Many online services rely on SMS codes for registration to deter “fake” accounts. However, a thriving grey market allows users to bypass these security measures for a small fee.

A year-long study by Cambridge University researchers has shed light on the online marketplace, where vendors buy SIM cards in bulk to sell verification services. As of Dec 23, verifying a Malaysian account averaged just US$0.40 (RM1.62).

The actual price varies by...