Original Post: Bots and Pumping — Effective Guardrails against SMS pumping. | by Goutham Madhwaraj | Sep, 2024
The article discusses the challenges of managing unauthenticated SMS One-Time Password (OTP) verification flows and defending against SMS pumping fraud. SMS pumping involves threat actors working with telecom providers to profit from increased SMS traffic, exploiting vulnerabilities in SMS systems. This issue largely affects companies that rely on third-party SMS services, which are susceptible to being targeted due to cost discrepancies in SMS services across different regions.
The post emphasizes the need for robust anti-bot guardrails as part of a defense-in-depth strategy. It suggests implementing mechanisms like rate limiting and using API gateways with unique consumer IDs to manage and secure SMS traffic. The article also stresses the importance of continuous monitoring for cost spikes and abnormal SMS activity to prevent significant financial losses.
Furthermore, it highlights the role of Web Application Firewalls (WAF) with integrated bot management and fingerprinting rules, such as Cloudflare’s bot management solutions and Turnstile, Twilio’s Native SMS Fraud Guard, and various CAPTCHA solutions like Google reCAPTCHA V3. The choice of CAPTCHA solutions should balance security needs with user experience considerations.
Overall, the post advocates for a combination of proactive measures and advanced tools to safeguard against SMS pumping attacks and effectively manage SMS-based verification systems.
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