What is Fileless Malware?

What is Fileless Malware

Attackers use fileless malware to bypass virus scanners and signature-based detection systems, then take advantage of built-in functionality like Microsoft Office macros or administrative tools native to Windows OS such as WMI or PowerShell to launch attacks against systems they gain access to.

How Hackers Use Fileless Malware to Attack Your Organization?

Living-off-the-land allows hackers to avoid traditional security tools that analyze hardware. Furthermore, they can hide malicious code within small scripts disguised with keywords that appear legitimate to internal monitoring software.

What is Fileless Malware?

Fileless malware is often an efficient solution when it comes to stealing credentials, encrypting data or installing other forms of malicious software onto a system without altering a single file on its target computer. Fileless hacking techniques take advantage of existing programs and services running code rather than installing new malicious binaries onto one’s hard drive.

Signature-based antivirus and intrusion detection systems often struggle to identify and block attacks like this one because they target legitimate programs; since such attacks often go undetected for extended periods.

Add insult to injury by attackers employing various means of attack. Phishing emails might contain links or macros that trigger PowerShell commands to infiltrate a system; hackers might exploit a web application vulnerability and then hide their code inside an authorized program such as Windows Explorer or the kernel; they might also create user accounts or add autorun keys into Windows Registry in order to achieve persistence.

State, Local, Tribal and Territorial (SLTT) government entities can effectively protect themselves against these attacks by implementing an endpoint security solution with comprehensive defenses such as CIS Endpoint Security Services that can analyze endpoint behavior and detect anomalous activities. Furthermore, SLTTs should use network segmentation techniques, limit administrative privileges for users and enforce two-factor authentication to enhance protection.

How does a fileless Malware attack happen?

Cybercriminals who employ fileless attacks don’t need to copy any external binaries in order to launch them; rather, they can embed malicious scripts directly into native applications such as PowerShell which allow them to run entirely in memory, making it hard for internal monitoring software to raise an alarm.

Attacks can come via emails and malicious downloads or links that appear legitimate, then hackers use small scripts that go through memory to manipulate code to steal data, while at the same time being used as remote downloaders of more harmful files and to execute them remotely.

Hackers have used this capability to carry out multiple attacks such as information theft, ransomware infection, remote access trojans (RATs) and cryptominers – without writing any files on disk and thus bypassing signature-based detection mechanisms.

Therefore, it’s critical that security measures can detect this type of attack. You may wish to employ endpoint protection software like Carbon Black to monitor your network and detect attacks that regular antivirus software misses; thus preventing malware from spreading between systems. It also assists with disabling Office macros, patching vulnerable applications and providing behavior-based detection, keeping your environment as safe as possible.

Characteristics of Fileless Malware

Fileless malware refers to software that works in memory and therefore is undetectable by traditional antivirus systems. This new type of attack often leverages legitimate Windows system tools and applications like PowerShell or WMI in order to gain entry to an organization’s systems without their knowledge.

Attackers use techniques such as phishing emails and social engineering to manipulate employees into clicking attachments or links from unsuspicious sources. Once inside, hackers use tools to steal credentials, encrypt data or even take over systems by exploiting vulnerabilities and running various forms of malicious commands.

These attacks can be difficult to stop as they’re often concealed from anti-virus scanners and signature-based detection systems, and operate in memory so as to not get deleted when rebooting or shutting down your PC/server.

To protect against fileless threats, it’s essential that your cybersecurity strategy includes an effective threat hunting solution that can detect suspicious activities that could amplify a cyberattack when it strikes. Real-time threat hunting entails collecting, standardizing and acting upon bulk threat data to detect attacks, stop malicious activities and rectify processes that contribute to an attack – making this an essential component of cybersecurity strategy. Varonis offers comprehensive threat monitoring designed specifically to combat fileless attacks as well as other advanced threats.

Types of Fileless Malware Attacks

Hackers use fileless malware in various forms to attack organizations. Some methods are more advanced than others, yet all have one thing in common – they’re difficult to detect by conventional antivirus solutions and other endpoint security tools.

Hackers employ system tools like PowerShell and other Windows scripting languages such as ActiveScripting to perform attacks without leaving any traces behind, which provides numerous advantages. Threat actors find it easier to go undetected using tools trusted and widely utilized by system administrators; and by hiding their activity through modified command lines or running as legitimate processes they often evade detection altogether.

