In this article, you'll find detailed information about the nature of a sinkhole attack, how it's executed, and practical security tips to help you protect your computer and data from potential threats.
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The article discusses a cyberattack technique called “Living off the Land” (LOTL), which involves attackers using legitimate tools and functions already present on a victim’s system to perform malicious actions without the need to install additional malware. This approach makes attacks difficult to detect because attackers use standard system utilities such as PowerShell or Windows Management Instrumentation (WMI), allowing them to remain undetected by traditional defenses.
Living off the land (LOTL) is a fileless malware or LOLbins cyberattack method where a cybercriminal uses native legitimate tools on a victim’s system to support and advance the attack.
Unlike traditional malware attacks that rely on signature files to achieve their goals, LOTL attacks do not require the victim to download or deploy third-party code. Instead, the attacker uses tools already present in the operating system, such as PowerShell, Windows Management Instrumentation (WMI), or the Mimikatz password-reading utility, to achieve their goals.
Since the attack process uses legitimate system resources, it is much more difficult to detect them, especially if the organization’s cybersecurity is based on traditional solutions that focus on searching for known malicious files or scripts. This allows attackers to remain unnoticed in the company’s internal environment for a long time—from several weeks to months or even years.
If attackers using LOTL do not need to install third-party code to launch a fileless attack, how do they infiltrate a system and modify its standard tools for their own purposes? Access to the environment can be gained in a variety of ways, including:
Exploiting vulnerabilities in software that allow unauthorized access to a system.
Stealing credentials through phishing attacks or using keyloggers.
Exploiting remote access, such as through misconfigured RDP, SSH, or VPN connections.
Using legitimate system utilities such as PowerShell, Windows Management Instrumentation (WMI), or Mimikatz to collect data and execute commands without downloading malicious files.
Compromising third-party vendors or partner networks that have access to a company’s internal infrastructure.
Using social engineering techniques, such as tricking a user into granting access or running a command.
Exploits are a set of code, a sequence of commands, or specific data designed to exploit known vulnerabilities in software or an operating system. Exploit kits are collections of such tools that allow attackers to automate attacks.
Exploits are an effective way to launch fileless attacks such as LOTL because they can be executed directly in memory, leaving no trace on disk. This allows attackers to scale the initial stages of compromising a system.
Whether the attack uses traditional malware or is fileless, the exploit always starts the same way. Typically, the victim is tricked into interacting with malicious content via a phishing email or social engineering techniques. Exploit kits typically include a set of tools for various vulnerabilities and a management console that allows the attacker to gain control of the system. Some of them can also scan the target system for vulnerabilities and create a corresponding exploit in real time, adapting to the specific situation.
In LOTL attacks, attackers typically hijack legitimate tools to elevate privileges, gain access to various systems and networks, steal or encrypt data, install malware, install backdoors, or otherwise advance the attack path. Examples of proprietary or dual-use tools include:
File Transfer Protocol (FTP) clients or system functions such as PsExec
Forensic tools such as the Mimikatz password extractor
PowerShell, a scripting platform that offers extensive functionality for administering Windows devices
WMI, an interface for accessing various Windows components
Registry-resident malware is malicious code that is injected directly into the Windows registry, allowing it to remain active and resistant to detection by traditional security tools.
Typically, Windows infections are caused by a bootloader program that receives a malicious file and keeps it active on the system. This makes it potentially vulnerable to antivirus scanning. Fileless malware, on the other hand, works differently: instead of downloading a separate malicious file, a dropper program writes malicious code directly into the Windows registry.
This code can be programmed to run automatically every time the operating system boots, remaining hidden in system files that are not usually scanned by antiviruses.
One of the first examples of this type of attack was Poweliks, followed by other variants such as Kovter and GootKit. Malware that makes changes to registry keys often remains undetected for a long time, which allows attackers to use it for long-term attacks.
Malware designed to run solely in memory leaves no traces on the disk, making it difficult to detect with traditional security methods. One of the most prominent examples of such software is the Duqu worm, which remains undetected because it is stored entirely in RAM.
