The US Department of Justice and FBI said today they had filed a civil complaint, executed criminal warrants, and a temporary restraining order as part of what they called the most comprehensive enforcement action ever taken by US authorities to disable an international botnet.The target of this massive effort is Coreflood, which the DOJ labels a particularly harmful type of malicious software that records keystrokes and private communications mostly on Windows computers. \u00a0More on FBI cases: FBI wants public help solving encrypted notes from murder mysteryCoreflood allows infected computers to be controlled remotely for the purpose of stealing private personal and financial information from unsuspecting computer users, including users on corporate computer networks, and using that information to steal funds, the FBI said. According to information contained in court filings, the group of all computers infected with Coreflood is known as the Coreflood botnet, which is believed to have been operating for nearly a decade and to have infected more than two million computers worldwide.The DOJ said the botnet\u2019s operators would send out new versions of the malware are on a regular basis, in an effort to stay ahead of security software and other virus updates. \u00a0If the servers didn\u2019t respond, the existing Coreflood malware continued to run on the victim\u2019s computer, collecting personal and financial information.From the FBI: The U.S. Attorney\u2019s Office for the District of Connecticut has filed a civil complaint against 13 \u201cJohn Doe\u201d defendants, alleging that the defendants engaged in wire fraud, bank fraud and illegal interception of electronic communications. \u00a0In addition, search warrants were obtained for computer servers throughout the country , and a seizure warrant was obtained in U.S. District Court for the District of Connecticut for 29 domain names. \u00a0Finally, the government obtained a temporary restraining order, authorizing the government to respond to signals sent from infected computers in the United States in order to stop the Coreflood software from running, thereby preventing further harm to hundreds of thousands of unsuspecting users of infected computers in the United States.The FBI and DOJ said they have replaced the illegal Coreflood servers with substitute servers to prevent Coreflood from causing further injury to the owners and users of infected computers and other third parties. \u201cBy limiting the defendants ability to control the botnet, computer security providers will be given time to update their virus signatures and malicious software removal tools so that all victims can have a reliable tool available to them that removes the latest version of the malware from an infected computer,\u201d the FBI said.