These attacks typically begin with an email phishing scam or some form of social engineering to gain entry to a device and once inside they can employ more advanced attacks methods.

To protect themselves against such attacks, enterprises require a new generation of endpoint protection designed to detect fileless malware. A solution combining threat intelligence and behavioral analytics can establish real-time baseline behavior of users and applications that allows for timely detection of abnormal and suspicious activities that have passed by traditional detection systems.

1. Memory Code Injection

Memory code injection is one of the most widely-used fileless malware attack techniques, enabling attackers to hide malicious code within legitimate programs like Windows Management Instrumentation and PowerShell or system tools like VBScript/JScript in order to bypass security controls and avoid detection by anti-virus solutions by inspecting files or searching signature databases; in addition, memory code injection also leaves little trace behind of its activity at an endpoint computer system.

This method begins by creating a new process to host malicious code in suspended mode, before calling VirtualAllocEx for space to write DLL paths before employing APIs such as NtCreateThreadEx or RtlCreateUserThread to create threads to execute it.

This type of attack is an excellent example of “living off the land”, an attack technique in which hackers leverage on-site systems to bypass security controls, bypass antivirus scanners and escape network intrusion prevention systems (NIDS). Companies should implement safeguards such as restricting remote applications for non-administrators users, enforcing two-factor authentication, and offering limited networking for average users in order to make it harder for hackers to live off the land.

2. Windows Registry Manipulation

Fileless attacks differ from file-based malware in that they use native Windows tools to execute their malicious code, thus making it harder for detection tools and antivirus software programs to identify them. Attackers typically distribute these tools as scripts through emails or links which appear safe, or through legitimate downloads and downloads that seem legitimate.

The Windows Registry, an integral part of operating systems running Microsoft Windows, contains an abundance of raw data which malicious actors can exploit to gain entry to victims’ environments or establish persistence by manipulating its time-shifting functionality (TimeStomping). It offers an opportunity for persistent attacks against systems as hackers can delete information from registry hives and even manipulate TimeStomping APIs to alter time change (TimeStomping).

As the registry is an essential component of a system, it is vital that any changes within this data structure be carefully monitored. Any unusual shifts that do not correspond with software patches, service start/restart cycles and other actions should raise suspicions and monitored closely to detect any attacks that have taken place. As an MS-ISAC member you can gain access to regular threat alerts and briefings covering cyber threats including fileless attacks as well as our indicator sharing program which ingestions and blocks indicators real time to protect against attacks targeting U.S. State Local Tribal Terriorean Terrior Terriean governments (SLTT).

Fileless Malware Is Harder For Cybersecurity Tools To Detect

Fileless malware can be harder for cybersecurity tools to identify as it doesn’t rely on malicious files for its attacks; rather, it hides within programs administrators trust instead.

Attackers commonly gain initial access to systems through phishing attacks with macros or other social engineering tactics, then using methods such as adding autorun keys to the Windows Registry in order to establish persistence.

How To Detect Fileless Malware Attacks?

Fileless attacks differ from traditional malware in that they do not rely on downloading external malicious binaries; rather, these types of hacks utilize existing software programs such as PowerShell to perform their operations. A hacker could embed a malicious script within it in order to gain unauthorized access to system resources and steal confidential data – one of the most dangerous types of hacking as it’s difficult to detect and remove.

Hackers frequently utilize email attachments with malicious macros or scripts from websites as the most prevalent method for spreading fileless malware, bypassing antivirus systems and even IPS systems in the process. Once downloaded, these scripts load directly into RAM memory before being remotely executed by attackers without detection by antivirus programs and even IPS systems.

Security teams need to utilize next-gen, fully managed threat hunting services that monitor an environment for indicators of compromise. Such tools utilize advanced memory analysis capabilities to detect malware or suspicious activities as well as vulnerabilities and gaps exploited by attackers when conducting fileless attacks.

1. Malware Gains Access to the Machine

First step of any malware attack: gain entry. This typically happens via phishing attacks or social engineering using malicious links that appear as legitimate business websites.

Fileless malware differs from file-based malware in that it doesn’t download to a computer and then write itself directly onto disk when executed, meaning it cannot be detected by traditional antivirus software or other security solutions that look for signs of malicious code, like heuristics.

Fileless attacks use malicious scripts inserted into existing applications on a machine, including native system files and software, such as WMI, Microsoft Office macros and PowerShell. This method has been employed successfully for over twenty years by attackers worldwide. It has come to be known as living-off-the-land attacks.

