International authorities have dismantled AVCheck, a platform used by cybercriminals to test malware against antivirus software. The website avcheck.net now displays a seizure notice from the US Department of Justice, FBI, US Secret Service, and Dutch police. AVCheck was one of the largest counter antivirus services globally, aiding cybercriminals in evaluating their malware's stealth capabilities. Investigators found links between AVCheck's administrators and crypting services like Cryptor.biz and Crypt.guru. Law enforcement had placed a fake login page on AVCheck to warn users about legal risks before its shutdown on May 27, 2025. Undercover agents confirmed the illegal nature of AVCheck through transactions and connections to ransomware attacks. The FBI has also warned about the Silent Ransom Group, which has targeted law firms in the US using social engineering tactics.