Fileless Malware – Everything That You Need To Know About It

Malware comes in various different forms and intensities and here we are going to discuss one of the most dangerous malware out there, the Fileless Malware.

The name itself raises a lot of curiosity, as to how can this malware be spread when there is no file involved. More specifically, you might be thinking how can a Fileless Malware conquer my PC when for example, you haven’t even downloaded a file.

Also Read: Malware: A War We Never Asked For

How about getting a little into the brains of an attacker? An attacker would possibly use Fileless Malware –

  • Since, under normal circumstances, it would go undetected by an Antivirus. Why? We’ll discuss this a little later in the post.
  • There is no file or digital signatureto detect.
  • An attacker would mostly use legit tools that are right there in Windows. In a way, the attacker would turn Windows against itself.

Now let’s dive deeper, shall we?

What is Fileless Malware?

Fileless Malware, as the name suggests, is a malicious program that doesn’t rely on files to spread the malware. This means it doesn’t need to infect a file with the virus to cause destruction. Then how does it exploits a computer? It exploits the commonly used applications and built-in tools to carry out attacks. It uses legitimate programs to infect a PC. In a way, it turns your Windows PC against itself. Something that makes a Fileless Malware differ from a traditional attack is that the attacker doesn’t install a code on the infected PC and as such a Fileless Malware is hard to detect.

How Does A Fileless Malware Operate?

A Fileless Malware falls into LOC or low-observable characteristics attacks. These attacks are stealth attacks that evade detection by most security solutions. A Fileless Malware operates in your computer’s Random Access Memory and never touches your computer’s hard drive. An attacker instead uses vulnerable software that’s already present on a computer to take control and execute the attack.

Once the attacker has an access to your computer, the attacker can exploit Windows Management Instrumentation (WMI) or Windows PowerShell to carry out malicious activities.

At some point, you might be wondering, how on Earth can this get past my security solution? Since many security technologies trust these utilities, the malicious activities can remain undetected. Furthermore, since a Fileless Malware leaves nothing written directly onto your hard drive, there are no files stored that the security software can scan. To add on, a Fileless Malware doesn’t leave any footprints or signatures that your Antivirus would normally identify.

What Are The Different Stages of Fileless Malware?

Stage I:


The attacker exploits a vulnerability and uses web scripting to gain remote access.

Stage II:

Once the attacker has gained access, he or she further tries to obtain credentials of the compromised environment to move to other systems in that environment.

Stage III:

The attacker now modifies the registry to create a backdoor.

Stage IV:

The attacker gathers required data and copies it in one location. The attacker then uses readily available tools and compresses the data using the readily available system tools. And, the attacker then, finally removes the data from the environment by uploading it through FTP.

What Are The Various Different Types of Fileless Malware Attacks?

Let’s have a look at some types of Fileless Malware –

– Memory Code Injection –

As the name suggests, using this technique, an attacker hides malicious code in a legitimate application’s memory. The malware injects and distributes itself while the processes which are crucial to WIndows activity are running. Talking of legitimate applications, since it uses Windows programs like MWI and PowerShell, the commands that are executed are considered safe, and as such don’t trigger any red flags.

– Windows Registry Manipulation –

In the past, Powelike and Kovter transformed a victim’s system into a click bot and connected to click-through ads and websites. In this kind of attack, when a malicious link or file is clicked upon by a victim, the malware uses a normal Windows process to write and even execute a fileless code right into the registry.

– Script-Based Techniques-

Not saying that this technique is completely lifeless, but, one thing is for sure, it is not easy to detect. Let’s explain this with the help of two popular attacks – SamSam Ransomware and Operation Cobalt Kitty. While the former was semi-fileless. In this attack, the payload couldn’t be analyzed without the initial script as it was run-time decrypted. Plus, it also requires a password on the creator’s end. Talking of Operation Cobalt Kitty, it was a fileless attack that targeted an Asian corporation for nearly 6 months using malicious PowerShell. More specifically, a spear-phishing email was used to infiltrate over 40 servers and PCs.

How Can You Defend Your System Against files Malware?

A Fileless Malware is capable of defeating an Antivirus solution (( a weak one at that) but that doesn’t mean you shouldn’t have one on your computer. Most Antivirus solutions, including Microsoft’s Windows Security, are capable of thwarting irregular activities from PowerShell (if any). Below we are going to list some mindful steps that you should take so that you can steer clear of Fileless Malware as far as possible.

  • First and foremost, never click on suspicious links on any website. You shouldn’t visit websites that you don’t trust.
  • Update the various applications on your computer, especially the ones that come from Microsoft.
  • We recommend having two Antivirus protections. You can use Microsoft Defender and as a primary or second layer of Antivirus protection on your Windows operating system, you can opt for T9 Antivirus.

Here are some of the notable features of this Antivirus application –

  • Real-time protection against a variety of malicious threats.
  • Protection against PUP, zero-day threats, Trojan and More.
  • Removal of emerging vulnerabilities.
  • Multiple scans to remove threats.
  • Schedule scans at your desired time.
  • Exploit protection against unknown files.
  • You can wipe off unwanted startup items.
  • The Antivirus utility is lightweight.

How Does T9 Antivirus Work?

1. Download and install T9 Antivirus


2. Let the Antivirus install updates.


3. Click on the orange-colored SCAN NOW button.


4. T9 Antivirus will now look for any impending threats.


Wrapping Up

Malware can appear in various forms and intensities, and as we can see from Fileless Malware, the threat actors are constantly upping the ante so as to defeat defenses. So, it is important that we never ever keep our guard down, no matter who you are, a full-fledged business corporation or an individual. If you liked what you read, do give it a thumbs up and share it with your friends and everyone you care for.

Frequently Asked Questions

Q.1. What is an example of Fileless Malware?

Some of the notable examples of Fileless Malware include Code Red Worm (2001), SQL Slammer (2003), Operation Cobalt Kitty, Stuxnet (2010), UIWIX (2017), and Ramnit Banking Trojan.

Q.2. What are Fileless Viruses?

A Fileless Virus or Fileless Malware does not use traditional executable files to carry out the attack, instead, it turns your Windows computer against itself by exploiting the operating system and legitimate Windows applications.

Q.3. Are worms Fileless Malware?

The first-ever malware that was classified as Fileless Malware was Code Red Worm which went rampant in 2001. It attacked computers that ran Microsoft’s Internet Information Services (IIS). Another popular work that was memory-only malware was Duqu 2.0.

Q.4. Does Windows Defender detect Fileless Malware?

Microsoft has also upgraded Windows Defender in a way that it can detect irregular activities from a legitimate program like Windows PowerShell. Microsoft Defender comes with AntiMalware Scan Interface (AMSI, memory scanning, behavior monitoring, and boot sector protection. With the help of these, you can expect to thwart a Fileless Malware.

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