Beyond the Horizon: Why Proactive Threat Hunting is a Game-Changer for Your Security

Welcome to our discussion on a crucial aspect of modern cybersecurity: threat hunting. Today, we’re moving beyond the traditional reactive approaches and delving into why a proactive threat hunting strategy is not just beneficial, but essential for uncovering more threats and staying ahead of adversaries.

You might be familiar with the term threat hunting, but the distinction between “reactive” and “proactive” can make all the difference. Let’s break down these concepts and illustrate how adopting a proactive mindset can transform your security posture.

Understanding the Knowns and Unknowns in Your Threat Landscape

When we talk about threat hunting, it’s helpful to categorize threats based on what we know about them and their capabilities. This is often visualized in four quadrants:

1. Known Knowns: These are the most straightforward: known threats using known capabilities. Think of well-documented attack methods from established threat actors like APT29 or APT34. Threat intelligence feeds are rich with this information, providing indicators of compromise (IOCs) and tactics, techniques, and procedures (TTPs) to search for. Hunting for known knowns is entirely reactive. You’re essentially waiting for intelligence to tell you what to look for based on past incidents. While valuable, if this is your sole focus, you’re only scratching the surface.

2. Unknown Knowns: This quadrant covers unknown threats using known capabilities. Imagine you’re hunting for evidence of a tool commonly used by a known APT group, like PSExec or Mimikatz. In the process, you might stumble upon a different, previously unidentified attacker leveraging that same tool. Here, your threat intelligence pointed you to a known capability, but you’ve proactively uncovered a new threat actor. This approach is a mix – partly reactive (due to the known capability) and partly proactive (due to finding an unknown threat).

3. Known Unknowns: Here’s where we enter truly proactive territory. This involves looking for unknown capabilities used by known threats. Even the most sophisticated threat intelligence won’t reveal every tool or technique an adversary, especially a nation-state actor, has in their arsenal. They invest heavily in developing new methods that haven’t been seen in the wild. By hunting for novel or unexpected behaviors from known adversaries, you’re anticipating their evolution rather than just reacting to their documented history.

4. Unknown Unknowns: This is the most challenging category: unknown capabilities used by unknown threats. Discovering these often comes down to deep analytical work, anomaly detection, or sometimes, sheer luck during a hunt focused elsewhere. These are the threats you don’t know you don’t know about.

If your threat hunting program exclusively targets “known knowns,” it’s 100% reactive. You’re waiting for an intel report before you act. When you start exploring “unknown knowns,” you’re about 50% reactive and 50% proactive. However, to be truly proactive, you need to venture into the left side of this landscape, hunting for “unknown capabilities,” regardless of whether the threat is known or not. This means assuming attackers are constantly innovating.

The Black Swan Theory: Preparing for the Unexpected in Cybersecurity

The concept of “Black Swan” events, popularized by Nassim Nicholas Taleb, is incredibly relevant to cybersecurity. Historically, it was believed that all swans were white until black swans were discovered in Australia. This metaphor describes events that meet three criteria:

1. They are outliers: They fall outside the realm of regular expectations because nothing in the past can convincingly point to their possibility.
2. They carry an extreme impact. ¹    
3. They are explainable in hindsight: After the event occurs, human nature makes us concoct explanations for its occurrence, making it appear predictable.

Think about major cybersecurity incidents: the SolarWinds supply chain attack, the exploitation of MS17-010 in WannaCry ransomware, or sophisticated attacks on industrial control systems. These were often outliers, had a massive impact, and, in retrospect, the vulnerabilities and attack paths became clear.

A purely reactive threat hunting approach, focusing only on known knowns, leaves you highly vulnerable to Black Swan events. Threat intelligence, by its nature, primarily reports on what has already happened and been observed.

Consider Taleb’s analogy of the turkey: fed every day by the farmer, the turkey believes life is good and the farmer is its friend. Its confidence grows with each feeding. The Black Swan event for the turkey is the week before Thanksgiving. This illustrates how a system built on past observations can catastrophically fail when an unpredicted event occurs. In infosec, we must avoid being the turkey.

Possible vs. Probable: Expanding Your Threat Hunting Focus

Many organizations focus their resources on threats they deem “probable.” This often aligns with the “known knowns” – threats that are well-documented and have a high likelihood of appearing.

• Possible and Probable: These are legitimate threats that should absolutely be on your radar.
• Not Possible but Probable (or Not Possible and Not Probable): If an event isn’t technically possible in your environment, investing resources to hunt for it is wasteful. This is often where fear, uncertainty, and doubt (FUD) can lead to misallocated budgets.

The critical area many miss is Possible but Not Probable. These are events or capabilities that could impact your environment, but you might not deem them likely, perhaps because no specific threat intelligence has linked them to an actor targeting your sector. If you’re only hunting for what’s probable (based on existing intel), you’re missing a significant portion of the threat landscape. A proactive approach acknowledges that if an attack vector is possible, it’s worth investigating, even if it’s not currently flagged as “probable.”

Practical Steps to Embrace Proactive Threat Hunting

So, how can you shift your threat hunting from a reactive stance to a more proactive one, and start uncovering those potential Black Swans?

1. Start with “Known Unknowns”:

   • Focus: Hunt for known adversaries potentially using capabilities they haven’t been observed using before.
   • Actionable Start: Begin with capabilities that have low adoption friction for attackers. These are often popular, readily available tools or simple techniques. Many tactics in the MITRE ATT&CK framework can be executed with a single command line, making them easy for attackers to implement.
   • Examples:
     
     • Living Off the Land Binaries (LOLBins): Legitimate system tools that can be abused by attackers. (Search for “LOLBAS project” for a great resource).
     • PSExec: A legitimate sysadmin tool often co-opted by attackers for lateral movement.
     • PyInstaller: Used to package Python scripts into executables, it has been seen in nation-state campaigns to deploy malware. If APTs are using it, it’s a capability worth hunting for generally.
     • Mimikatz: A notorious tool for credential theft. While your red team might use it, many APT groups do too.
   • Progression: Once you’ve covered the low-hanging fruit, move to more complex or less common capabilities.

2. Expand to “Unknown Knowns”:

   • Focus: Search for known capabilities and TTPs without initially tying them to a specific threat actor. The goal is to detect the behavior, regardless of who is behind it.
   • Shift in Mindset: Pivot from a threat-focused hunt (e.g., “Let’s look for APT34”) to a capability-focused hunt (e.g., “Let’s look for unusual PSExec activity” or “Let’s hunt for evidence of PyInstaller usage”).
   • Avoid Blinders: Be open to the possibility that the activity you uncover might not be from the adversary you initially suspected, or any known adversary at all. The aim is to find malicious activity, period.

Moving Forward: The Proactive Imperative

The cybersecurity landscape is dynamic, with attackers constantly evolving their tools and techniques. Relying solely on reacting to known threats is like driving while only looking in the rearview mirror.

By incorporating hunts for “known unknowns” (new tricks from old dogs) and “unknown knowns” (familiar tools in new, unknown hands), you significantly broaden your detection capabilities. This proactive stance doesn’t just prepare you for the threats of today, but also helps you build resilience against the unexpected “Black Swan” events of tomorrow.

Start thinking beyond the latest threat intelligence report. Consider what’s possible in your environment, not just what’s been reported as probable. By doing so, you’ll be far better equipped to defend your organization against a wider spectrum of cyber threats.