SS7 and Diameter Signaling Protocol Vulnerabilities Enable Global Mobile Interception

Security researchers have long warned about the inherent weaknesses in global telecom signaling protocols. The SS7 (Signaling System No. 7) protocol, which routes voice and text traffic across legacy and modern networks, and the Diameter protocol, which serves as the foundation for 4G and 5G core networks, were designed with trust assumptions that no longer hold in the current threat landscape.

According to the report, attackers can exploit these protocols by sending specially crafted signaling messages. Because SS7 and Diameter rely on the assumption that network nodes are legitimate, malicious actors can perform location tracking, intercept calls and SMS (including one-time passwords and 2FA codes), and even impersonate subscribers. The attack path typically does not require physical access to the target device; instead, it exploits the trust relationship between different carrier networks.

The implications are significant. SMS-based two-factor authentication, widely used for banking, social media, and enterprise access, can be bypassed if an attacker intercepts the verification code via these signaling flaws. Similarly, real-time location tracking undermines the privacy and safety of users.

Cape, a security-focused mobile service provider, discusses these vulnerabilities and promotes its own service as a defensive measure. However, the underlying protocol flaws affect the broader telecommunications industry. Security experts note that there is no single patch for these issues, as they stem from the original design of the protocols. Mitigation involves implementing signaling firewalls, enforcing TLS encryption for Diameter traffic, and deploying network monitoring to detect anomalous signaling patterns. Users are advised to transition away from SMS-based 2FA toward authenticator applications or hardware keys.