Security products find it much harder to detect and stop attacks that use tools that are native and often used for legitimate purposes, and this method makes exploit creation simpler for attackers as they combine these tools into complex cyberattack architectures.

2. The Program Establishes Persistence

Once fileless malware has gained entry to your system, its goal is to establish itself permanently. To achieve this end, it may add autorun keys or install executable files directly in memory – this way enabling attackers to execute commands without leaving footprints behind that can be detected by traditional antivirus solutions.

Hackers achieve persistence by injecting malicious code into legitimate, trusted applications. For example, hackers often employ Windows Management Instrumentation (WMI) and Microsoft PowerShell as means to remotely execute malware remotely – these tools being widely utilized among administrators themselves and being familiar to potential cyber criminals alike. Indeed, living off the land attacks typically involve threat actors exploiting already installed and trusted applications to conduct their attacks.

Hackers embed fileless malware within legitimate programs to commit harmful acts, such as stealing credentials or encrypting files. However, adopting the principle of least privilege and network segmentation can help combat such threats.

3. Data Exfiltration

Hackers have increasingly turned to script-based attacks using programs like PowerShell in order to subvert internal monitoring systems with malware. By exploiting trusted programs like this one, hackers have used script-based attacks as a covert means of passing malware without detection and whitelisting; hackers may hide malicious scripts inside common programs like Word or PDF documents or host fake websites that look legitimate.

Once a computer is compromised, hackers can quickly begin extracting data by using PowerShell commands to search for sensitive files and folders using PowerShell searches. When they find what they need they compress the file before uploading it onto a remote server for further exfiltration.

SentinelOne provides behavioral detection technology that uses sequences of events rather than individual files as the best way to detect fileless malware attacks in organizations, preventing adversaries from accessing your data by detecting activity that would not normally be triggered by user interactions. With AI detection combined with layers of security features that block macro documents, exploit kits, PowerShell scripts and zero day vulnerabilities without impacting employees productivity or productivity losses in an organization, SentinelOne offers complete protection from fileless attacks – request a demo today and discover how SentinelOne can protect you!

5 Common Fileless Malware Techniques

Fileless malware attacks don’t rely on files; rather, the malicious software resides in system memory and therefore may be harder to detect than other forms of malware. Heuristics and whitelisting won’t work because there are no typical file signatures.

Cybercriminals have increasingly adopted fileless malware techniques, with estimates showing PowerShell attacks rising by 43% year-on-year and other exploiters using script engines like VBScript for cyberattacks. Luckily, there are ways to counter such threats.

Attackers using these attack methods can use applications administrators would trust, such as Windows script programs, Windows Management Instrumentation (WMI), and PowerShell, to conceal their activities from administrators and use these tools for their attack life cycle functions like gaining access, establishing persistence, stealing data or destroying it.

One way to combat such threats is with a managed threat hunting service that constantly monitors an organization’s endpoints, flagging suspicious activity and helping to prevent attacks by identifying indicators used by attackers.

1. Memory-resident Malware

Fileless malware attacks use memory rather than programs to perform their harmful activity, providing attackers with another way of bypassing traditional cybersecurity mechanisms and evading detection or interruption mechanisms.

Hackers typically utilize compromised Flash and Java programs, browsers or phishing campaigns that contain infected links or attachments as vectors for injecting malware onto target systems. Attackers then leverage these compromised programs in order to gain entry.

Once a hacker gains entry, they may use various fileless techniques to steal data, commit other criminal acts and open backdoors that allow them to remotely control your computer. Attackers gain entry by exploiting vulnerabilities in trusted programs and employing techniques like memory code injection, process hollowing, Gargoyle (ROP/APC) manipulation or Windows Registry manipulation. Cybereason Nocturnus team recently observed Spelevo Exploit Kit exploiting Windows Registry to successfully execute its payload and steal cryptocurrency, bypassing detection systems such as virus scanners or signature-based endpoint protection solutions like Varonis. This tactic provides attackers an effective means of bypassing those measures.

2. Rootkits

Fileless malware makes cyberattacks possible by hiding malicious code in programs you already trust on your computer, such as Windows script applications and PowerShell. Hackers use these trusted applications to remotely load malicious scripts that steal or damage data on their target computers.

Fileless attacks offer numerous advantages over their software counterparts, such as bypassing heuristic scanners and being harder to detect than files or software viruses. Furthermore, fileless attacks may operate inside containers making detection even harder for security tools.

