Every Question Tells a Story – Mitigating Ransomware Using the Rapid Cyberattack Assessment Tool: Part 1


They say that a picture is worth 1,000 words.

But in some cases, the questions that you ask can also help tell a very interesting story.

Let me explain.

All of us are familiar with the devastating effects of ransomware that we saw last year in the WannaCry, Petya, NotPetya, Locky and SamSam ransomware attacks. We read the stories of the massive financial impact these attacks had on their victims, and we can only imagine the stress that the individuals in the IT departments of the impacted organizations went through trying to recover.

You may know that Microsoft has created a tool called the Rapid Cyberattack Assessment. The intent of the tool is to help an organization understand the potential vulnerabilities and exposures they have to ransomware attacks so that they can take steps to keep from being the next victim.

But like I said - every question tells a story - and in this tool there are many questions that an IT admin needs to ask himself or herself, and there’s a story behind each of these questions that helps make the tool’s value evident.

Let's take a look at the tool and as we go through the tool I'll try to give you the story behind each question.

Preparing the Environment

First, let’s download the tool itself.

It’s a free download from Microsoft, located here:

https://www.microsoft.com/en-us/download/details.aspx?id=56034

It’s important to download both the executable (RCA.exe) and the requirements document. The requirements document is also important, because if you don’t set up the tool correctly as well as the target machines, you likely won’t get some information that’s very valuable.

Conditions

First of all, you need to be aware that the Rapid Cyberattack Assessment tool runs in an Active Directory environment, and against Windows machines only. Any machines that you target with the tool must be part of an Active Directory domain. Additionally, the tool is limited in scope to 500 machines.

What should you do if your environment is larger than that?

There are really two simple options:

  1. Assess your entire environment in 500 machine chunks. Run the tool against a specific OU or group of OU’s that total no more than 500 machines. You can also just create lists (maybe exported from a spreadsheet) and use that as input for the tool. This method will definitely take a little bit of time and it won’t give you a single, comprehensive report view, either.
  2. Take sample machines from a number of different departments and run the tool against them. With this method, you would take (as an example) 50 machines from HR, 50 machines from Finance, 50 machines from Sales, etc…and run the tool against them. It doesn’t capture data on every single machine in the environment, but the tool is designed to give you an idea of where your exposures lie, and that would most likely be revealed in even a random sampling of machines. You can reasonably assume that any vulnerabilities identified in that subset of machines likely exists elsewhere in the environment as well.

Personally, if I was running the tool in my own environment and we had more than 500 machines, I would choose the second option. It gives me a rough idea of the issues I have to resolve and helps me prioritize them. If my environment has more than 500 machines, I’m probably managing them with some sort of automation tool anyway (like System Center Configuration Manager), so I don’t have to know exactly how each machine is configured. I’ll just define what the standard should be and push out that configuration.

Hardware and Software

Installing the Rapid Cyberattack Assessment tool itself isn’t hard at all. You simply run the RCA.exe executable. There aren’t any options or choices to make other than agreeing to the license terms. Likewise, the machine you run the tool from doesn’t have a lot of requirements. It should be:

  1. Server-class or high-end workstation running Windows 7/8/10 or Windows Server 2008 R2/2012/2012 R2/2016.
  2. It’s preferable to have a machine with 16 GB+ of RAM, a 2 GHz+ processor and at least 5 GB disk space.
  3. The machine should be joined to the Active Directory domain you will be assessing.
  4. Microsoft .NET Framework 4.0 must be installed
  5. Optionally, you may want Word, PowerPoint and Excel installed to view the reports. But you can also just export the reports and view them on a machine that has Office installed already.

Account Rights

The service account you use to run the tool needs to be a domain user who has local administrator permissions to all the machines within the scope of the assessment. The account should also have read access to the Active Directory forest that the in-scope computers are joined to.

Network Access

The machines you are trying to assess obviously must be reachable by the assessing machine. Therefore, there must be unrestricted access from the tools machine to any of the in-scope domain joined machines. By “unrestricted access” we mean you should make sure there are no firewall rules or router ACLs that would block access to any of the following protocols and services:

  • Remote Registry
  • Windows Management Instrumentation (WMI)
  • Default admin shares (C$, D$, IPC$)

If you are using Windows Advanced Firewall on the in-scope machines, you may need to adjust the firewall to allow the assessment tool to run.

You can configure this using a Group Policy targeted at the in-scope machines. To do this, follow these steps.

  1. Use an existing Group Policy object or create a new one using the Group Policy Management Tool.
  2. Expand the Computer Configuration/Policies/Windows Settings/Security Settings/Windows Firewall with Advanced Security/Windows Firewall with Advanced Security/Inbound Rules
  3. Check the Predefined:radio button and select Windows Management Instrumentation from the drop-down list. Click 
  4. Check the WMI rules for the Domain Profile. Click Next
  5. Check the Allow the Connectionradio button and click Finish to exit and save the new rule.
  6. Make sure the Group Policy Object is applied to the relevant computers using the Group Policy Management Tool

You would then do the same thing for: Allow file and Print sharing exceptions

For the Remote Registry Service, you want to set the service to Automatic startup for the duration of the assessment.

  1. Open the Group Policy editor and the GPO you want to edit.
  2. Expand Computer Configuration > Policies > Windows Settings > Security Settings > System Services
  3. Find the Remote Registry item and change the Service startup mode to Automatic
  4. Reboot the clients to apply the policy

That should be enough to get you started.

In the next post, I’ll walk you through the survey questions in the Rapid Cyberattack Assessment tool.

https://blogs.technet.microsoft.com/cloudyhappypeople/2018/09/10/every-question-tells-a-story-mitigating-ransomware-using-the-rapid-cyberattack-assessment-tool-part-2/

I think you’ll find the stories revealed by the questions to be quite interesting.

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