The rapidly evolving landscape of cybercrime has given rise to ingenious tactics employed by ransomware groups. The Kasseika ransomware group is the latest to make headlines with their utilization of the Bring Your Own Vulnerable Driver (BYOVD) attack. By leveraging this attack tactic, threat actors are able to disarm security-related processes on compromised Windows hosts, thereby facilitating the deployment of ransomware.
BYOVD Attack: Disarming Security Processes
The BYOVD attack is a sophisticated technique that allows threat actors to terminate antivirus processes and services on compromised Windows hosts. This tactic provides them with the necessary access and control to deploy ransomware. By disabling security measures, the attackers can execute their malicious payload without being detected, leaving victims vulnerable to data encryption and extortion.
Potential links to the BlackMatter ransomware group
Interestingly, Kasseika exhibits several overlaps with the now-defunct BlackMatter ransomware group. This has led to speculation that Kasseika may have acquired or purchased access to BlackMatter’s resources, including their expertise and infrastructure. The similarity in tactics and techniques suggests the involvement of an experienced threat actor behind the Kasseika ransomware.
Attack Chain: Phishing Email and Lateral Movement
The attack chain employed by Kasseika begins with a phishing email as the initial access point. Through social engineering and manipulation techniques, the threat actors trick unsuspecting individuals into clicking on malicious links or opening infected attachments. Once inside the target network, Kasseika moves laterally, exploring different systems and compromising additional endpoints to gain broader control.
Utilization of Microsoft’s Sysinternals PsExec utility
To carry out their malicious activities, Kasseika employs Microsoft’s Sysinternals PsExec command-line utility. This powerful tool allows the threat actors to execute a malicious batch script across the compromised network, helping them rapidly spread their malware and maintain persistence within the compromised systems.
Disabling security tools with “Martini.exe” and “Martini.sys”
A crucial component of Kasseika’s attack is the use of the “Martini.exe” executable. This executable is responsible for downloading and running the “Martini.sys” driver on the compromised system. This driver plays a pivotal role in disabling various security tools and processes, rendering the system vulnerable to ransomware deployment.
Ransomware payload: Encryption process
Once the security processes have been disarmed, Kasseika deploys its ransomware payload, known as “smartscreen_protected.exe.” This malicious file carries out the encryption process using advanced algorithms such as ChaCha20 and RSA. The encryption renders the victim’s files inaccessible, leaving them at the mercy of the attackers.
Ransom Note and Payment Demand
In every directory that has been successfully encrypted, Kasseika leaves a ransom note. This note serves as a chilling reminder of the victim’s predicament and provides instructions on how to make the ransom payment. Additionally, the attackers modify the victim’s computer wallpaper to display a prominent payment demand, further increasing the pressure on the victim to comply.
Evading Detection: Wiping System Event Logs
To operate discreetly and evade detection by security tools, Kasseika takes steps to wipe the system event logs. Using the wevtutil.exe binary, the ransomware obliterates any traces of its activities, making it significantly harder for security analysts and incident responders to identify and mitigate the threat promptly.
The emergence of the Kasseika ransomware group and their utilization of the BYOVD attack tactic highlights the ever-evolving threat landscape faced by individuals and organizations. Threat actors continuously adapt their strategies, making it crucial for security professionals to stay vigilant and implement robust defensive measures. Understanding the tactics employed by groups like Kasseika is essential for effectively mitigating the risks posed by ransomware attacks. It is imperative to enhance employee education, deploy multi-layered security defenses, and regularly update and patch systems to minimize the likelihood of falling victim to these malicious endeavors.