Cybercriminals often use unsophisticated methods that continue to be extremely successful. Hackers often use phishing emails to harvest credentials and gain easy access to business-critical environments. As businesses move to a remote workforce, hackers have increased their activity to capitalize on new security holes. Report the hack to your customers and business stakeholders. Engage the help of law enforcement. Immediately contain and isolate critical systems. Immediately isolate known infected clients from the network as soon as possible. Identify the infection or malicious code will spread from isolated clients.
Source: https://thehackernews.com/2021/05/what-to-do-when-your-business-is-hacked.html