Companies and individuals in Japan are finding their computers are increasingly targeted by ransomware campaign Attack.Ransom that bar victims from accessing important files unless they pay money Attack.Ransom . “ Attacks on Japanese businesses have been particularly large in number , ” said Masakatsu Morii , a professor of information and telecommunications engineering at Kobe University ’ s Graduate School of Engineering . Ransomware typically infects computers when its user opens a file attached to spam mail from a sender pretending to be Attack.Phishing a legitimate entity such as a parcel delivery company , according to the government-affiliated Information-Technology Promotion Agency . The malicious programs encrypt the infected computers ’ files , and users can only open them after paying Attack.Ransom the perpetrators money to obtain a special key to unlock them . Yoshihito Kurotani , a researcher at the agency ’ s engineering department , said the programs employ basic encryption technologies . Kurotani ’ s agency has received numerous inquiries asking for help from victims who can not access their photos or business files . The bogus emails “ used to be written in English or unnatural Japanese , but we have seen increasing attacks using natural Japanese recently , ” Kurotani said . Computer security firm Trend Micro Inc. said it received 2,810 reports of ransomware attacks Attack.Ransom nationwide in 2016 — a 3.5-fold jump from the previous year . “ Tactics are expected to be even more sophisticated in 2017 , ” a Trend Micro official said . A survey conducted by the firm last June shows that about 60 percent of companies that were attacked Attack.Ransom paid ransoms Attack.Ransom . The payment in one case exceeded ¥10 million ( $ 88,000 ) . The extortion Attack.Ransom and the transactions in the ransomware programs themselves have become a profitable business for cybercriminals . The programs are traded on online black markets that can not be accessed without the use of special software . In the “ dark web ” networks , various programs are sold , including multilingual ones and one that can be used for a “ lifetime ” for just $ 39 . The people who post the programs make profits by taking a share of ransoms collected Attack.Ransom . Firms undertaking the delivery of unsolicited emails do business there , too . Katsuyuki Okamoto , a security “ evangelist ” at Trend Micro , said it has become easier and easier to be involved in or become a victim of cybercrime . Cybersecurity experts warn that users should protect their computers by always keeping operating systems and anti-malware software up-to-date and should constantly back up their data . They said victims should never pay ransoms Attack.Ransom as there is no guarantee their files will actually be restored . “ If you pay money Attack.Ransom to the criminals , that will only help them create a new virus , ” Okamoto said .