Access Denied: Assessing Physical Risks to Internet Access Networks


Alexander Marder, CAIDA / UC San Diego; Zesen Zhang, UC San Diego; Ricky Mok and Ramakrishna Padmanabhan, CAIDA / UC San Diego; Bradley Huffaker, CAIDA/ UC San Diego; Matthew Luckie, University of Waikato; Alberto Dainotti, Georgia Tech; kc claffy, CAIDA/ UC San Diego; Alex C. Snoeren and Aaron Schulman, UC San Diego


Regional access networks play an essential role in connecting both wireline and mobile users to the Internet. Today’s access networks support 5G cellular phones, cloud services, hospital and financial services, and remote work essential to the modern economy. Yet long-standing economic and architectural constraints produce points of limited redundancy that leave these networks exposed to targeted physical attacks resulting in widespread outages. This risk was dramatically shown in December 2020, when a bomb destroyed part of AT&T’s regional access network in Nashville, Tennessee disabling 911 emergency dispatch, air traffic control, hospital networks, and credit card processing, among other services.

We combine new techniques for analyzing access-network infrastructure deployments with measurements of large-scale outages to demonstrate the feasibility and quantify potential impacts of targeted attacks. Our study yields insights into physical attack surfaces and resiliency limits of regional access networks. We analyze potential approaches to mitigate the risks we identify and discuss drawbacks identified by network operators. We hope that our empirical evaluation will inform risk assessments and operational practices, as well as motivate further analyses of this critical infrastructure.

Open Access Media

USENIX is committed to Open Access to the research presented at our events. Papers and proceedings are freely available to everyone once the event begins. Any video, audio, and/or slides that are posted after the event are also free and open to everyone. Support USENIX and our commitment to Open Access.

@inproceedings {285431,
author = {Alexander Marder and Zesen Zhang and Ricky Mok and Ramakrishna Padmanabhan and Bradley Huffaker and Matthew Luckie and Alberto Dainotti and kc claffy and Alex C. Snoeren and Aaron Schulman},
title = {Access Denied: Assessing Physical Risks to Internet Access Networks},
booktitle = {32nd USENIX Security Symposium (USENIX Security 23)},
year = {2023},
isbn = {978-1-939133-37-3},
address = {Anaheim, CA},
pages = {6877--6892},
url = {},
publisher = {USENIX Association},
month = aug

Presentation Video