OAuth Account Takeover vulnerability arises when there are misconfigurations or flaws in the OAuth 2.0 protocol, a standard used for access delegation commonly used for token-based user authentication. Real-world incidents of OAuth Account Takeover have been reported, showcasing the risks associated with this vulnerability:

### Real-world Cases:

- **Microsoft OAuth Phishing Attack**: Attackers used malicious OAuth apps to steal customer emails, later utilizing these accounts to launch phishing attacks targeting corporate users.
- **GitHub and Travis CI**: Attackers stole OAuth tokens to breach GitHub accounts, using Travis CI and Heroku as backdoors.
- **WayDev**: OAuth tokens were stolen from WayDev to execute a supply chain breach.

### Business Impact:

- Researchers discovered that around 41.21% of mobile applications using OAuth 2.0 were vulnerable, potentially putting over a billion users at risk. The affected applications span a variety of domains including travel planning, hotel booking, chatting, dating, finances, downloading, shopping, and browsing, indicating a wide business impact.
- Misuse or misconfiguration of OAuth 2.0 can have a tremendous impact by allowing over-privileged third-party applications or eventual account takeover by malicious attackers.
- In a case involving Booking.com, OAuth misconfigurations could have led to large-scale account takeover (ATO) on customers' accounts and server compromise, which would have enabled bad actors to manipulate platform users.
- Businesses may have to implement additional logic to detect and prevent automated attacks associated with OAuth vulnerabilities, such as continuous small funds transfers, which could require substantial resources to mitigate.

These incidents highlight the importance of proper configuration and management of OAuth implementations to mitigate the risks of account takeover, which could have severe repercussions