How does SIM Cloning take place?
In a SIM cloning attack, the fraudster gains access to the victim's physical SIM card and uses a smart card copying software to create a duplicate of the original SIM. In the process, they get access to the IMSI (International Mobile Subscriber Identity) number of the SIM card. They may also resort to remote hacking, by breaking the encryption of updates sent to the SIM via SMS using over-the-air (OTA) communication.
About IMSI Number of the SIM
Every mobile SIM card issued by Telecom Company has an IMSI (International Mobile Subscriber Identity) number. This IMSI number is a 15-digit code that is linked to that specific SIM, identifying and authenticating the individual subscriber owning the SIM card. It indicates the subscriber's country, and mobile network among other details to identify a mobile phone.