In today’s digital landscape, the security of mobile communication networks has become a topic of significant concern. A method gaining attention is the ability to impersonate a subscriber in ways similar to a SIM swap, using interconnection flaws within the SS7 Server infrastructure.
Mobile subscribers worldwide rely on network protocols for their daily communication needs. Among these protocols, Signaling System No. 7 (SS7) plays a crucial role, but its vulnerabilities can have far-reaching effects.
Understanding SS7 and Its Significance
SS7, or Signaling System No. 7, was developed in the 1970s to manage connections between telecommunications networks. It enables functions like SMS routing, call setup, real-time billing, and seamless roaming across countries. Mobile operators depend on SS7 to communicate securely and efficiently. However, this protocol was designed in an era when telecom networks were isolated and trusted, lacking the need for modern-day authentication measures.
As mobile usage exploded and networks interconnected globally, the initial trust-based architecture began to reveal its limitations. Today, SS7 is used not just for voice and text, but for many core authentication services. This makes it a target for those interested in accessing network-level capabilities to impersonate subscribers or perform actions similar to SIM swap attacks.
Impersonation Techniques Using SS7
The concept of SIM swapping typically involves an attacker socially engineering a mobile provider to assign a target’s number to a new SIM card. Through SS7 protocol manipulation, it is possible to achieve a similar result without physical access to the victim’s SIM or the need for insider help.
When a threat actor gains access to the SS7 Server, they can request subscriber information, intercept messages, or reroute calls to a device of their choice. By exploiting flaws in SS7, an operator can be tricked into believing that the attacker’s device is, in fact, the genuine subscriber. This opens up avenues for intercepting critical two-factor authentication codes or listening in on personal conversations.
The process generally involves sending network commands such as “Update Location” or “Insert Subscriber Data.” These commands can direct the network to treat the attacker’s device as the legitimate SIM, forwarding calls and texts meant for the victim. Unlike traditional SIM swap techniques, which rely on social engineering, this approach exploits the inherent trust between telecommunications networks themselves.
Risks and Consequences of SS7-Based Impersonation
The implications of impersonating a subscriber via SS7 extend beyond personal inconvenience. When attackers hijack a number, they are often able to access banking information, private emails, and social media accounts associated with that number. Many financial services and verification mechanisms depend on SMS-based one-time passwords to authorize transactions and logins.
Once control over a mobile number is obtained, attackers can request password resets or authentication codes, potentially bypassing account protections. Since these attacks take place silently at the protocol level, victims may not notice anything amiss until unauthorized activity is detected, often after sensitive data or funds have been compromised. Since SS7 vulnerabilities affect networks at an international level, attackers can perform these impersonations from afar, regardless of the victim’s location.
Telecommunications companies and enterprises relying on one-time passcodes sent to mobile devices are increasingly at risk from these protocol-level attacks. Organizations must recognize the potential weaknesses in legacy systems and consider alternative methods for securing user accounts and communications.
Growing Awareness and Industry Response
Recent years have witnessed growing attention toward securing SS7, both from industry bodies and security researchers. Mobile operators are beginning to roll out monitoring and filtering mechanisms to detect suspicious SS7 activity and block unauthorized commands.
Yet, retrofitting robust authentication and encryption measures onto the existing framework remains a challenge, due to the deeply embedded nature of SS7 in telecom infrastructure. Cross-operator cooperation and standardization efforts are progressing, but the global scale of interconnectivity means patching every corner of the network is a massive undertaking.
Conclusion
Impersonating a subscriber through protocol-level manipulation poses challenges not only for individuals but for the entire telecommunications ecosystem. With attackers exploiting legacy weaknesses in systems like SS7, stakeholders must remain vigilant and stay informed about how these attacks operate.
As more services move to mobile-first verification and authentication, organizations and users alike need to recognize the risks involved. By understanding how SS7 operates and where it can be exploited, the industry can work toward a safer and more resilient communication environment.