Attacks against computers have long been part of history, including 20 MB Flame malware that caused widespread disruptions in 2012 and LoJax, the first rootkit to exploit UEFI firmware (software that emulates physical computers on motherboards) to gain entry and survive an OS reinstall. Recently, we’ve seen cryptocurrency mining and automated clickbaiting attacks used to increase YouTube revenue or subscribers gain prominence as attack techniques.

3. Windows Registry Malware

The Windows Registry is a hierarchical database that stores configuration details for various programs and apps, providing hackers and attackers a way to conceal malicious code that will run unnoticed by antivirus (AV) software or other security controls.

Kovter malware uses DLL Search Order Hijacking to gain persistence by adding itself as an entry in AppInit_DLLs section of Registry, so it will execute each time someone logs in or until victim logs off or system shuts down.

As such, attackers can circumvent AV detection and hide their activity within volatile memory, making it harder for antivirus programs to detect. This method is particularly harmful when dealing with ransomware attacks that encrypt victim files before demanding payment in exchange for decryption keys. Luckily, most ransomware attacks don’t employ fileless methods but it is wise to be vigilant and watch for suspicious activity on endpoints such as unexpected deletion of Windows Registry entries as this could indicate malicious code is hiding there.

3. Windows Registry Malware

Registry malware is one of the most prevalent fileless threats, taking advantage of your system software, applications, and protocols to install and execute malicious activities on your system. Registry malware usually operates by altering your Windows Registry – an online database which stores system configuration settings – with this modification leaving no traces such as files or system changes behind for detection purposes. Kovter, GootKit, Poweliks and Duqu are just some examples of programs which manipulate it effectively.

Hackers spread malicious scripts via phishing attacks, fake download links and watering holes that look legitimate. Once inside, hackers use tools such as Microsoft PowerShell and WMI to access other parts of the system and bypass internal monitoring software. Hackers may alter HKLM root key ImagePath/binPath values in order to point towards programs which launch automatically at Windows startup or hide remote access Trojans (RATs). When reviewing your telemetry data, keep an eye out for unexpected changes to these keys.

5. Exploit Kits

Attackers use exploit kits to launch fileless malware attacks. Contained within these kits is everything necessary for compromised a system quickly, targeting tools trusted by users such as PowerShell and Office. Once an exploit kit has made contact with its host environment, it can bypass traditional security responses like anti-virus scanners and network firewalls.

Threat actors can insert malicious code into legitimate applications and hijack them to remotely launch and execute commands, code sequences and scripts that run in memory. This method goes undetected by traditional security programs since it doesn’t rely on files or leave any trace in memory.

Once inside, threat actors use social engineering schemes and password-cracking tools to gain remote control of an environment and take over its control, giving them remote access. Once they do so, they can begin performing activities like extracting compressed data for exfiltration; encryption or theft for ransomware ransom; as well as extracting confidential information for ransomware use – detection requires combining prevention with memory forensics and advanced analytics solutions.

Fileless Malware – Harder to Detect Than Traditional Viruses

Fileless malware attacks can be difficult to spot. They typically hide within legitimate programs like PowerShell that run solely in memory, bypassing firewalls and antivirus scanners altogether.

SLTTs must take proactive steps to ward off fileless attacks, such as using behavioral analysis which focuses on indicators of compromise rather than simply looking for malicious activity.

Final Thoughts

Fileless malware may seem impossible to spot, but with proper security solutions it can be easily avoided. Updating software patches regularly, warning employees about suspicious links in emails and websites and installing an antimalware solution with AI detection all provide vital protections against fileless threats.

This type of attack involves inserting malicious code into legitimate programs such as Flash, Java or the browser and then executing it in memory. Additionally, vulnerabilities in other software running on a computer – Adobe Reader or Microsoft Word for instance – could also be exploited to gain entry to networks.

Hackers have the ability to carry out all of the usual file-based malware attacks using this method, including encrypting data and threatening deletion without payment in cryptocurrency. As such, this form of attack has gained increasing popularity with hackers and should be taken very seriously by companies. There are strategies available for protecting against this form of attack such as hardware verification, pattern-analysis/signature detection detection as well as time stamping to address these threats.

Sam is an experienced information security specialist who works with enterprises to mature and improve their enterprise security programs. Previously, he worked as a security news reporter.