TI+IR/M: Quick Wins
The best way to understand how threat intelligence impacts your incident response/management process is to actually run through an incident scenario with commentary to illustrate the concepts. For simplicity’s sake we assume you are familiar with our recommended model for an incident response organization and the responsibilities of the tier 1, 2, and 3 response levels. You can get a refresher back in our Incident Response Fundamentals series. For brevity we will use an extremely simple high-level example of how the three response tiers typically evaluate, escalate, and manage incidents. If you are dealing with an advanced adversary things will be neither simple nor high-level. But this provides an overview of how things come together. The Trigger Intellectual property theft is a common mission for advanced attacker, so that will be our scenario. As we described in our Threat Intelligence in Security Monitoring paper, you can configure your monitoring system to look for suspicious IP ranges from your adversary analysis. But let’s not put the cart before the horse. Knowing you have valuable IP (intellectual property), you can infer that a well-funded adversary (perhaps a nation-state or a competitor) has a great interest in that information. So you configure your monitoring process to look for connections to networks where those adversaries commonly hang out. You get this information from a threat intelligence service and integrate it automatically into your monitoring environment, so you are consistently looking for network traffic that indicates a bad scene. Let’s say your network monitoring tool fires an alert for an outbound request on a high port to an IP range identified as suspicious via threat intelligence. The analyst needs to validate the origin of the packet so he looks and sees the source IP is in Engineering. The tier 1 analyst passes this information along to a tier 2 responder. Important intellectual property may be involved and he suspects malicious activity, so he also phones the on-call handler to confirm the potential seriousness of the incident and provides a heads-up. Tier 2 takes over and the tier 1 analyst returns to other duties. The outbound connection is the first indication that something may be funky. An outbound request very well might indicate an exfiltration attempt. Of course it might not but you need to assume the worst until proven otherwise. Tracing it back to a network that has access to sensitive data means it is definitely something to investigate more closely. The key skill at tier 1 is knowing when to get help. Confirming the alert and pinpointing the device provide the basis for the hand-off to tier 2. Triage Now the tier 2 analyst is running point on the investigation. Here is the sequence of steps this individual will take: The tier 2 analyst opens an investigation using the formal case process because intellectual property is involved and the agreed-upon response management process requires proper chain of custody when IP is involved. Next the analyst begins a full analysis of network communications from the system in question. The system is no longer actively leaking data, but she blocks all traffic to the suspicious external IP address on the perimeter firewall by submitting a high-priority firewall management request. After that change is made she verifies that traffic is in fact blocked. The analyst does run the risk of alerting the adversary, but stopping a potential IP leak is more important than possibly tipping off an adversary. She starts to capture traffic to/from the targeted device, just so a record of activity is maintained. The good news is all the devices within engineering already run endpoint forensics on their devices, so there will be a detailed record of device activity. The analyst then sets an alert for any other network traffic to the address range in question to identify other potentially compromised devices within the organization. At this point it is time to call or visit the user to see whether this was legitimate (though possibly misguided) activity. The user denies knowing anything about the attack or the networks in question. Through that discussion she also learns that specific user doesn’t have legitimate access to sensitive intellectual property, even though they work in engineering. Normally this would be good news but it might indicate privilege escalation or that the device is a staging area before exfiltration – both bad signs. The Endpoint Protection Platform (EPP) logs for that system don’t indicate any known malware on the device and this analyst doesn’t have access to endpoint forensics, so she cannot dig deeper into the device. She has tapped out her ability to investigate so she notifies her tier 3 manager of the incident. While processing the hand-off she figures she might as well check out the network traffic she started capturing at the first attack indication. The analyst notices outbound requests to a similar destination from one other system on the same subnet, so she informs incident response leadership that they may be investigating a serious compromise. By mining some logs in the SIEM she finds that the system in question logged into to a sensitive file server it doesn’t normally access, and transferred/copied entire directories. It will be a long night. As we have mentioned, tier 2 tends to focus on network forensics and fairly straightforward log analysis because they are usually the quickest ways to pinpoint attack proliferation and gauge severity. The first step is to contain the issue, which entails blocking traffic to the external IP to temporarily eliminate any data leakage. Remember you might not actually know the extent of the compromise but that shouldn’t stop you from taking decisive action to contain the damage as quickly as possible – per the guidance laid down when you built designed the incident management process. Tier 3 is notified at this point – not necessarily to take action, but so they are aware there might be a more serious issue. Proactive communication streamlines escalation. Next the tier 2 analyst needs to assess the extent of