Four men from Eastern Europe have pleaded guilty to supporting cyber-criminals attacking the United States by providing them with bulletproof hosting services (BPHS). BPHS are run with a 'don't ask, don't tell' approach and ensure the anonymity of users while allowing them to host malicious activity and content such as malware. According to court documents, 34-year-old Russian nationals Aleksandr Grichishkin and Andrei Skvortsov, 33-year-old Aleksandr Skorodumov of Lithuania, and Estonian 30-year-old Pavel Stassi were the founders and/or members of an organization offering BPHS. The group admitted renting out Internet Protocol (IP) addresses, servers, and domains to cyber-criminal clients, who used them to steal banking credentials, spread malware, and form botnets.