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The difference between Highly Evasive Adaptive Threats (HEAT) and advanced persistent threats (APT)

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In the fast-paced world of enterprise security, the last two years have seen a whirlwind of change unlike any other. The rise of remote work, cloud migration, and Software-as-a-Service (SaaS) applications has revolutionized the way we do business, but it has also opened up a Pandora's box of security vulnerabilities. A new breed of attacker has emerged, one that has learned to weaponize the most crucial tool for knowledge workers today: the web browser. The Highly Evasive Adaptive Threats (HEAT) they’ve been leveraging to compromise browsers, gain initial access to the endpoint, and ultimately deploy threats like ransomware or malware are unmatched in their ability to evade detection.

Given their ability to evade detection and get malicious payloads onto endpoints, confusing HEAT attacks with advanced persistent threats (APTs) is an easy mistake to make. But there are key differences between the two, and they operate in completely different stages of the attack kill chain.

So how exactly do HEAT attacks differ from APTs? We recently sat down with our Senior Director of Cybersecurity Strategy, Mark Guntrip, to get to the bottom of it. During our interview, Mark took a deep dive into how HEAT attacks and APTs work, how threat actors are using them together in attacks, and weak points to look out for when it comes to defending against these attacks.

What is a Highly Evasive Adaptive Threat?

I think the details are in the name there, right? As you look at Highly Evasive Adaptive Threats (HEAT), there are a ton of threats out there by volume. But the key thing for the threat actors out there is to maximize their chances of success. The two key descriptors in the name are evasive and adaptive—very important as far as the attacker is concerned. They want them to be as evasive as possible to avoid detection.

So that means they understand how to bypass a particular technology or security technique that's commonly in place. Whether that's phishing detection on email or sandboxing, there's a reasonably well understood level of “standard” technology that's in place to protect organizations. And if they know that they can evade that type of detection, then they have a higher level of success.

Then you have the adaptive piece of it, how it changes over time in order to maintain that evasiveness. A good example is evading URL reputation, where rather than moving fast to register a domain populated with content and malware and push it out, attackers adapt to how URL reputation systems find out whether a site is malicious or not and behave in a way they know will be classified as legitimate. Attackers will register a domain for a certain amount of time before they use it so that it's not new. They then populate it with content that is all relevant and in a similar theme, so it gets categorized a certain way. And then once they confirm the site is seen as good, they can use it for an attack. If the URL reputation solutions or engine changes, then they can monitor that and change what they do with that website before they use it for a HEAT attack.

The other key thing is that it's really all about initial access. This isn't a new class of malware, necessarily. This is a method of getting malicious content onto a victim machine in a way that is highly effective. So whether that's ransomware, keyloggers, or any other type of malware, they use HEAT attacks to get it there.

Why should security teams care about HEAT attacks?

For starters, the volume of attacks. Threats in general are going up, but as we look at HEAT attacks and measure the frequency that they're being used, we’re seeing those increase as well. Some may not care about HEAT attacks, or they may but without labeling them as such. It’s still a problem for them.

I think the other big thing that they should care about is how HEAT attacks can be used by Ransomware as a Service (RaaS) operators to easily gain initial access. Some cybercriminals’ entire business model is to gain initial access into as many networks as they can and eventually sell it to someone who wants to deploy malware onto that network. They won't just sell it to one person, they'll sell it to multiple people, which multiplies the effects of the breach. A single breach can result in five, 10, 100 or even more threat actors being able to put their malware on that network. So you might not see it, you might not feel it because nothing happens, but you really need to care about it, you need to protect against it.

What’s an Advanced Persistent Threat (APT)?

An APT is a class of threats that are designed to be undetectable. Once they're in the network, they're designed to stay there for as long as possible and do whatever it is that the threat actor wants to do with that threat—whether it's searching around looking for data, stealing data, stealing credentials, or deploying ransomware. They're used by nation or state sponsored groups to go after high value targets, and recently, the term has been used more broadly to include some crimeware groups.

What's the difference between a HEAT attack and an APT?

The HEAT attack is used for the initial access piece to get into the network, and the APT can then be deployed. So they're very much two sides of the same coin, or two parts of the same process. You've got the HEAT attack that will be able to get you access to your target network, and then your APT will go and do whatever damage it is that you want it to do. The HEAT attack itself is not going to do any damage—it delivers the thing that does the damage. I think that's the big difference between the two. But they shouldn't necessarily be thought of as distinct and separate, because they can be put together and even used in the same attack. For example, the Nobelium attack used HTML smuggling, which is a HEAT characteristic, to deliver APTs down to their victims. That's a good example of the two being used hand in hand as opposed to being overlapping or separate

As we head into the thick of the year, what do you think cybersecurity teams should know about HEAT attacks and modern work?

One of the key things here is looking at hybrid work and people working remotely on any device connected to the corporate network, whether it's a cell phone or something else, they all have to be treated like a single system. If you use a Mac, that's connected to your iCloud, and so anything coming through and attacking you personally as a consumer, or maybe as a professional because they know who you work for, can be relayed to your corporate device.

The impact of that potential exposure, especially as it relates to HEAT attacks, can be huge. Coming back to the fact that the HEAT is all about the initial access, if somebody can get initial access into a personal device of mine—I'll call it an unmanaged device—that can be used to access corporate resources. That's a huge issue that's almost exactly the same or just as bad, at least, as having initial access into a corporate owned device with all of those same rights.

The other key thing to be aware of is the adaptive side of things. Obviously, things are going to change. Attackers are getting better at tricking the technology that's in place to secure organizations, but also tricking the humans that are being used to click on the link, download the file, whatever it might be, to activate the threat. And so as we go through the years, I think not only do we need more education about what to look for with HEAT attacks and how they work, but also to have improved visibility control around what a HEAT attack might look like as it's trying to come in. So we talk about prevention a lot, but I think we also need to have better levels of detection as well.

The third thing, and this may be the most important one, is visibility into the browser. HEAT attacks exist among web traffic. They exist in the browser, and though the browser is on an endpoint, endpoint security solutions don't necessarily have visibility into what's going on inside a browser. Inside a browser is a massively powerful platform where you can run scripts and execute code. You can do all this stuff inside the application before anything happens. This is a huge potential blind spot. Not only is the browser a blind spot, but it’s also the most targeted access point.

We spend so much time online on a browser. Every single device has a browser—there are probably more browsers than devices. It’s the most widely deployed enterprise application. We use browsers to access everything, not just websites, but applications. The browser encompasses everything else that we use to live our lives and do work, yet for traditional security solutions like endpoint detection and response (EDR), it’s a visibility black hole. It doesn’t have to be.

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