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November 23, 2023

What is Fileless Malware? How to Protect Against Fileless Malware?

What Is Fileless Malwarehow Does Fileless Malware Work And How To Protect Against Fileless Malware

Computers have always been vulnerable to malicious software. Like any other cyber threat, it has improved in potency and efficiency over time. Malware that doesnt create a file is one of the most dangerous types of malware. For the first half of 2020, it has been named the most prevalent critical-severity cybersecurity threat to endpoints.

The most dangerous aspect of fileless malware is how it hijacks a users machine by hiding in RAM and then using the users software and programs against them. In addition to being undetectable by standard means, it has no recognizable code or signature, making it even more dangerous.

In this blog post, we will talk about what is fileless malware, how does fileless malware work and why its become a widespread attack method with cybercriminals. Well also explain how to protect against fileless malware and keep your data safe. So if you want to stay ahead of the game regarding cybersecurity threats, read on!

What is Fileless Malware?

The term fileless malware refers to dangerous software that may penetrate your system without needing a specific file. Not all malware, like viruses, behaves this way. Essentially, malicious actors embed fileless malware into legitimate apps and use them to carry out malicious deeds.

One method by which these assaults function is by inserting harmful code into programs with which your computer already comes equipped. Phishing and other forms of social engineering are valuable tools for this purpose. Once the malicious code has been integrated into a trusted program, it can spread laterally throughout your network in search of additional sensitive data.

In most cases, the motivation behind fileless malware assaults is financial or reputational. Since fileless malware is memory-based and lacks a signature like file-based malware like adware, it can be challenging to eradicate.

Businesses, especially those that operate solely online, have been vulnerable to cybercrime for as long as the internet has been around. The frightening worldwide cost of the cybercrime in 2022 was $6 trillion. As a result, businesses must educate their employees about cyber threats such as malware, phishing, scams, etc.

Characteristics of Fileless Malware

After knowing what is fileless malware, it is important to discuss its characteristics. Below are some characteristics of fileless malware: 

  1. Fileless malware has no detectable code or signature that standard antivirus technologies may use to locate it in a computer system. Because it does not exhibit any particular behavior, heuristics scanners cannot identify it as malicious software.

  2. Fileless malware is present in the random access memory of your machine. Memory-based malware is another name for this type of malicious software.

  3. To carry out the assault, use processes indigenous to the operating system you are working with.

  4. It can offer possible combinations with other forms of malicious software.

  5. Its possible that youll be able to get around application whitelisting, which is a method that ensures only authorized apps may be installed on a computer. Malware without files might infect your computer by exploiting legitimate programs that are already installed on it.

Example of Recent Fileless Malware Attacks

Fileless malware is a growing threat used by attackers to silently infiltrate systems without leaving any trace of malicious files. These attacks are often difficult to detect and can cause significant damage, making them especially dangerous. 


One example of a recent fileless malware attack targeted the U.S. Department of Defense in June 2019. The attack was carried out using spear-phishing emails containing malicious links or attachments sent to unsuspecting victims. Once clicked, the link or attachment would execute a PowerShell script which allowed attackers to gain access to the organizations networks and then install backdoors that enabled further attacks against other systems and data theft. 


The second example of fileless malware was discovered in early 2020 as part of the IcedID banking trojan campaign. In this attack, attackers used a combination of phishing emails and malicious links to deliver the fileless payload. Once clicked, the malicious link would download an executable that would inject code into memory and execute it without writing files on the disk.


Another example of a lifeless assault is

, which targeted an Asian company with malicious PowerShell for over six months. The attack lasted almost that long. More than 40 computers and servers were compromised through a spear-phishing email.

How Does Fileless Malware Work?

Weve discussed in detail what is fileless malware along with some recent examples, now, lets look at how does fileless malware work: 

Malware that does not save itself in a file or installs itself on your device might carry out its malicious activity in the systems memory. Hackers carry out the most destructive acts using the task-automating program Microsoft Windows PowerShell.

Fileless malware does not need a cybercriminal to install harmful code onto a victims machine since it is not based on files but on memory. File-based malware, on the other hand, does. Instead, malicious actors take use of vulnerabilities included in native tools to carry out instructions, code sequences, and other operations that are carried out in memory.

Phishing emails, in which users are tricked into clicking on or downloading a malicious link or attachment, are the typical vector by which this type of malware spreads. 

Malware can also inject or embed straight into apps that have already been installed and other authorized programs. This is because standard security solutions often only examine files and not memory in search of abnormalities that might indicate the presence of malware.

How Does Fileless Malware Spread?

Fileless malware can spread in a few ways. For example, it can sometimes be embedded in software applications or exploit kits. These malicious programs are designed to exploit security vulnerabilities and launch attacks without the users knowledge. 

Fileless malware is also sometimes distributed via phishing emails containing malicious URLs. This type of attack works by enticing the user to click on a link that leads to malicious code downloaded and executed without the users knowledge. 

Additionally, fileless malware can spread through social media messages containing malicious links and hidden code attachments. Users need to be extra vigilant when clicking on unfamiliar links or downloading suspicious files, as cybercriminals use standard methods for spreading fileless malware.

The following is a breakdown of the four steps often occurring during a fileless malware assault.

The following is a breakdown of the four steps often occurring during a fileless malware assault.

