Unlike traditional malware that relies on files and executable code to infiltrate systems, fileless malware operates directly within the memory, exploiting legitimate tools and processes to execute its malicious payloads.
With their ability to operate stealthily in memory, fileless attacks have been renowned for their mysterious techniques and their potential to bypass traditional security measures.
Let’s delve into the intriguing world of cyber threats and explore the arena of fileless attacks!
What is a Fileless Malware?
Fileless malware, also known as memory-based or non-malware attacks, is a type of malicious cyber attack that operates without leaving traces of files on the victim’s disk. It aims to exploit vulnerabilities in software, scripts, or operating systems to inject malicious code directly into the memory, evading traditional antivirus and detection mechanisms that primarily focus on file-based threats. This type of malware exclusively resides and operates within the volatile memory (RAM) of the compromised system, making its detection and eradication more challenging.
Feature of a Fileless Virus
- Leverages Legitimate Tools: It exploits trusted programs like PowerShell or document macros to execute malicious code, making it appear like normal activity.
- Lives in Memory: It operates primarily in memory, avoiding disk storage and traditional file-scanning detection methods.
- Evasive and Stealthy: It lacks a permanent file footprint, making signature-based detection difficult and allowing it to evade traditional security measures.
- Persistence Mechanisms: It can establish persistence by manipulating system settings to ensure it remains active even after a reboot.
- Lateral Movement: Once established on a system, fileless malware can leverage its access to move laterally across the network.
The Ponemon Institute has estimated that the success rate of fileless attacks is approximately 10 times higher compared to file-based attacks. This highlights the rising significance of fileless malware as a prominent threat in the cybersecurity landscape. Organisations must adopt necessary security solutions specifically designed to identify and mitigate these evolving threats.
What is the difference between a fileless and a file-based attack? The main difference between fileless and file-based attacks lies in their execution and detection methods.
- File-based malware relies on executable files that are stored on disks, while fileless malware operates in memory without leaving persistent files, making it harder to detect and remove.
- File-based malware typically utilises executable files, while fileless malware exploits trusted processes and scripts.
- File-based malware can be automated by executing malicious files, while fileless malware leverages existing system components to carry out its malicious activities.
Types of Fileless malware and its examples
Memory-only malware:
This type of malware exists only in the memory of a computer and doesn’t write itself to disk. This makes it difficult to detect because it disappears when the computer is rebooted.
Example: Powelike
Poweliks is a fileless malware that utilises JavaScript or VBScript embedded in malicious email attachments or compromised websites to infect systems. Once executed, Poweliks employs PowerShell to inject its malicious code into legitimate processes, making recognising challenging. It is known for its ability to download additional payloads or perform various malicious activities, such as data theft or remote access.
Windows Registry malware:
This type of malware stores itself in the Windows Registry, which is a database that stores settings for the operating system. This can be difficult to identify because the malware can be disguised as legitimate registry entries.
Example: Kovter:
Kovter is a fileless click-fraud malware that primarily targets advertising networks. It infiltrates systems through malicious email attachments or exploit kits. Kovter operates solely in memory, utilising window registry keys for persistence. It hijacks web browsers to simulate legitimate clicks on advertisements, generating revenue for the attackers without the user’s knowledge.
Also Read: How Can You Avoid Downloading Malicious Codes?
Fileless ransomware:
This is a type of ransomware that encrypts files without ever being written to disk. This makes it more difficult to detect and prevent than traditional ransomware.
Example: Emotet
Originally known as a banking Trojan, Emotet has evolved into a fileless malware variant. It spreads through spam emails and malicious attachments. Once executed, Emotet employs macros embedded in Office documents to initiate the infection process. It establishes persistence on the compromised system and can download additional payloads, such as banking Trojans or ransomware.
Macro malware:
This type of fileless malware is embedded in macros, which are small programs that can be attached to documents or spreadsheets. When a macro is enabled, it can run malicious code that can infect the computer.
Example: Dridex
Dridex is a notorious banking Trojan that has incorporated fileless techniques into its attack arsenal. It primarily spreads through malicious email attachments, often disguised as invoices or financial documents. Once executed, Dridex employs macros to download and execute its payload directly in memory, allowing it to evade traditional file-based detection methods.
What is the origin of all fileless malware?
The origin of fileless malware can be traced back to advancements in cybersecurity technologies and the evolving tactics employed by cybercriminals. As traditional security measures improved in detecting and blocking file-based malware, attackers began exploiting legitimate processes, scripts, and memory-based techniques to carry out their malicious moves without relying on persistent files.
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How does a fileless malware work?
Fileless malware operates uniquely to carry out malicious activities while evading many security solutions and hindering forensic analysis. Unlike traditional viruses, fileless malware resides exclusively in a computer’s memory.
Fileless malware commonly exploits Microsoft Windows PowerShell, a legitimate tool for system administration and automation. Attackers use PowerShell’s command-line shell and scripting language to deeply infiltrate Windows systems without leaving typical file-based traces. They employ social engineering tactics to gain initial access discreetly and progress through different stages.
What are the stages of a fileless attack?
Fileless attacks follow a series of stages, each with its techniques and objectives. These stages outlined below demonstrate how fileless attacks can unfold, highlighting the use of various techniques to gain access, maintain persistence, and exfiltrate data.
