The CrazyHunter hacker group has been targeting critical sectors in Taiwan, including healthcare, education, and industry. Since early 2025, they have been executing sophisticated ransomware attacks using open-source tools available on GitHub. These tools significantly lower the cost of conducting complex attacks, enabling CrazyHunter to carry out operations with a high degree of operational efficiency.
CrazyHunter’s attack approach employs the Bring Your Own Vulnerable Driver (BYOVD) technique to bypass security defenses. By exploiting vulnerable, legitimate drivers already installed on victim systems, they can disable security mechanisms and deploy ransomware with minimal detection. Their operations indicate a level of sophistication often seen in advanced persistent threat (APT) groups, marking a departure from traditional ransomware operations..
Trend Micro researchers discovered that a significant portion of CrazyHunter’s attack tools are sourced from GitHub, modified to enhance their effectiveness.
About 80% of their toolkit consists of publicly available resources, which makes the campaign more accessible for other potential threat actors. The group is specifically targeting Taiwanese organizations, as shown by victim data and email addresses linked to Taiwan-based domains. After infiltrating networks, CrazyHunter employs several tools to disable security mechanisms, maintain access, and encrypt files with a customized ransomware payload.
The attack’s execution is driven by a batch script that orchestrates the deployment of various components in sequence.
This script first disables security products using the vulnerable Zemana Anti-Malware driver before loading the ransomware driver and starting the encryption process. The ransomware, a modified version of the Prince ransomware builder, adds the “.Hunter” extension to encrypted files and leaves ransom demands on victim desktops. By employing redundant measures, CrazyHunter ensures that even if primary methods fail, the ransomware deployment continues through alternative pathways.