  1. Cybercriminals Get Remote Access: An exploit using fileless malware is started by a threat actor in the same way that other intrusions are: by gaining a foothold in the victims system.

  2. Obtaining Credentials: Once they have gained remote access, they use various techniques to steal the credentials of the environment that has been infiltrated. Because of this, they can navigate the system more freely and take advantage of fileless malware to achieve their goal.

  3. Show Perseverance: The cyber actors then alter the parameters to provide a backdoor that would allow them to return to the environment without having to repeat the processes that came before.

  4. Exploitation and Escape of Data: In the final step, the hackers either steal or intercept the compressed data and get ready to exfiltrate it. They could even encrypt the data to launch a ransomware attack.

How to Detect Fileless Malware?

The first thing to bear in mind while trying to figure out how to protect against fileless malware assaults is that traditional antivirus software might not be effective. In addition, strategies such as sandboxing and whitelisting will not be successful in any way. 

This is partly due to the absence of a usual file signature that can be recognized and mitigated by the programs that make up these defenses.

A fileless malware assault can be recognized in several different ways, including the following:

Instead of using indicators of compromise, you should use indicators of attack

The search for indications of attack, often known as IOAs, is an efficient method for locating fileless malware. Because you can detect the behavior that is related to the virus rather than a specific file that has been delivered to your computer, this is the case. 

Analyzing indications of compromise (IOCs) is not the same as this since you are not hunting for suspicious files; you are monitoring your system for behavior that is not typical.

Irregular code execution and lateral motions are two instances of behavior that might be considered suspicious. Lateral movements are when malicious malware moves from one component of your network to another once it has successfully breached.

By examining these components of an assault, you are concentrating on the behavior of the malware rather than the file signatures that, for instance, may signal the existence of a conventional virus.

Utilize a Managed Hunting System for Threats

Managed threat hunting relieves you of the burdensome effort of locating and eliminating risks by doing it on your behalf. Instead of searching your computer system for fileless malware, you hire a knowledgeable organization to discover and stop it. 

In addition to this, you may make use of a managed threat-hunting service to do continuous monitoring of your system. They can immediately report any suspicious behavior and take action in response to it because of this system.

How to Protect Against Fileless Malware?

Your database and brand image can be protected against malware assaults like fileless malware if preventative measures are taken on purpose. Here are a few pointers that might help you avoid falling victim to fileless malware attacks.

Activate just the necessary tools

Except in cases when they are indispensable, you should turn off PowerShell, Windows System Instrumentation, and macros whenever you use a Windows computer. These three are official Microsoft offerings but are also the most susceptible to fileless assaults.

Try using the “principle of least privilege.”

The principle of least privilege dictates that access to a file should be limited to those with a legitimate business need to see it. Workers at lower levels, for instance, who are simply responsible for data input, may not require access to administrative tools.

Protection Against Phishing

Maintaining a secure system is the most effective measure to protect yourself from fileless malware assaults. Do not download files or click on any links in any emails you receive if you observe any phishing indicators.

  • An unexpected welcome from someone who frequently communicates with you via email.

  • Emails that provide a feeling of immediacy through using terms such as immediately.

  • Requests that are out of the ordinary, such as requesting login credentials (even if they seem legitimate).

Check the data flow on your network

This has more to do with detection than fileless malware security, but you should still keep an eye on your networks traffic to see if there are any unexpected surges. These hiccups may signify that an outsider accessed one of your companys computers.

Sessions of Education and Conscience-Raising for Employees

Regular training sessions for staff on the best ways to protect themselves from fileless malware, ransomware, spyware, and other online threats may go a long way. Lack of awareness on the part of employees is responsible for the majority of successful cyberattacks.

Ensure that all of your electronic gadgets are up-to-date

It would be best if you didnt skip over or dismiss update notifications or pop-ups on your screen. In most cases, upgraded versions have improved codes that can better defend against new methods of getting into a system. Malware attacks are more likely to succeed on programs and operating systems that have an older version.

Think about using a third-party service

An increasing number of third-party companies promise to give security even though antivirus products arent particularly successful at detecting or blocking fileless assaults. Carry out some study.

Bottom Line

To deal with fileless malware, it is first important to know what is fileless malware and how does fileless malware works, which our blog might have helped you know in detail. The fact that this malicious software can infect your computer without dropping any files on your system. This makes it difficult to detect and remove. 

The best way to protect against fileless malware is to use a good antivirus program and keep your operating system and other software up to date. It would be best if you also were careful of what you click on and what websites you visit. If you think you have been infected with fileless malware, you should scan your system with an anti-malware program and then take the necessary steps. 

We hope this post would help you know what is fileless malware, how does fileless malware work, and why its become a widespread attack method with cybercriminals. Well also explain how to protect against fileless malware and keep your data safe. Please share this post and help to secure the digital world. Visit our social media page on Facebook, LinkedIn, Twitter, Telegram, Tumblr, Medium & Instagram, and subscribe to receive updates like this. 

Arun KL

Arun KL is a cybersecurity professional with 15+ years of experience in IT infrastructure, cloud security, vulnerability management, Penetration Testing, security operations, and incident response. He is adept at designing and implementing robust security solutions to safeguard systems and data. Arun holds multiple industry certifications including CCNA, CCNA Security, RHCE, CEH, and AWS Security.

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