Suspected Russian hacker extradited to US, faces cybercrime charges

A suspected Russian hacker is in U.S. custody after being extradited from Thailand and faces charges related to a cyber espionage campaign. Denis Obrezko, 36, appeared in federal court in Boston, accused of conspiring to commit unauthorized access to a protected computer.

U.S. authorities allege Obrezko facilitated cyberattacks carried out by a Russia-aligned group known as Void Blizzard. The Justice Department's National Security Division is prosecuting the case. Neither the Justice Department nor a court-appointed lawyer for Obrezko responded to requests for comment.

Thailand's Foreign Affairs Ministry stated that Obrezko's extradition complied with Thai law and treaty obligations, while respecting his due process rights. The ministry confirmed the decision was made in accordance with the law and treaty obligations.

Void Blizzard was identified by Microsoft in May 2025 as a new group conducting cyber espionage against organizations relevant to Russian government objectives. The group has targeted entities in NATO member states and Ukraine since April 2024, spanning government, defense, transportation, media, and healthcare sectors.

The FBI affidavit indicates Void Blizzard's activities primarily involved mass email harvesting targeting U.S. companies. At least 11 U.S. companies have been identified as victims, though the actual number is believed to be higher. The FBI linked Obrezko to cryptocurrency transactions used to purchase a virtual private server and domain name for conducting attacks.

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the Thai government's decision to extradite Obrezko was in accordance with Thailand's domestic law and its obligations under the related treaties on extradition, "while fully respecting the due process of law of the defendant."