Building a Threat Intelligence Program: Using TI
As we dive back into the Threat Intelligence Program, we have summarized why a TI program is important and how to (gather intelligence. Now we need a programmatic approach for using TI to improve your security posture and accelerate your response & investigation functions. To reiterate (because it has been a few weeks since the last post), TI allows you to benefit from the misfortune of others, meaning it’s likely that other organizations will get hit with attacks before you, so you should learn from their experience. Like the old quote, “Wise men learn from their mistakes, but wiser men learn from the mistakes of others.” But knowing what’s happened to others isn’t enough. You must be able to use TI in your security program to gain any benefit. First things first. We have plenty of security data available today. So the first step in your program is to gather the appropriate security data to address your use case. That means taking a strategic view of your data collection process, both internally (collecting your data) and externally (aggregating threat intelligence). As described in our last post, you need to define your requirements (use cases, adversaries, alerting or blocking, integrating with monitors/controls, automation, etc.), select the best sources, and then budget for access to the data. This post will focus on using threat intelligence. First we will discuss how to aggregate TI, then on using it to solve key use cases, and finally on tuning your ongoing TI gathering process to get maximum value from the TI you collect. Aggregating TI When aggregating threat intelligence the first decision is where to put the data. You need it somewhere it can be integrated with your key controls and monitors, and provide some level of security and reliability. Even better if you can gather metrics regarding which data sources are the most useful, so you can optimize your spending. Start by asking some key questions: To platform or not to platform? Do you need a standalone platform or can you leverage an existing tool like a SIEM? Of course it depends on your use cases, and the amount of manipulation & analysis you need to perform on your TI to make it useful. Should you use your provider’s portal? Each TI provider offers a portal you can use to get alerts, manipulate data, etc. Will it be good enough to solve your problems? Do you have an issue with some of your data residing in a TI vendor’s cloud? Or do you need the data to be pumped into your own systems, and how will that happen? How will you integrate the data into your systems? If you do need to leverage your own systems, how will the TI get there? Are you depending on a standard format like STIX/TAXXI? Do you expect out-of-the-box integrations? Obviously these questions are pretty high-level, and you’ll probably need a couple dozen follow-ups to fully understand the situation. Selecting the Platform In a nutshell, if you have a dedicated team to evaluate and leverage TI, have multiple monitoring and/or enforcement points, or want more flexibility in how broadly you use TI, you should probably consider a separate intelligence platform or ‘clearinghouse’ to manage TI feeds. Assuming that’s the case, here are a few key selection criteria to consider when selecting a stand-alone threat intelligence platforms: Open: The TI platform’s task is to aggregate information, so it must be easy to get information into it. Intelligence feeds are typically just data (often XML), and increasingly distributed in industry-standard formats such as STIX, which make integration relatively straightforward. But make sure any platform you select will support the data feeds you need. Be sure you can use the data that’s important to you, and not be restricted by your platform. Scalable: You will use a lot of data in your threat intelligence process, so scalability is essential. But computational scalability is likely more important than storage scalability – you will be intensively searching and mining aggregated data, so you need robust indexing. Unfortunately scalability is hard to test in a lab, so ensure your proof of concept testbed is a close match for your production environment, and that you can extrapolate how the platform will scale in your production environment. Search: Threat intelligence, like the rest of security, doesn’t lend itself to absolute answers. So make TI the beginning of your process of figuring out what happened in your environment, and leverage the data for your key use cases as we described earlier. One clear requirement for all use cases is search. Be sure your platform makes searching all your TI data sources easy. Scoring: Using Threat Intelligence is all about betting on which attackers, attacks, and assets are most important to worry about, so a flexible scoring mechanism offers considerable value. Scoring factors should include assets, intelligence sources, and attacks, so you can calculate a useful urgency score. It might be as simple as red/yellow/green, depending on the sophistication of your security program. Key Use Cases Our previous research has focused on how to address these key use cases, including preventative controls (FW/IPS), security monitoring, and incident response. But a programmatic view requires expanding the general concepts around use cases into a repeatable structure, to ensure ongoing efficiency and effectiveness. The general process to integrate TI into your use cases is consistent, with some variations we will discuss below under specific use cases. Integrate: The first step is to integrate the TI into the tools for each use case, which could be security devices or monitors. That may involve leveraging the management consoles of the tools to pull in the data and apply the controls. For simple TI sources such as IP reputation, this direct approach works well. For more complicated data sources you’ll want to perform some aggregation and analysis on the TI before updating rules running on the tools. In that case you’ll expect your TI platform for integrate with the tools. Test and Trust: The key concept here is trustable automation. You want to make sure any rule changes driven by TI go