Its advanced version, Duqu 2.0, has two variations. The first is a backdoor that allows attackers to gain initial access to the system and establish themselves in the victim’s network. The second is an extended version that provides reconnaissance, lateral movement between nodes, and data theft.
Duqu 2.0 has been used in successful attacks on companies in the telecommunications sector, as well as on one of the leading cybersecurity software vendors, demonstrating its high level of sophistication and effectiveness.
Attackers are not limited to one attack method, but use any technology that helps them inject malicious code into a target system. Modern cybercriminals actively use fileless techniques, which allow them to inject malicious code directly into documents using embedded scripting languages such as macros, or load it into memory via exploits.
Ransomware also uses these methods, hijacking legitimate system utilities such as PowerShell to encrypt the victim’s files without leaving any traces on the disk. This makes such attacks extremely difficult to detect by traditional antivirus tools, since the malicious code does not exist as a separate file, but runs exclusively in the memory of the infected system.
Attackers can launch a fileless attack by using stolen credentials to gain access to their target while impersonating a legitimate user. Once inside, the attacker can use their own tools, such as WMI or PowerShell, to carry out their attack. They can establish persistence by hiding code in the registry or kernel, or by creating user accounts that give them access to any system they choose.
Data from CrowdStrike’s 2023 Global Threat Report shows a significant increase in attacks that do not involve traditional malware. In particular, in the last quarter of 2021, 62% of detected threats used legitimate credentials and built-in system tools instead of traditional malware. This is a characteristic of Living off the Land (LOTL) attacks, where attackers exploit existing system resources to achieve their goals.
These attacks are gaining popularity because they are significantly more effective than classic methods using viruses and trojans. They are harder to detect with outdated cybersecurity tools, which gives attackers more time to escalate privileges, steal sensitive data, and install backdoors for further unauthorized access. This makes such attacks especially dangerous for corporate and government networks that do not have modern behavioral threat analysis tools.
Other reasons why LOTL attacks are attractive to cybercriminals:
Many common LOTL attack tools, such as WMI and PowerShell, are on the “allowed” list of the victim’s network, providing the perfect cover for attackers to carry out malicious activity—activity that is often overlooked by the victim’s security operations center (SOC) and other security measures.
LOTL attacks do not use files or signatures, meaning that attacks cannot be compared or linked, making it difficult to prevent in the future and allowing criminals to reuse the tactic at will.
The use of legitimate tools and the lack of a signature make it difficult to attribute LOTL attacks, thus reinforcing the attack cycle.
The long latency period allows an adversary to create and execute sophisticated, complex attacks. By the time the victim is aware of the problem, there is often little time to respond effectively.
Fileless ransomware and LOTL attacks are notoriously difficult to detect using signature-based methods, outdated AV, whitelists, sandboxing, or even machine learning-based analysis. So how can organizations protect themselves from this common and potentially devastating type of attack?
Here, we share a short list of security measures that, when taken together as an integrated approach, can help prevent and detect LOTL, fileless malware, unknown ransomware, and similar attack methods:
One of the most effective approaches to mitigate the risk of Living off the Land (LOTL) attacks is to use Indicators of Attack (IOA) instead of traditional Indicators of Compromise (IOC).
Unlike IOCs, which capture traces of attacks that have already been carried out, IOAs are a proactive detection method. They analyze suspicious activities that may indicate the deployment of an attack, including code execution, movement on the network (lateral movements), and attempts to hide the attacker’s activity.
IOAs are particularly effective against fileless attacks because they do not focus on how the malicious code is executed – it is not important where the attack originated (from the hard drive or fileless equipment), but what exactly is happening in the system. By analyzing the sequence of events, the relationships between actions, and the context, this method allows you to detect even sophisticated attacks that are disguised as legitimate processes.
Fileless attacks often use legitimate system tools, such as PowerShell, and never leave files on the disk. This allows them to bypass signature methods, whitelists, and sandboxes. Even machine learning-based solutions may not be able to detect such attacks. However, IOA analyzes behavioral patterns and reveals the attacker’s true intentions.
