Phishing Story #3: The Duolingo Data Breach of 2023

What Happened?

Duolingo, a widely-used language learning app, suffered a data breach exposing the personal information of 2.6 million users. A threat actor exploited a bug in Duolingo’s API, which allowed them to scrape user data, including names, email addresses, and details about language studies and social network profiles​​.

The Impact

The breach put millions at risk of doxxing and targeted phishing attacks, compromising user privacy and potentially their online security.

Lessons Learned

The incident highlights the critical importance of securing APIs against vulnerabilities that can lead to data scraping and unauthorized access to user information.

Tips for Businesses

1. API Security: Regularly audit and update APIs to patch vulnerabilities and prevent unauthorized data access.

2. User Privacy Protection: Ensure that user data, especially when publicly accessible, is adequately protected against scraping.

3. Rapid Response Plan: Develop a quick response strategy for addressing security breaches and mitigating their impact.

4. Transparency with Users: Communicate openly with users about data breaches, emphasizing measures taken for their protection.

5. Ongoing Monitoring: Continuously monitor systems for unusual activities to detect and prevent potential breaches early.