TL;DR: Instagram ($2000), Google ($0) and Microsoft ($500) were vulnerable to direct money theft via premium phone number calls. They all offer services to supply users with a token via a computer-voiced phone call, but neglected to properly verify whether supplied phone numbers were legitimate, non-premium numbers. This could have allowed a dedicated attacker to steal thousands of EUR/USD/GBP/… . Microsoft was exceptionally vulnerable to mass exploitation by supporting virtually unlimited concurrent calls to one premium number. The vulnerabilities were submitted to the respective Bug Bounty programs and properly resolved.