NetSPI Blog

The Systems That Time Forgot

Scott Sutherland
June 15th, 2010

Do you know about ALL of the systems on your network? If so, you’re in the minority. Identifying and actively managing all the systems on a network is not an easy task. Environments are constantly changing, asset owners come and go, and without a good asset management process, systems get lost in the shuffle. Unfortunately, many organizations don’t take asset management into account when developing their vulnerability management programs. As a result, systems are left unmanaged, misconfigured, and unpatched. As you might guess, malware, attackers and penetration testers are often able use these systems as entry points and leverage their trust relationships to gain administrative control over the network. It’s hard to protect systems you don’t know are there, but there are some controls that can be put into place to reduce the risk they present to your environment.

What systems are typically affected?

Almost any system can drop off the radar, but usually they’re not high profile systems that require a lot of attention like domain controllers or critical application servers. In my experience, the systems most likely to fall through the cracks include test servers, and legacy application servers.

How can I get started doing asset management?

Good asset management starts with knowing what systems are on your network to begin with. So choosing an asset management solution and performing periodic device discovery on known network segments are good first steps. Once systems are identified they can be entered into the inventory and assigned an owner, asset value, and other data that can be used to prioritize IT tasks like vulnerability remediation. Below are some basic steps that can help network administrators get started:

  1. Choose an asset management solution for your environment. There are quite a few commercial and open source options available. Many of them are capable of performing dynamic device identification, but some of them are only able to find certain types of systems. Regardless, I recommend doing some independent research to find the one that works best for your environment and budget. Like most things, you get what you pay for, but below are few tools that I see being used on a fairly regular basis:    – Freeware tool: OpenNMS    – Freeware tool: Network Asset Manager    – Commercial tool: Orion IP Address Manager    – Commercial tool: Altiris Asset Management Suite
  2. Perform periodic asset discovery on known network segments. The goal of asset discovery is to basically identify any device on the network with an IP address. That includes everything from Windows mail servers to loading dock hand scanners. If it’s on the network, you want to know about it. As I mentioned before many of the commercial asset management tools have this functionality built in. However, I understand that not everyone has pockets lined with gold. So for the biggest bang for your buck I recommend Nmap. It’s incredibly flexible and comes at a great price (free). However, remember that ping scans by themselves aren’t enough. Many systems and networks are configured to drop ICMP requests, so it’s a good idea to perform some TCP and UDP scans as well.
  3. Assign asset ownership & transfer asset ownership as necessary. An asset owner’s role is very similar to that of a parent. They are responsible for the care and protection of their systems. As a result they perform such nurturing tasks as applying missing patches, implementing secure configurations, and maintaining up to date virus definitions. If there is no asset owner assigned to perform such duties for a system, it will eventually fold to an emerging vulnerability.
  4. Assign an asset value to each system based on the potential business impact. Typically this value is loosely based on the amount of revenue generated from the system; the type of information stored on the system, and the logical placement of the system on the network. However, keep in mind that the asset value doesn’t necessarily have to be a monetary. It could be a number 1 through 5. The point is having a method to help prioritize IT efforts.

How can I reduce the risk associated with unmanaged systems on my network?

This is a common question, and below are some common answers. Keep in mind that not all of them are appropriate for every environment.

  1. Develop secure configuration baselines for each device type and operating system. This will help to ensure that if a system drops off of the radar that at least it’s less likely to be susceptible to common attacks. Enforcing password complexity and account lockouts to help prevent brute force attacks is a basic example.
  2. Conduct periodic audits on a sample of the configurations to verify compliance. This will help to identify procedural gaps that may contribute to the implementation of insecure system configurations.
  3. Perform periodic vulnerability scanning of systems. This will help to identify common vulnerabilities on known systems. Once vulnerabilities are remediated, the systems will be less susceptible to common attacks.
  4. Perform periodic patch scans and updates (OS and 3rd party applications). Once vulnerabilities are remediated, the systems will be less susceptible to common attacks.
  5. Implement Network Access Control Systems (NAC). Implement a NAC that is capable of dynamic device detection and can quarantine systems that do not meet the minimum security requirements.
  6. Implement Port Security. Ensure vendors and employees can’t easily connect to the network by disabling unused network ports.

Final Thought

It is very common for penetration testers to leverage unmanaged systems as entry points that lead to complete network takeovers. The reality is that there are some unmanaged systems on every large network. So the bad news is that PCI, HIPAA, Personal Identifiable Information (PII), and the rest of your sensitive data is constantly being put at risk by these anonymous threats. The good news is that you have options. Hopefully the information in this blog gave you a place to start. Resource Links

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