WhatsApp API flaw let researchers scrape 3.5 billion accounts
Researchers compiled a list of 3.5 billion WhatsApp mobile phone numbers and associated personal information by abusing a contact-discovery API that lacked rate limiting. [...]
API security focuses on protecting application interfaces from unauthorized access, data exposure, abuse, and flaws in authentication or design.
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Background for this topic.
Application Programming Interfaces (APIs) are sets of rules that allow software applications to communicate and exchange data, often enabling functionality across different systems or services. APIs define how requests and responses are structured, making it possible for programs to interact without direct user involvement. In cybersecurity, APIs are commonly exposed over networks as endpoints that handle sensitive operations like data retrieval, user authentication, or transaction processing.
APIs increase the attack surface by exposing endpoints that attackers can target with unauthorized access attempts, injection attacks, or denial-of-service. Common risks include weak or missing authentication, insufficient input validation, and improper rate limiting. Effective API security requires strong authentication protocols (e.g., OAuth), strict input validation to prevent injection, rate limiting to mitigate abuse, and comprehensive logging to detect anomalies. Protecting APIs is critical to prevent data leaks, privilege escalation, and service disruption in interconnected environments.
Researchers compiled a list of 3.5 billion WhatsApp mobile phone numbers and associated personal information by abusing a contact-discovery API that lacked rate limiting. [...]
Researchers Were Able to Query 3.5 Billion AccountsSecurity researchers were able to scoop up the telephone numbers of billions of WhatsApp users through an enumeration tool provided by app owner Meta. The sheer quantity of leaked numbers - 3.5 billion in total - would amount to "the largest data leak in history."
A multi-layered security framework protecting large-model applications from adversarial threats, data leakage, API abuse, and content risks Partner Content At MWC Shanghai 2025, ZTE has officially launched its ZXCSec MAF product, a dedicated application-layer security protection device specifically designed for large model services.…