According to Bloomberg News, the official website of Johannesburg was hacked, and hacker groups demanded payment of ransom in bitcoin. After discovering a network vulnerability that led to unauthorized access to its information system, the city closed its billing system for precautions. A hacker group called "Shadow Kill" posted a message on the city's website asking for four ransem to pay the ransom. The hacker threatened that if they did not pay the ransom, they would upload all hijacked data to the Internet by October 28. Security experts are currently investigating the incident and they have taken immediate action and the investigation will last for 24 hours.