A South Korean telecom company, KT Corporation, has been found to have infected over 600,000 users with malware in an attempt to stop them from using a file-sharing service. The malware was planted on customers' computers without their consent, causing missing files, strange folders, and disabled PCs. The company claimed it had no choice but to control the file-sharing service, which it deemed malicious. The incident has led to investigations and potential charges against KT employees and subcontractors.