Ukrainian hacker pleads guilty to Nefilim Ransomware attacks in U.S.

A Ukrainian national, Artem Aleksandrovych Stryzhak, aged 35, pleaded guilty in the United States to conspiracy to commit computer fraud in connection with Nefilim ransomware attacks. He was arrested in Spain in 2024 and extradited to the United States in April 2025, with sentencing set for May 2026, after facing up to 10 years’ imprisonment.

The DoJ’s press release notes that his co-conspirator, Volodymyr Tymoshchuk, remains at large and is the subject of an $11 million reward offered by the United States Department of State. Nefilim ransomware was used to encrypt networks worldwide, targeting high-revenue companies in the United States, Canada, or Australia, with more than $100 million in annual revenue, and attackers claimed to post stolen data on public “Corporate Leaks” sites if victims did not comply.

The case underscores efforts to hold individuals accountable for ransomware extortion, with federal prosecutors stating that Stryzhak’s conviction demonstrates the Office’s determination to pursue cyber criminals. According to DoJ’s press release, Stryzhak admitted his role in a series of international ransomware attacks.