LTE, 5G Vulnerabilities Could Cut Entire Cities From Cellular Connectivity

The widespread adoption of LTE and 5G technologies has revolutionized global communication, enabling faster connectivity, lower latency, and the infrastructure for futuristic applications like autonomous vehicles and smart cities. However, a critical study reveals vulnerabilities in LTE and 5G core infrastructures that could lead to severe disruptions, including persistent denial-of-service (DoS) attacks affecting entire metropolitan areas.

Research Highlights

• A team of researchers uncovered 119 vulnerabilities across seven LTE and three 5G implementations. Their findings highlight critical flaws that allow attackers to exploit weaknesses in Mobility Management Entity (MME) or Access and Mobility Management Function (AMF) components, which manage device connectivity in cellular networks.
• These flaws, which range from memory management issues to improperly handled malformed packets, could persistently disrupt cellular communications such as phone calls, messaging, and data services on a massive scale. According to the researchers, attackers could trigger these disruptions by sending a single, small, malformed packet to the network.

Attack Mechanisms

• The vulnerabilities present two primary attack vectors:
• Remote Exploitation via Malformed Packets
• Base Station Exploitation

Expanding Attack Scope with Wi-Fi Calling

• “These attacks could once be contained geographically, but now any internet-connected device could theoretically disrupt cellular services in a faraway city,” the researchers warned.

Open Source and Commercial Implementations

• The study analyzed several LTE and 5G core implementations, including open-source and commercial solutions:
• LTE Implementations: Open5GS, Magma, OpenAirInterface, Athonet, SD-Core, NextEPC, and srsRAN.
• 5G Implementations: Open5GS, Magma, and OpenAirInterface.
• Every implementation tested had vulnerabilities, emphasizing that both open-source and proprietary cellular cores are susceptible. Out of the 119 identified flaws, 93 were assigned CVE identifiers, highlighting their criticality.

Lack of Response from Some Vendors

The research team attempted to disclose the vulnerabilities to affected vendors, but responses were inconsistent. While most vendors acknowledged and started addressing the flaws, two notable exceptions NextEPC and SD-Core failed to respond to the disclosure efforts. Even attempts to notify these maintainers through alternative channels, such as GitHub, were unsuccessful.

This lack of response from certain vendors raises concerns about the readiness of some LTE and 5G implementations to address security issues promptly.

Research and Mitigation Efforts

1. The researchers have documented their findings in a paper titled “RANsacked” (PDF), providing technical insights into the vulnerabilities and the fuzzing framework used to identify them. The study highlights the importance of comprehensive testing for cellular network components and the risks posed by unpatched flaws.
2. The paper also describes how threat actors can exploit these vulnerabilities to launch persistent DoS attacks against city-wide networks. The researchers suggest a two-pronged approach for mitigation:
3. Enhanced Fuzz Testing: Cellular network components must undergo rigorous fuzz testing to identify vulnerabilities before deployment. This proactive approach could help detect flaws before attackers exploit them.
4. Vendor Responsibility: Vendors must prioritize security patching and collaborate with researchers to address reported flaws. Unresponsive vendors leave their implementations vulnerable to exploitation, which could have catastrophic consequences for cellular networks.

The Broader Implications

• The findings underline the fragility of modern cellular infrastructure. In the interconnected world of LTE and 5G, where networks power essential services such as emergency communications, transportation systems, and healthcare, prolonged DoS attacks could have far-reaching consequences.
• Moreover, the transition to 5G while promising higher speeds and improved reliability also introduces new complexities and vulnerabilities. As 5G networks proliferate, their reliance on smaller, easily accessible base stations and virtualized network components creates additional entry points for attackers.

Call to Action

1. The research serves as a wake-up call for governments, network operators, and equipment manufacturers. To prevent large-scale disruptions:
2. Network Operators: Must implement strict monitoring and anomaly detection systems to quickly identify and mitigate malicious activity.
3. Vendors: Should adopt secure development practices and promptly patch vulnerabilities.
4. Policymakers: Should enforce stringent security standards for LTE and 5G implementations to ensure the resilience of critical communication networks.

Conclusion

The vulnerabilities uncovered in LTE and 5G core infrastructure highlight the need for a collective, industry-wide effort to bolster the security of cellular networks. With the potential to disrupt city-wide connectivity, these flaws pose a significant threat to public safety, economic activity, and national security.

As LTE and 5G continue to underpin essential services, prioritizing their security is no longer optional it is imperative. The next wave of innovation in cellular networks must go hand-in-hand with robust security measures to safeguard the connected world.