How to Easily Run a Vulnerability Scan Using Nmap

Nmap (network mapper) can be used for vulnerability scanning to identify known vulnerabilities. While Nmap is not primarily a vulnerability scanner, Nmap’s scripts can help cybersecurity experts perform scans for safety.

Nmap vulnerability scanning gathers data about a target host, system, or network, tests it for vulnerabilities, and reports on any vulnerabilities that are found within a company’s infrastructure. 

To learn more about vulnerability scans: Why Vulnerability Scanning is Important

How Nmap Vulnerability Scanning Works

Nmap vulnerability scanning is the process of using Nmap to scan for and identify known vulnerabilities. 

Nmap vulnerability scanning is the use of Nmap tools to identify and scan any vulnerabilities in a company’s infrastructure. Nmap is not only used for vulnerability scanning, but it is an effective tool for cybersecurity experts.

Nmap vulnerability scanning focuses on gathering information about a company’s infrastructure, system, and network information to test for vulnerabilities and any weaknesses it may contain. These vulnerabilities will be reported to the business as well.

The effectiveness of a company’s IT security policy can also be determined by Nmap vulnerability scanning.

With fast-moving changes in technology, cyberattacks can be a problem throughout all industries. It is important to have cybersecurity methods in place, especially a Nmap vulnerability scanning tool. 

For more information, also see: Why Firewalls are Important for Network Security

Installing Nmap

Installing Nmap is slightly different depending on the platform. See below for Windows, Mac OS, and Linux Distributions:

Installing Nmap on Windows

  1. The first step of installing Nmap is to find the stable version of Nmap and select download.
  2. Next, find the location where the file is downloaded. Often for Windows, it will go into the “Downloads” folder. The file will start with “Nmap-XXX-setup.” If a user is unable to find the file, they can do a quick search in “Downloads.” The file should be labeled as EXE (executable). A user will have to run it with administrator privileges. The user needs to right-click the file and then click “run as administrator.”
  3. The installer is now able to run. A pop-up will appear and ask the user to accept the end-user agreement. Click “I Agree.”
  4. After the installer starts, it will ask the user what parts of Nmap they want to install. Usually, every component will be selected and installed by default. Unless a company does not need a component, experts recommend letting all components download.
  5. Then the installer will ask where a company wants to install Nmap. It defaults to program files, but a company is also able to move it. This is an option that allows a company to know exactly where the Nmap is. 
  6. Click “Install,” and Nmap will install the Nmap. Usually, it is a quick process.
  7. Then the Nmap will give confirmation it has been installed.

Installing Nmap on Mac OS X

  1. First, download the file labeled nmap-[version].dmg. Double-click the icon to open it.
  2. After selecting the icon, disk image content images will likely appear. One of the files will be a Mac meta-package file. This file will be labeled as nmap-[version].mpkg. Open the file to initiate the installer.
  3. If a pop-up opens on the screen, a user must right-click or control-click on the .mpkg and select “Open.”
  4. Follow the instructions in the installer. The user will be asked for the company’s password since Nmap is installed in a company’s system directory.
  5. As soon as the installation is complete, eject the disk image by control-clicking on its icon and selecting “Eject.” Now the image can be moved into the trash.

Installing Nmap on Linux Distributions

  1. Download the latest version of Nmap in .tar.bz2 (bzip2 compression) or .tgz (gzip compression) format.
  2. Decompress the downloaded tarball with commands that look similar to bzip2 -cd nmap-[VERSION].tar.bz2 | tar xvf. The easier command is written as tar xvjf nmap-[VERSION].tar.bz2. If a user downloads the .tgz version, replace bzip2 with gzip in the decompression command.
  3. Change into the new directory: cd nmap-[VERSION]
  4. Next, configure the build system: ./configure
  5. If the configuration is successful, an ASCII art dragon appears to congratulate you on the successful configuration.
  6. Then a user should build Nmap: make. A user should note that GNU Make is required.
  7. A user should then become a privileged user for system-wide install: su root
  8. Install Nmap, support files, docs, etc.: make install. It should now be installed on a user’s computer as /usr/local/bin/nmap.

For more information on Linux Distribution steps, go to the Linux Instructions page.

Using Vulnerability Scanning Nmap Scripts

There are multiple steps to successfully use Nmap vulnerability scans. Companies can choose to create a target host or network to specifically be scanned.

Here are the steps to using a vulnerability scanning Nmap script:

Install Nmap

Directions for each type of Nmap are listed above. To download, go to the Nmap download page

Decide what Host or Network needs to be Scanned

A company gets the option to choose what hosts or networks they would like to scan. Giving a system the IP address or hostname to scan will give the vulnerability scanning Nmap a target to focus on. This prepares the company to continue.

Nmap has many built-in scripts that will be used for vulnerability scanning. If the company uses Linux systems it will likely be located in their “/usr/share/nmap/scripts/.” If the company uses Windows, it will likely be located under “C:\Program Files (x86)\Nmap\scripts.” The script should be chosen based on the vulnerability a user is scanning.

To specify a target, use the following commands:

  • iL: <inputfilename>: Input from list of hosts/networks
  • iR: <num hosts>: Choose random targets
  • Exclude <host1>[,<host2>]… : Exclude hosts/networks
  • Excludefile: <exclude_file>: Exclude list from file

Run the Nmap Vulnerability Scan

When it comes to vulnerability scanning with Nmap, there are multiple commands for scanning including Vuln, Vulscan, and Nmap-vulners. See their commands based on a Linux system:

  • Vuln: The vuln script is already part of the Nmap. To use it, type:

Nmap –script vuln [target host or IP address goes here]

  • Vulscan: To use the Vulscan vulnerability scan, type:

nmap -sV –script=vulscan/vulscan.nse [target host or IP address goes here]

  • Nmap-vulners: To use the Nmap-vulners vulnerability scanning script, type:

nmap –script nmap-vulners/ -sV [target host or IP address goes here]

Once the Nmap vulnerability scan is complete, users will be given information about the vulnerabilities to protect against harmful errors.

To learn more about Nmap: The Network Mapping Market

Detecting Nmap Scans on Your Network

Likely, a company who uses cybersecurity tools such as SIEM tools and firewalls will receive alerts from these tools. Nmap vulnerability scans usually will log the information from the scan, which would also alert the company.

Nmap scans should spot irregular activity, so cybercriminals will not find the vulnerabilities they can exploit. A Nmap scan report could allow hackers to see weaknesses in a company’s infrastructure.

However, a report might not be enough to detect scans. Different tools can also produce error warnings, which can be an indicator of an intrusive scan. Company administrators should always check their system logs for irregularities in case there is an intrusive scan.

For more information, also see: Data Security Trends

Bottom Line: Nmap Vulnerability Scanning

Nmap vulnerability scanning is used to check the effectiveness of a company’s security policy, gather information about a target host, system, or network. The scan tests for vulnerabilities, and gives a company the ability to notify and respond to security threats and violations. 

Nmap has been a popular tool on its own, but with the ability to use vulnerability scanning tools, Nmap is an truly effective cybersecurity tool.

To learn more about types of vulnerability scanners: 3 Types of Vulnerability Scanners Explained

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