Because this method takes into account context, sequence of actions, and intent, it can detect threats even if they are carried out through legitimate accounts or compromised applications. This is especially important when the attacker is using stolen credentials, a common tactic in LOTL attacks.
Threat hunting in the context of fileless attacks is a complex and resource-intensive process that requires the collection, analysis, and normalization of large amounts of data. However, without this component, effective protection against fileless malware is practically impossible. That is why for most organizations, the best solution is to outsource this function to specialized expert vendors.
Managed threat hunting services operate 24/7, actively monitoring suspicious activity, analyzing threats, and detecting intrusions that might otherwise go unnoticed by traditional cybersecurity tools. They help organizations prevent attacks at an early stage, before they escalate into large-scale data compromises.
Threat hunting has become a key element of modern cybersecurity, as it allows you to detect hidden attacks by analyzing subtle behavioral patterns of attackers. By using managed threat detection, companies gain access to a team of professional experts who continuously analyze security data, identifying the subtle signs of sophisticated attacks.
Such managed threat detection services are designed specifically to fill critical gaps in defense systems, providing organizations of all sizes with reliable proactive security.
Account monitoring and management controls can detect and prevent unauthorized activity by providing complete visibility into your work environment. This helps prevent data loss due to account breaches and credential breaches, while also allowing resource owners to control who has access to data and indicate whether access has been granted improperly.
Early detection of outdated or unpatched applications and operating systems allows you to effectively manage all applications in your environment and increase security. Optimizing your software inventory with modern IT hygiene solutions helps you eliminate potential threats while reducing costs.
Providing visibility into active software through IT hygiene helps prevent attacks that exploit vulnerabilities in legacy systems, and optimize software configuration for improved performance and security.
Real-time application usage tracking and historical analysis help identify unused or underperforming applications that can be safely removed. This not only reduces system load, but also helps organizations save significant amounts of money by reducing unnecessary licensing and support costs for unnecessary software.
Asset Inventory provides a complete view of the devices running on your network, allowing you to effectively implement your security architecture and ensure that your infrastructure is free from unauthorized or rogue systems.
With this tool, security and IT operations teams can clearly distinguish between managed, unmanaged, and unknown assets in the environment, allowing them to take appropriate measures to address vulnerabilities and improve the overall level of cybersecurity. Control over all devices on the network helps minimize the risk of attacks, prevent the use of unprotected resources, and ensure the stability and security of the IT infrastructure.
Attackers using LOTL attacks can remain invisible on a victim’s network for weeks, months, and sometimes years, making recovery from an incident much more difficult. Organizations that suspect a compromise should contact a reputable cybersecurity professional to conduct a Compromise Assessment (CA). This assessment will help determine whether a breach has occurred and what stage of the attack the attacker may be in.
During a compromise assessment, experts analyze historical and current events, looking for signs of suspicious activity, including unknown registry keys, unusual source files, and active threats. Because sophisticated attackers can remain undetected for long periods of time, a thorough analysis of historical logs and network activity is an important part of the assessment.
If a compromise is confirmed, the security team will work to isolate the damage, restore affected systems, and strengthen defenses to prevent further attacks.
To minimize future risks, cybersecurity experts conduct a detailed audit of the network environment to ensure that attackers have not left backdoors or hidden access points. Organizations are also advised to implement modern solutions to protect against fileless attacks, including behavioral threat analysis, anomaly detection tools, and advanced security monitoring tools.
To protect against Living off the Land (LOTL) and fileless threats, a comprehensive approach to cybersecurity is necessary. First, it is important to restrict the use of built-in system tools such as PowerShell, WMI, and PSExec by configuring access policies and script execution controls. Second, you should implement behavioral threat analysis to detect suspicious network activity, even if it is performed by legitimate processes.
In addition, careful credential management will help prevent attacks from stolen or compromised accounts, using multi-factor authentication (MFA), login monitoring, and privilege restrictions. Regular software updates are important, as many LOTL attacks exploit unpatched vulnerabilities. Finally, proactive threat hunting and network activity monitoring will help detect hidden attacks before they cause damage.
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