Stage 1: Initial Access
Technique: Exploiting vulnerabilities or leveraging web scripting for remote access.
The attack often begins with a phishing email containing a malicious link or attachment. When the victim clicks the link or opens the attachment, it triggers a script (often JavaScript, VBScript, or PowerShell) that runs directly in memory.
Stage 2: Credential Theft
Technique: Exploiting vulnerabilities or using tools like Mimikatz to steal credentials.
Once inside the system, the attacker focuses on acquiring credentials for the compromised environment. By leveraging the access gained in the previous stage, they aim to obtain usernames, passwords, or other authentication details. These credentials allow the attacker to move laterally within the environment and access additional systems.
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Stage 3: Persistence
Technique: Modifying the system’s registry to establish a backdoor.
To maintain a long-term presence within the compromised environment, the attacker modifies the system’s registry. This modification creates a backdoor, ensuring they can re-enter the system easily without repeating the initial stages of the attack. Techniques like the Sticky Keys Bypass may be employed to achieve persistence.
How does filesless malware achieve persistence?
Fileless malware achieves persistence by modifying the system’s registry, creating or modifying scheduled tasks, installing itself as a service, leveraging trusted binaries and scripts, injecting code into memory, and using PowerShell. These techniques allow the malware to maintain a presence within the compromised system without relying on traditional file-based mechanisms, making it harder to detect and remove.
Stage 4: Data Exfiltration
Technique: Utilising the file system and built-in compression utilities, followed by data upload via FTP or other means.
In the final stage, the attacker collects the desired data and prepares it for exfiltration. They may gather the data from various locations using the file system and leverage built-in compression utilities like Compact to compress the data. Once prepared, the attacker removes the data from the victim’s environment by uploading it via FTP or other methods, effectively exfiltrating the stolen information.
By operating solely in memory, fileless attacks can present significant challenges in detection and mitigation, making them a potent threat to target systems.
Invest in advanced security solutions, which utilise behaviour-based detection mechanisms to identify suspicious activities and anomalies associated with file-less attacks.
How to detect fileless malware attacks?
There are several techniques and best practices you can employ to help identify and mitigate fileless malware attacks. Here are some recommendations:
- Conduct regular security audits to identify vulnerabilities that could be exploited by fileless malware.
- Monitor process behaviour for unusual activities like code injection or unauthorised network connections.
- Perform memory analysis to identify malicious code or payloads in memory.
- Monitor network traffic for suspicious patterns or connections to command-and-control infrastructure.
- Utilise user behaviour analytics to identify deviations from normal patterns.
- Keep systems and software up to date with patches and perform regular vulnerability scanning.
- Educate employees about fileless malware and promote cautious online behaviour.
- Deploy a Security Information and Event Management (SIEM) solution for event correlation.
- Leverage behavioural analysis and machine learning to detect suspicious activities.
- Develop and regularly test an incident response plan specific to fileless malware attacks.
How do I know if my computer has malware?
Signs of malware on your computer include slow performance, unexpected pop-ups, unexplained system crashes, excessive network activity, and changes in browser settings or the homepage. Additionally, if you notice unfamiliar programs or files, disabled antivirus software, or unauthorised access to your personal information, it may indicate malware presence.
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How to prevent fileless attacks?
Preventing fileless attacks requires implementing effective security measures. Here are some steps you can take:
- Update all systems, software, and applications with the latest security patches to mitigate vulnerabilities that fileless malware may exploit.
- Conduct regular network vulnerability assessments to identify and address vulnerabilities across your network infrastructure.
- Employ advanced endpoint security tools that use behavioural analysis and machine learning to detect unusual patterns indicative of fileless malware activity.
- Educate people about the perils of fileless attacks and train them in safe computer practices.
- Use advanced email security solutions, such as spam filters, email authentication protocols and sandboxing, to detect and block phishing emails delivering fileless malware payloads.
- Enable multi-factor authentication (MFA) to provide additional security to user accounts.
- Segment your network to protect vital systems and reduce the effect of potential assaults.
- Enforce the principle of least privilege by allowing users only the access rights required for their responsibilities.
- With a dedicated security team of Binary IT, monitor your network round-the-clock for potential threats, ensuring rapid response to any incidents that arise.
The Australian Government has also developed a Strategy to position itself as a global leader in cybersecurity by 2030. The Strategy aims to protect Australians by enhancing cybersecurity, managing cyber risks, and supporting citizens and businesses in navigating the cyber landscape. The Strategy envisions a future where robust cyber protections enable prosperity and quick recovery from cyber attacks.
How Binary IT helps to protect against fileless malware attacks
We understand the criticality of protecting your business against fileless malware attacks. That’s why we leverage our expertise in Sydney, your trusted partner in cybersecurity.
By implementing advanced threat detection mechanisms that analyse behaviour, detect anomalies, and identify memory-based attacks, we ensure that fileless malware is swiftly detected and mitigated. Our Managed security services provide constant monitoring, intrusion detection, and the ability to uncover even the most subtle fileless malware activities. With us by your side, you can rest assured that your organisation is equipped to combat the ever-evolving threats of fileless malware.
Fileless malware is on the rise, but you can fight back. Get in Touch today.