User authentication based on SS7 call forwarding detection

A computer-implemented method for granting a user access to a network-accessible service, the method comprising:

• maintaining data reflecting call forwarding configurations, wherein each call forwarding configuration comprises a call forwarding type and a call forwarding number, the call forwarding number characterizing a number to which a call is forwarded;
• receiving a request from a user to access a network-accessible service;
• identifying a mobile telephone number associated with the request;
• obtaining a subscriber identifier associated with the mobile telephone number;
• transmitting, to a telecommunication network, a query of supplementary services associated with the subscriber identifier;
• receiving, from the telecommunication network, a query response that comprises information of supplementary services associated with the subscriber identifier, the supplementary services information comprising forwarding information associated with the subscriber identifier;
• evaluating the received supplementary services information to detect conditions indicative of fraud, wherein the evaluation is based on comparing the forwarding information associated with the subscriber identifier to the call forwarding numbers of the maintained call forwarding configurations;
• generating, based on whether a condition indicative of fraud is detected, an authentication request;
• receiving an authentication response from the user in response to the authentication request;
• and
• granting or denying the user access to the network-accessible service based on the authentication response.