Fileless malware uses a computer system\u2019s built-in tools to execute a cyberattack. In other words, fileless malware takes advantage of the vulnerabilities present in installed software to facilitate an attack. This type of malware does not require the attacker to sneak malicious code onto a potential victim\u2019s system\u2019s hard drive to be successful. Therefore, fileless malware can be extremely hard to detect\u2014and extremely dangerous.<\/p>\n
This blog will outline the basics of what fileless malware is along with the stages of an attack, the common techniques used by cybercriminals employing fileless malware, and tips for detecting these types of threats.<\/p>\n
Fileless malware<\/a>\u00a0is a threat that doesn\u2019t exist on disk. Typically, when malware is on disk\u2014what I mean by on disk, is malware loaded onto a machine\u2019s SSD (solid state drive) or hard drive\u2014and it physically exists, it\u2019s much easier to detect by security software. Also, it can be examined by security researchers, especially if it\u2019s a complex threat.<\/p>\n Obviously, attackers don\u2019t want their malware to be analyzed by defenders, who would then be better able to defend by reverse engineering the malware. So, the best way for the bad guys to keep their fileless malware effective and not have it analyzed is to make sure it\u2019s not on disk. Hence, the rise of fileless malware.<\/p>\n Naturally, your next question about fileless malware is \u201cWhere in the world does it exist if it\u2019s not on disk?\u201d Basically, it exists in memory. Over the years, sophisticated attackers have used a variety of techniques to inject memory with their vilest malware.<\/p>\n Frodo and The Dark Avenger<\/a>\u00a0are early examples of fileless malware. Frodo was created in 1989 and was initially mean to be \u201ca harmless prank.\u201d Eventually, it that was exploited. That same year, The Dark Avenger was also discovered. It\u2019s a type of attack that was used to infect executable files every time they were run on an infected computer. Even the copied files would get infected.<\/p>\n Today, fileless malware has become so advanced that the code they inject in memory executes and downloads new code in memory. Fileless malware does not required files to launch, however, it does need to modify the native environment and tools that it tries to attack. This is a much more advanced way of using fileless malware.<\/p>\n Using this technique to execute makes it very difficult for security software to figure out what the fileless malware is executing because there\u2019s so many things happening in memory\u2014so many normal operations that are being run\u2014that it\u2019s complex and hard to examine and get a handle on what\u2019s happening. Security solutions simply can\u2019t get a baseline on whether something malicious is occurring or not. This is what makes fileless malware very effective.<\/p>\n We are seeing more than in the recent past, but one of the downsides for attackers trying to use fileless malware is that it is more complicated than traditional malware. To create and execute fileless malware, attackers require a higher level of skills. This is why when you do see fileless malware attacks, they are typically associated with state-sponsored threats or the most sophisticated cybercriminals.<\/p>\n To get the same capabilities and features that traditional malware have, fileless malware requires creators with strong skill sets. The challenge for them is that there\u2019s limited space in a device\u2019s memory and they don’t have much disk space to work with. The malware in memory can only reside in an existing memory space that’s already limited in functionality.<\/p>\n Fileless malware is not only difficult to execute, but attackers must find a place in memory for it. And this must work quickly because fileless malware is flushed from memory when the system is rebooted. To be effective, fileless malware attackers need the right set of circumstances.<\/p>\n Like a traditional malware attack, the typical stages of a fileless malware attack are:<\/p>\n Cybercriminals that use fileless malware need to access the system in order to modify the native tools and launch attacks. Currently,\u00a0stolen credentials<\/a>\u00a0are still the most common technique that attackers use to gain access.<\/p>\n Anytime you hear about credentials being stolen or usernames being hacked or credit card information being lifted, I wouldn’t be surprised if there’s at least some component of fileless malware involved.<\/p>\n Once fileless malware has gained access to a system, it can begin launching traditional malware. The techniques listed below tend to be more successful when combined with fileless malware:<\/p>\n The best way to detect and defeat fileless malware attacks is to have a holistic approach with a multi-layered defense posture. An organization\u2019s best practices for detecting fileless malware threats should include employing indicators of attack (IOAs) along with indicators of compromise (IOCs) and leveraging their security solution\u2019s threat hunting capabilities.<\/p>\n Because fileless malware uses a system\u2019s built-in tools to facilitate attacks and cover its tracks, cybersecurity teams must be aware, remain vigilant, and know the different methods attackers employ in carrying out these fileless malware attacks. It\u2019s all about gaining visibility on cybercriminals that are trying hard to hide in a system\u2019s memory.<\/p>\n By\u00a0If Fileless Malware Is Not on Disk, Then Where Is It?<\/h2>\n
If It\u2019s so Effective, Why Don\u2019t We See More Fileless Malware Attacks?<\/h2>\n
What are the Stages of a Fileless Malware Attack?<\/h2>\n
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What is the Most Common Fileless Malware Technique?<\/h2>\n
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How Do You Detect Fileless Malware?<\/h2>\n