Description

Hackers are exploiting fake CAPTCHA pages to trick users into sending large volumes of international SMS messages, turning routine “prove you’re human” checks into a profitable fraud scheme. Victims are redirected through malicious or typosquatted domains via traffic distribution systems (TDS) to fake CAPTCHA pages. Instead of solving a challenge, users are repeatedly asked to “confirm” verification, with each step opening their SMS app pre-filled with international numbers. In some cases, a single session can trigger up to 60 SMS messages to high-cost destinations, leading to unexpected charges that often go unnoticed until later. The campaign relies on International Revenue Share Fraud (IRSF), where attackers earn money by sending SMS traffic to premium-rate numbers in high-fee regions. Telecom operators pay termination fees to foreign carriers, who share revenue with the fraudsters. The scheme is scaled using TDS infrastructure, affiliate tracking, and techniques like back button hijacking to trap users in repeated SMS loops. Tracking mechanisms using cookies and parameters help target users based on location, device, and network, making detection difficult. Organizations should monitor unusual international SMS activity and detect anomalies across telecom networks. Security teams should block malicious domains and implement protections against forced redirects. Users should avoid suspicious CAPTCHA pages and carefully review SMS prompts. Telecom providers should share IRSF indicators and enforce stricter controls on high-risk routing. Regular awareness training and endpoint security can further reduce exposure.