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Exercise 2: Scanning with SuperScan

Description

There are many port scanners available to administrators today. A very powerful connection-based TCP scanner is SuperScan. This tool has several features that are not present in some commercial products.

SuperScan has the capability to perform ping and port scans using a valid IP address. If you have a predetermined list of IP addresses that need to be scanned, you can have SuperScan read in a prewritten text file. In many situations it can severely impact network performance if the administrator is scanning a large number of addresses. With this in mind, you have the ability to throttle the amount of bandwidth that SuperScan utilizes.

Trojans and other backdoor applications are very difficult to locate on systems. These applications communicate with the outside world by trying to hide themselves in a high-numbered TCP or UDP port. By performing regular port scans of your environment and by having an accurate baseline, you will be able to quickly determine if an unknown port is present.

Having a firewall in place is not enough to properly protect your external devices. Allowing only the needed ports into your network is crucial for maintaining a secure environment. If a particular device requires only ports 80 and 443 to function, then it is quickly deduced that no other ports should be accessible from the outside world. If it is not possible to shut down the service on the particular device, then it should be blocked at either the router or the firewall, or in a best-case scenario it should be blocked at both the router and firewall.

Objective

The objective of this exercise is to show you how to quickly determine what services are running in your environment.

Requirements

Challenge Procedure

The following are the steps that you are going to perform for this exercise:

  1. Download and install SuperScan.

  2. Verify that you have an IP address bound to your NIC.

  3. Use ping to determine if a host is active. Use your host IP address as the target for the scans. Use your actual IP address, not the localhost IP address which is 127.0.0.1.

  4. Create shares for your system.

  5. Use SuperScan to find the open ports and running services on your system.

Challenge Procedure Step-by-Step

The following are the detailed steps you will perform to install and configure SuperScan:

  1. Download SuperScan from http://www.foundstone.com. Install SuperScan by clicking the install executable. When the SuperScan screen appears, click Next.

  2. Figure 6.16

  3. Click the Browse button to browse to the appropriate directory to install SuperScan. Install SuperScan into c:\Program Files\SuperScan.Then, click the Finish button.

  4. Figure 6.17

  5. After the installation is complete, start the application. You will see the following screen.

  6. Figure 6.18

  7. Verify that your TCP/IP stack is properly functioning. Ping the local loopback adapter by selecting Start, Run, cmd. Then, enter the following command:

  8. ping 127.0.0.1

    If you receive a reply, continue. If you do not receive a reply, verify your network settings. This is done by checking your IP address settings under the Network Properties window.

  9. Next, verify the port settings for your particular needs. This is done by looking under the Select Ports portion of the screen (in the lower-right) and making sure the correct ports are selected. The Change/Add/Delete Port Info section allows you to customize services that are running on particular ports. This is extremely helpful if you are running a specialized application on a specific port. It is also a way to make sure that your port listings are current.

  10. Figure 6.19

  11. After you have completed the port listing, you can enter the IP range that you would like to scan. SuperScan can also perform address resolution on IP addresses at this stage. Enter the IP address of the machine you want to resolve and click the Lookup button. The information on the corresponding host number will be displayed in the Resolved text field.

  12. Figure 6.20

  13. If the scanning device has multiple interfaces, you can select a specific interface for the scan to run on. Click the Interfaces button and select the appropriate interface. In most cases the default settings for the interfaces will work fine.

  14. Figure 6.21

  15. After the interface is chosen, the target IPs are entered, and the port list is defined, there are a few additional steps you can perform to customize your scan. These are as follows:

    • Under the Speed section is a slider that can be used to throttle the amount of bandwidth used by the scan as well as the resources used on the scanning device.

    • Under the IP section, the Ignore IP Zero and the Ignore IP 255 options can be used to either scan or ignore both the broadcast and network addresses in your range.

    • If you do not allow ICMP traffic in your environment, you can disable the initial ping. This is done with the Only Scan Responsive Ping check box.
  16. After the variables are defined, you can initiate the scan by clicking the Start button, which is located under the Scan section.

  17. Figure 6.22

    When the scan completes, the following screen appears listing the open ports on the target machine.

    NOTE

    Port listings can give an outsider a great deal of information about a device that an administrator might not want him to know. Ports, such as port 445, are inherent with Windows 2000, and port 139 is inherent with Windows 9x or Windows NT. If these ports are accessible to the Internet, then an intruder can quickly determine what potential vulnerabilities may exist on the target box. The attacker will then focus his attack on those vulnerabilities.

    Figure 6.23

    This information can be saved to a file for later review or for input into a vulnerability scanner.

Summary

One of the first things an attacker will do to gather information about your network is to run a port scan against it. SuperScan is a Windows-based scanner that can reveal a great deal of information about your environment. Therefore, it makes sound security sense to frequently run port scans against your environment to ensure that unneeded ports are not visible or accessible to unauthorized parties.

If you have an IDS system set up in your organization, you will see the externally facing network being scanned frequently. Many attackers have an automated scanning setup that will randomly scan IP addresses looking for vulnerable services or ports. The attackers can be very difficult to trace because a majority of these scans are launched from different locations through trojan computers. In many cases, the scanning system's administrator or owner has no idea that her machines are being used to scan other organizations' systems.

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