Fileless malware is an invisible threat that traditional security tools cannot detect. It may enter your system through exploits, compromised hardware, or regular execution of applications and scripts.
These attacks are persistent and difficult to eradicate. They also employ lateral movement--behavior that circumvents signatures, rules, and scans.
What is Fileless Malware?
Fileless malware differs from traditional malware in that it never writes to disk, instead running code within the system's memory. This makes it difficult for antivirus software and other security solutions to detect.
Hackers and cybercriminals increasingly rely on fileless malware to launch attacks due to its stealthiness, which can go undetected by signature-based antivirus software or intrusion detection systems, making it easier for them to obtain sensitive information and cause destruction.
Therefore, protecting your organization against fileless malware is of the utmost importance. One of the best ways to do this is by implementing behavior-based technologies that detect threats before they enter your network.
Another strategy is to educate your employees about phishing and other malicious activities that could lead to an infection. This includes recognizing suspicious emails, asking people not to click on links or attachments, and offering regular training sessions.
Furthermore, network segmentation and stringent access controls can help contain the spread of fileless malware. By restricting user access only to what is necessary for their job responsibilities, these strategies reduce the impact of these attacks on your business.
Common Fileless Malware Techniques
Fileless malware is a relatively recent hacking technique often undetected by traditional security solutions. This is because fileless malware doesn't rely on files or installation processes to install itself on a computer; rather, it operates entirely within memory.
One common technique is "packing," which involves encrypting code in a package and distributing it in memory without writing any data to disks. This enables malware to hide its true API and functionality and run malicious code without detection.
Another technique is known as "local code injection." This involves hiding malicious codes within legitimate applications already running on a system, giving hackers remote execution capability and access to sensitive information.
Other techniques involve phishing emails and links that appear legitimate as points of entry but contain malicious scripts running in memory. These scripts can be used to install malware, steal confidential information and even turn an infected machine into a click bot for online advertisem*nts.
Exploit kits
Exploit kits are collections of exploits that attackers can use to remotely compromise and run malware on a victim's system without relying on file-based delivery. These kits are highly adaptive and automated, making them one of the hackers' go-to strategies for large-scale malware distribution.
These tools allow hackers to take advantage of pre existing vulnerabilities in software, often without users knowing about it. This enables them to target a larger number of systems with less time and effort than would be required using traditional techniques.
Exploit kits typically contain multiple vulnerabilities, including those in web browsers, operating systems, and software programs. Furthermore, they may come equipped with a management console that gives the attacker complete control over their attack.
To launch an exploit kit, attackers must gain access to a compromised website with high traffic. The compromised site then redirects traffic toward a landing page containing code that scans for browser-based applications and operating systems vulnerabilities that can then be exploited.
Hijacked native tools
Fileless malware, also known as zero-footprint attacks, operates without the need for file downloads to execute malicious scripts. It does this by piggybacking on legitimate software packages and residing in random access memory (RAM) rather than on the hard drive, making detection and remediation extremely challenging.
Fileless malware can steal credentials, perform lateral movement across networks, and download additional viruses as the attack progresses. Furthermore, it has been known to contain rootkits - an extremely dangerous risk for businesses.
Hijacked Native Tools -- Hackers can hijack legitimate, trusted applications such as Word or JavaScript to install malware. These programs can be accessed remotely and run code without admin approval, giving hackers complete control over a program's functionality.
Cybercriminals can utilize tools like PowerShell to circumvent the built-in security features on a computer system. This enables them to launch attacks such as ransomware or banking trojans without leaving behind any security signatures.
OS Independent -- While Windows systems are the most common targets for fileless malware attacks, Mac and Linux computers may also be at risk. No matter which operating system a victim uses, these attacks can occur when a script is launched from a Mac or commands are executed remotely from an external server.
Registry resident malware
Registry resident malware is an extremely prevalent form of fileless cybercrime, infecting the Windows registry to remain undetected and persistent.
Detecting and removing Fileless malware can be difficult. Behavioral monitoring is one effective approach, though many variants remain persistent after reboot or RAM flush.
The malicious code resides in the Windows registry and activates automatically whenever you launch the operating system, making detection virtually impossible.
Fileless malware attacks typically target various vulnerabilities in popular applications and systems to launch an attack. Attackers often employ social engineering techniques to convince victims to download an infected attachment or open an infected link.
They then employ an exploit kit to scan for and exploit these vulnerabilities, often gaining total control of the device.
The primary advantage of fileless malware is its lack of dependence on downloads or viruses to infect a computer. Instead, it uses pre existing programs and tools built into a system - including native and highly trusted applications like PowerShell.
Memory-only malware
Memory-only malware refers to any program or process that does not write any data to the device's hard drive, helping it avoid antivirus software that employs file-based whitelisting, signature detection, hardware verification, pattern analysis, and timestamping, among other techniques for detecting malicious activity on computers.
This technique is typically combined with other malware, such as worms and ransomware. In a typical ransomware attack, hackers embed code in documents using exploit kits and inject that code directly into the machine's memory to encrypt important files and demand payment for its release.
Many antivirus programs also feature RAM scanning capabilities that can quickly and accurately identify suspicious activities on a target machine. Rebooting the device back to its factory defaults will remove any remaining memory-based malware from its system.
Memory-only malware is also notoriously difficult for digital forensics analysts to detect. This is due to its minimal evidence trail, making it a daunting challenge for the average Joe to detect an infection. The most effective way to prevent this type of outbreak is to implement an integrated security strategy that includes endpoint protection solutions, employee training, and proactive protection of network assets while recognizing potential threats early on.
Fileless Malware and Ransomware Security
Fileless ransomware is an emerging type of malicious software that conceals itself using trusted tools system administrators normally rely on, such as Windows scripting tools and PowerShell.
Cybercriminals use fileless malware to circumvent security systems, steal data and encrypt files with ransom payments to remain undetected and maintain persistence. This technique enables them to continue operating undetected for extended periods.
Traditional ransomware must be stored on a computer's hard drive to be detected, but fileless malware can be written directly into a victim's memory without access to the disk. This allows it to bypass antivirus and other security products, which only detect ransomware if it can access your hard drive.
According to the Ponemon Institute, fileless malware threats increased by more than 94 percent in the first half of 2018, signaling hackers' continued development of sophisticated techniques for circumventing defenses and creating an array of threats, including more distinct ransomware payloads.
How to Detect Fileless Malware?
Fileless malware is a modern type of malicious software that doesn't store its body on disk; rather, it resides in random access memory (RAM) without leaving behind any traditional signs of its presence.
Malware of this type typically enters computers through phishing emails or social engineering techniques, injecting itself into pre-installed applications or other legitimate programs so cybercriminals can remotely infiltrate systems.
Although detecting these attacks can be challenging, it's possible with specialized endpoint protection solutions that scan and mitigate fileless malware. Furthermore, applying the principle of least privilege and employing network segmentation within your organization are practical measures.
Eset EDR
