For years, security experts have warned about the inherent vulnerabilities in a crucial technology at the heart of global communications. This technology, known as Signalling System 7 (SS7), has been identified as dangerously insecure, and recent revelations have confirmed its use in various espionage activities, particularly in the United States.
Kevin Briggs, an official at America’s Cybersecurity and Infrastructure Security Agency (CISA), recently informed the Federal Communications Commission (FCC) about numerous incidents involving unauthorized attempts to exploit SS7. These exploits have resulted in the theft of location data, monitoring of voice and text messages, delivery of spyware, and even attempts to influence American voters through text messages. This information, initially reported by 404 Media, highlights the growing concerns around telecommunications security.
SS7, developed in the 1970s, was initially designed to enable telecom firms to exchange data necessary for setting up and managing calls. It was a simpler time when security was less of a concern because access to the system was limited to a few fixed-line operators. However, the advent of the mobile age drastically changed this landscape. SS7 and its newer counterpart, Diameter, became essential for various tasks, including international roaming. According to the US Department of Homeland Security, SS7 is particularly vulnerable due to the tens of thousands of entry points worldwide, many of which are controlled by states with malicious intent.
The vulnerabilities of SS7 have been known for over 15 years. In 2008, security researcher Tobias Engel demonstrated that SS7 could be used to pinpoint a user’s location. This was expanded upon in 2014 by German researchers who showed that SS7 could also be exploited to intercept calls and messages. Attackers could reroute data to themselves or, if in proximity to the targeted phone, intercept and decrypt communications. Intelligence agencies have long been aware of these vulnerabilities and have been exploiting them.
A notable instance of SS7 exploitation occurred in April 2014, when Russian hackers used it to spy on Ukrainian political figures. In 2017, a German telecom company admitted that attackers had intercepted SMS authentication codes from banks to steal money from customers. In 2018, an Israeli private intelligence firm leveraged a mobile operator in the Channel Islands to access SS7, which was used to track an Emirati princess abducted by the UAE. Cathal McDaid of Enea, a Swedish telecom and cybersecurity firm, reported that Russian hackers had been using SS7 to monitor dissidents abroad for years.
In 2014, Chinese hackers exploited SS7 to steal vast amounts of data from the Office of Personnel Management, which manages America’s federal civil service. Among the stolen data were security-clearance records containing highly personal details and phone numbers. The US Department of Homeland Security observed “SS7 anomalous traffic” during the breach, linking it to the attack.
Briggs’s comments to the FCC underscore the widespread and ongoing nature of SS7-related exploits. He indicated that the reported incidents are merely the “tip of the iceberg,” highlighting the persistent insecurity of mobile networks. While mobile-network operators can implement measures to block some attacks, many have not taken adequate precautions.
To protect against SS7-based eavesdropping, phone users can use end-to-end encrypted messaging apps such as WhatsApp, Signal, or iMessage. However, these apps are not immune to spyware that can take over devices and capture keystrokes and screen content. In April, Apple alerted users in 92 countries about a “mercenary spyware attack.” Amnesty International’s report in May revealed how a network of surveillance suppliers, brokers, and resellers from countries like Israel, Greece, Singapore, and Malaysia facilitated the deployment of sophisticated spyware by state agencies in Indonesia.
The inherent insecurity of SS7 calls for innovative solutions, and blockchain technology offers promising avenues to enhance telecommunications security. Blockchain’s decentralized and immutable nature can be leveraged to create more secure communication protocols, reducing the risk of unauthorized access and data breaches. By integrating blockchain with existing telecom infrastructure, it is possible to develop a robust and transparent system that ensures the integrity and security of communications.
In conclusion, the persistent vulnerabilities of SS7 and the newer Diameter protocol highlight the need for urgent action to secure global telecommunications. Blockchain technology presents a viable solution to address these security challenges, offering a way to protect against espionage and unauthorized data access. As the digital landscape continues to evolve, adopting blockchain-based security measures could be crucial in safeguarding the future of global communications.
