Cyber Security

Fileless malware is a sophisticated type of attack that evades traditional antivirus software by using legitimate tools to execute malicious activities. It operates without leaving traces on a hard drive, making detection challenging.

So, how can you protect your system against attacks like this?

Read on to learn how attackers automate this attack and exploit your OS environments through living-off-the-land tactics!

What is Fileless Malware?

Fileless malware is a stealthy variant of malware that doesn’t rely on files stored on a computer’s hard drive to infect systems. Instead, it exploits the operating system and legitimate tools like PowerShell or the Windows Registry to carry out malicious actions.

Common Fileless Malware Techniques

Fileless malware leverages advanced fileless techniques to bypass traditional detection systems. Below are some of the most common attack scenarios for executing this type of malware.

Exploit Kits

Exploit kits refer to collections of exploits (collections of data, sequences of commands, or pieces of code).

These kits enable attackers to infect a targeted system with malicious software directly into memory through vulnerabilities in software or OS, typically delivered via phishing emails or social engineering tactics.

Hijacked Native Tools

Attackers exploit tools like Microsoft Windows PowerShell and Windows Management Instrumentation (WMI) to execute fileless malware work.

These tools were supposedly intended for task automation and configuration management. However, these attackers abuse them to perform malicious activities.

Registry Resident Malware

Registry resident malware embeds malicious code straight into the Windows Registry, allowing it to persist without being written to disk. It often runs as part of legitimate Windows processes.

Memory-only Malware

Memory-only malware operates entirely in the system’s memory. One notorious example of memory-only malware is the Duqu worm 2.0, which was designed to steal information from industrial control systems using advanced features like lateral movement, reconnaissance, and data exfiltration.

Fileless Ransomware

With fileless ransomware, attackers combine the stealth of fileless techniques with the destructive power of ransomware.

Attackers use this method to hijack native tools, encrypt files, and demand ransom, often leveraging command and control infrastructure to coordinate attacks.

Stolen Credentials

Attackers often use PowerShell scripts and Windows Management Instrumentation (WMI) to steal credentials and infiltrate systems. By abusing these tools, they bypass defenses and compromise the network.

They can stay hidden by embedding their code in the system registry or kernel or by creating user accounts that give them access to any system they target.

How Does a Fileless Attack Happen?

Explore this step-by-step breakdown of how a fileless attack unfolds in action:

1. The attacker tricks someone into clicking a harmful link or opening a fake attachment, usually in a phishing email.
2. Once the user clicks or opens the malicious link or attachment, the attackers will gain access to the system.
3. Instead of adding new programs, they hijack tools already on the system to run harmful commands. For instance, Shellcode launches Powershell with a cmd line to download and then execute the payload in the system’s memory.
4. The malware operates directly in the system’s memory, leaving no files behind to trigger alarms.
5. The attacker uses weak spots or stolen credentials to move from one system to another.
6. Finally, they steal data, disrupt operations, or achieve their goal without leaving obvious signs.

How To Detect Fileless Malware Attacks

In general, you can detect fileless malware in two ways: using indicators of attack and managed threat-hunting. Take a look at the details. 

Use Indicators of Attack Instead of Indicators of Compromise

Focusing on Indicators of Attack (IoAs) helps identify ongoing malicious activity. Since fileless malware gets embedded in legitimate processes, tracking unusual PowerShell processes or irregularities in applications running is critical.

This method allows for detecting malicious behavior as it happens rather than relying on past breaches for clues.

Use Managed Threat-hunting

Managed threat-hunting services play a key role in identifying and stopping fileless malware. These services monitor Windows scripts and system behavior across multiple devices to spot potential threats.

By analyzing suspicious actions and deploying detection and prevention methods, they can quickly respond before malware has the chance to infect a computer.

How Can You Defend Against Fileless Attacks?

Proper defense against fileless attacks requires multiple layers of effort. Here are key defenses to do:

• Monitor system behavior
• Keep software updated
• Use endpoint detection and response (EDR)
• Implement application whitelisting
• Train your team
• Leverage managed threat hunting services
• Adopt a multi-layered security approach

Combining these strong defenses can significantly reduce the risk of fileless malware compromising your systems.

Frequently Asked Questions

Conclusion

Fileless malware is a sophisticated threat that avoids detection by traditional tools, making it critical to stay ahead with advanced security measures. Detecting fileless malware requires monitoring system behavior, implementing proactive prevention methods, and updating the system.

Given the complexity of these attacks, partnering with a professional cybersecurity agency is great for protection. A trusted agency like Fluxgate can help identify vulnerabilities, respond to threats, and safeguard your systems.

Contact us today for expert assistance in defending against fileless attacks!