Impersonating a mobile subscriber is a technique that has attracted attention due to its similarities with SIM swap attacks. By leveraging the vulnerabilities of the SS7 Server, threat actors have managed to bypass typical security checks and gain unauthorized control over victims’ mobile communications.
The process behind such impersonation does not always require physical access to the target’s SIM card. Instead, it exploits flaws within core telecommunications protocols, providing an avenue for interception and manipulation on a global scale.
Understanding SIM Swap and SS7 Vulnerabilities
SIM swap attacks typically involve someone social engineering a mobile provider to issue a new SIM card for a victim’s phone number. In this way, attackers receive all SMS messages and calls meant for the original user, which can lead to unauthorized access to bank accounts, email accounts, and two-factor authentication-protected services.
However, an attack leveraging the SS7 network infrastructure does not always follow this approach. The SS7 protocol, developed in the 1970s, was designed to interconnect mobile networks for roaming and message delivery purposes. Unlike physical SIM swap fraud, exploiting SS7 allows an attacker to intercept or redirect communications at the network level, making detection far more challenging.
How Attackers Impersonate Subscribers via SS7 Server
Modern mobile networks rely on trusted interaction between network operators through protocols established decades ago. The insufficient security controls of these protocols present an attractive opportunity for those seeking to impersonate subscribers. By gaining access to specialized platforms such as an SS7 Server, an attacker can send crafted signaling messages that manipulate network records about a user’s location and status.
This manipulation can trick the telecommunications network into believing the subscriber has moved to a device controlled by the attacker. As a result, all calls, texts, and sometimes even data intended for the subscriber are routed directly to the attacker’s device. Unlike standard SIM swaps, the victim often keeps operating as usual without realizing there is a parallel session capturing their information in real time.
The Risks and Impacts of Subscriber Impersonation
Subscriber impersonation using SS7 techniques often targets high-value individuals or entities where interception of sensitive SMS or voice traffic can reap significant rewards. Criminal elements can, for instance, intercept one-time passwords used for banking, social network access, or business communications without needing to interact with the telecom provider or the end user directly.
Beyond financial theft or personal account compromise, such attacks can extend to surveillance or unauthorized access across multiple online platforms. Because the SS7 network was not designed with modern security concerns in mind, breaches can occur outside the borders of the victim’s home country, complicating the process of tracing and responding to such attacks.
Conclusion
The evolution of subscriber impersonation from physical SIM swap tactics to exploitation of mobile network infrastructure highlights the importance of robust telecommunications security. With the ability to reroute or intercept communications using the backend of global networks, attackers no longer rely solely on social engineering or local vulnerabilities—they can now act from anywhere in the world.
Heightened awareness among mobile users and proactive measures among network operators remain crucial. As the SS7 protocol persists in underpinning much of the world’s mobile communications, understanding its potential for misuse is key to appreciating the ongoing risks associated with modern, network-based impersonation tactics.