port chosen at random. Using this matrix as a template, a security administrator can modify the matrix to use assets, IP addresses, plugin families, repositories, and more. The icon colors can communicate risk: green for low severity, yellow for medium, and red for high severity. For the critical severities, the red icon with white “X” is used. When no match is found, the default setting is an empty display text field.

Vulnerability Reporting by Common Ports - Counting Hosts by Common Ports: This component contains six columns that enumerate the number of hosts with vulnerabilities on a specific port. The columns provide a count of vulnerable hosts based on a specific ports and severity level. The last column provides a percentage of hosts with an exploitable vulnerability on that port. The colors used in this matrix have a transparent background and change the color based on the severity level. The color green represents low severities, yellow is for medium severity, high severity vulnerabilities are orange, and critical severities are red. The last column in purple shows exploitability but makes no reference to severity level.

Vulnerability Reporting by Common Ports - Port and Protocol: This matrix component provides a count of vulnerabilities by severity level, TCP port, and vulnerability type. The first two rows use active detection, while the bottom two use passive detection. For each detection method, there is a row for TCP and UDP. Port ranges from 0-1024, along with severity levels of low, medium, high, and critical, are used for each column. The last column provides a percentage of exploitable vulnerabilities. The raw results are displayed based on the severity level. The colors used are green (low), yellow (medium), orange (high), and red (critical). The last column in purple shows exploitability but makes no reference to severity level.

Vulnerability Reporting by Common Ports - CVSS Vulnerability Counts Per Port: This matrix uses a combination of CVSS scores and severity to communicate the risk of discovered vulnerabilities. There are seven rows, each one for CVSS level starting with 4.0 and ending with 10. Next, there are eight columns with port filters for less than 1024, greater than 1024 and unique filters for FTP, SSH, SMTP, HTTP and HTTPS. Through a severity filter of low, medium, high, and critical, this ensures informational severity levels are not part of the vulnerability count. The colors used are yellow (medium), orange (high), and red (critical). 

Vulnerability Reporting by Common Ports - Percentage of Vulnerabilities Based on CVSS and Port: This matrix uses a combination of CVSS scores and severity to communicate the risk of discovered vulnerabilities and displays the percentage of vulnerabilities with a specific CVSS score of total vulnerabilities. There are seven rows, each one for CVSS level starting with 4.0 and ending with 10. Next, there are eight columns with port filters for less than 1024, greater than 1024 and unique filters for FTP, SSH, SMTP, HTTP and HTTPS. Through a severity filter of low, medium, high, and critical, this ensures informational severity levels are not part of the vulnerability count. The colors used are yellow (medium), orange (high), and red (critical). Please note that if the less than 1% of the total vulnerabilities match the respective filter, than 0% will be displayed.