How Union Bank of India retrieved hacked $171 mn in 6 days?

Government-owned Union Bank of India, which lost $171 million (₹1,100 crore at today's rates) because of a hack last year, worked with the RBI and government to track and retrieve the amount within six days. The heist had taken place through a phishing email that appeared to be from the RBI, causing the transfer of funds to four different countries.