The Mariposa botnet, one of the most notorious malicious networks active on the web in recent years, was taken down on December 23. Spanish police announced on Wednesday, however, that they made three arrests in conjunction with the case. Spanish police, along with two computer security firms, Defense Intelligence and Panda Security, located the men responsible for spreading the malware. The tracking of the men began in May of 2009, but it took nearly nine months to shut down the malware strain. Latest estimates saidthat the virus spread to 190 countries and more than 11 million unique IP addresses. “Our preliminary analysis indicates that the botmasters did not have advanced hacking skills,” Pedro Bustamante, senior research advisor at Panda Security, wrote in a March 3 statement. “This is very alarming because it proves how sophisticated and effective malware distribution software has become, empowering relatively unskilled cyber-criminals to inflict major damage and financial loss.” In recent weeks, web and software security firms reported the discovery of the Kneber botnet, which infected nearly 75,000 computers worldwide. Also, Microsoft successfully destroyed the Waldedac botnet after receiving a court order to shut down domains known to infect computers with it.