Spoofing Against Spoofing: Towards Caller ID Verification In Heterogeneous Telecommunication Systems

TL;DR

This paper introduces CIV, a PKI-free caller ID verification method that uses challenge-response and leverages spoofing to combat caller ID spoofing across heterogeneous telecommunication systems, including IP and non-IP networks.

Contribution

It presents the first working prototype of a caller ID verification system applicable to VoIP, cellular, and landline phones, supporting heterogeneous networks without relying on PKI.

Findings

CIV effectively authenticates caller IDs across different telecom systems.

Spoofing is used innovatively to implement challenge-response verification.

The system can be integrated into telecom clouds for scalable deployment.

Abstract

Caller ID spoofing is a global industry problem and often acts as a critical enabler for telephone fraud. To address this problem, the Federal Communications Commission (FCC) has mandated telecom providers in the US to implement STIR/SHAKEN, an industry-driven solution based on digital signatures. STIR/SHAKEN relies on a public key infrastructure (PKI) to manage digital certificates, but scaling up this PKI for the global telecom industry is extremely difficult, if not impossible. Furthermore, it only works with IP-based systems (e.g., SIP), leaving the traditional non-IP systems (e.g., SS7) unprotected. So far the alternatives to the STIR/SHAKEN have not been sufficiently studied. In this paper, we propose a PKI-free solution, called Caller ID Verification (CIV). CIV authenticates the caller ID based on a challenge-response process instead of digital signatures, hence requiring no PKI. It supports both IP and non-IP systems. Perhaps counter-intuitively, we show that number spoofing can be leveraged, in conjunction with Dual-Tone Multi-Frequency (DTMF), to efficiently implement the challenge-response process, i.e., using spoofing to fight against spoofing. We implement CIV for VoIP, cellular, and landline phones across heterogeneous networks (SS7/SIP) by only updating the software on the user's phone. This is the first caller ID authentication solution with working prototypes for all three types of telephone systems in the current telecom architecture. Finally, we show how the implementation of CIV can be optimized by integrating it into telecom clouds as a service, which users may subscribe to.