Fileless protection explained: Blocking the invisible threat others miss

Most antivirus software for personal users scans your computer for malware hiding in files. This is, after all, how most malware is traditionally spread. But what about attacks that never create files? Fileless malware is a fast-growing threat that evades traditional antivirus software, because simply, it’s looking for files that don’t exist.

Here’s how Malwarebytes goes beyond signature scans and file analysis to catch those fileless threats hiding on your family’s computers.

****What are fileless attacks?** **

Most malware leaves a trail. It drops files on your hard drive so it can survive when you restart your computer. Those files are what traditional antivirus software hunts for.

Fileless attacks play by different rules, living only in your computer’s active memory. This means they vanish when you reboot, but they do their damage before that happens.

Fileless attacks don’t bring in their own files at all. Instead, they hijack legitimate Windows tools that your computer already trusts. PowerShell, for example, is a built-in program that helps Windows run everyday tasks. Fileless malware slips into memory, runs harmful commands through tools like PowerShell, and blends in with normal system activity.

Because Windows sees these tools as safe, it doesn’t throw up red flags. And because there are no malicious files saved to the disk, traditional antivirus has nothing to scan or quarantine, missing them completely.

Fileless attacks are becoming more common because they work. Cybercriminals use them to steal your passwords, freeze your files for ransom, or turn your computer into a cryptocurrency-mining machine without you knowing.

****How Malwarebytes stops these invisible attacks** **

Malwarebytes takes a different approach. Instead of just scanning files on your hard drive, we watch what programs are actually doing in your computer’s memory. We developed comprehensive protection creating a defense system that works in two powerful ways:

Defense Layer 1: Script Monitoring

Script Monitoring catches dangerous code before it runs. Whether it’s PowerShell, VBScript, JavaScript, or other scripts, we inspect them the moment they try to execute. Malicious? Blocked instantly. Safe? Runs normally.

Attackers scramble their malicious code so it looks like gibberish. Imagine a secret message where every letter is shifted three places in the alphabet. Our technology automatically decodes these scrambled commands, revealing what they’re really up to.

Defense Layer 2: Command-Line Protection

Command-Line Protection tracks what programs are trying to do when they run commands on your system.

When programs like PowerShell, Windows Script Host, or other command tools run, we examine what they’re trying to do. Are they downloading files from suspicious websites? Trying to modify system files? Attempting to turn off security software? We catch these patterns even if attackers try to bypass the first layer of defense.

**What might a fileless attack look like? **

Let’s look at specific attack scenarios and how Malwarebytes protects you:

****Attack scenario 1: The disguised email attachment** **

You receive what looks like a legitimate invoice or document via email. When you open the Excel or Word attachment, it contains a macro (a small script that automates tasks). The macro looks harmless at first glance, but it’s actually scrambled to hide malicious commands.

What happens next: The macro silently launches PowerShell in the background and tries to download ransomware. Your traditional antivirus sits idle because it’s waiting to see a file – but the file hasn’t been created yet.

How Malwarebytes stops it: Our Script Monitoring unscrambles the macro, sees it trying to download ransomware, and blocks the PowerShell command immediately. The ransomware never reaches your computer. You see a notification that Malwarebytes blocked a threat, and your files stay safe.

****Attack scenario 2: The silent cryptocurrency miner** **

You visit a normal-looking website or click on an ad. Hidden JavaScript code starts running immediately, hijacking your computer’s processor to mine cryptocurrency. You notice your laptop fan spinning louder, the computer running hotter, but you don’t connect the dots. Meanwhile, your electricity bill creeps up month after a month.

What happens next: The script tries to load mining software directly into your computer’s memory using PowerShell or similar tools. It runs continuously in the background, stealing your computing power.

How Malwarebytes stops it: Our Command-Line Scanner recognizes the mining script’s pattern and blocks it before it can start using your processor. Your computer maintains normal performance, and criminals can’t abuse your resources.

****Attack scenario 3: The persistent backdoor** **

A sophisticated attacker wants long-term access to your computer. They use Windows Management Instrumentation (WMI), a legitimate Windows tool, to create a persistent backdoor. This backdoor lets them access your computer whenever they want, all without installing any traditional malware files.

What happens next: Using WMI, they set up scheduled tasks that run invisible scripts in the background. These scripts give them a permanent remote access pass to your computer. Restart doesn’t help. The backdoor survives because it’s woven into Windows itself, disguised as a normal system task.

How Malwarebytes stops it: Our protection monitors WMI activity for suspicious patterns. When we detect WMI being used to create unauthorized backdoors or scheduled tasks, we block the commands and alert you. The backdoor never gets established.

About Fileless Protection in Malwarebyes

When choosing security software, ask: Can it protect against attacks that never write files? Can it catch memory-based threats? With Malwarebytes, the answer is yes.

Runs automatically

You don’t need to set anything up. Fileless Protection runs quietly in the background from the moment you install it. You won’t notice it until it blocks an attack and keeps your files safe.

Works with your everyday tools

Your legitimate programs and scripts work normally. You can run PowerShell, use your business software, and browse the web without interruption. We only step in when there’s a real threat.

Part of a bigger defence

Fileless Protection is one layer in Malwarebytes’ broader security stack, working alongside machine-learning detection, web protection, and exploit protection. Each layer supports the others, so if one misses something, another catches it.

Stops attacks that never write files

Fileless attacks hide in memory, but they’re not unstoppable. Fileless Protection watches what programs do in memory, analyzes suspicious commands, and blocks attacks before they can steal data or damage your files.

Included with Malwarebytes Premium

Fileless Protection is included in Malwarebytes Premium. Whether you’re protecting your home devices or your small business systems, Malwarebytes works automatically, stays out of your way, and catches threats that traditional antivirus often misses.

We don’t just report on threats—we remove them

Cybersecurity risks should never spread beyond a headline. Keep threats off your devices by downloading Malwarebytes today.

About the author

Core Technology is the team behind the protection engine that powers Malwarebytes products. From threat detection and performance optimization to SDK innovation and telemetry, the group builds the foundational technology that keeps users safe across every platform.