According to Chugunov, this is because messengers do not have special anti-spam filters and other mechanisms that protect against scammers. Attackers usually sign their accounts on behalf of the Investigative Committee, the mobile operator’s support service, the bank’s security service. With this they further mislead naive people, and also to “help” call forwarding and gain access to receiving SMS codes from the Internet bank.
It is noted that scammers save numbers for making calls on virtual SIM cards of Russian and foreign operators. And recently, VTB customers are increasingly receiving calls from foreign numbers.
Source: Ferra
