Hacking the Cloud’s Backbone: Exploiting Undersea Internet Cables

SWARNALI GHOSH | DATE: JUNE 25, 2025

Introduction: The Invisible Lifelines of the Digital Age

Beneath the ocean’s surface, hidden from sight, lies the world’s most critical—and vulnerable—digital infrastructure: undersea internet cables. These fibre-optic veins carry over 95% of global internet traffic, connecting continents, powering financial markets, and enabling everything from video calls to military communications. In recent years, undersea cables have become a battleground in geopolitical conflicts, with nations like China and Russia accused of deliberate sabotage. Meanwhile, cybercriminals and state-sponsored hackers are continually finding new ways to exploit these cables, posing a threat to global connectivity. This article dives deep into the risks, real-world attacks, and the high-stakes race to secure the internet’s underwater backbone. Beneath the waves lies the literal backbone of our global digital world — nearly 1.4 million kilometres of undersea fibre-optic cables ferry virtually all internet traffic. Modern cloud services, military communications, financial markets, and our everyday social media run through these fragile cords, yet their vulnerabilities are often overlooked.

The Undersea Cable Network: How It Works

The Anatomy of a Submarine Cable: Modern undersea cables are marvels of engineering:

Rugged Yet Slender Design: Despite being only 1–20 cm thick—like a garden hose—subsea cables are reinforced with layers of steel and polyethylene. This tough exterior protects them from crushing pressure, anchors, and even shark bites in the deep ocean.

Blazing Fast Data Transmission: At their core, ultra-thin optical fibres transmit internet data across the globe at staggering speeds reaching 200 terabits per second. That’s nearly 700,000 times faster than the original transatlantic cable laid in the 19th century.

Signal Boosters Beneath the Waves: To maintain data integrity across thousands of kilometers, repeaters are placed every 50–100 km along the cable. These devices amplify the light signals to prevent weakening or loss during transmission.

Who Owns and Controls Them?

Big Tech's Grip on the Seafloor: Private tech giants like Google, Meta, Amazon, and Microsoft now own or lease around 50% of all undersea cable capacity. Their control gives them unprecedented power over the global internet infrastructure and data flows.

Telecom Alliances Shape the Future: Most new cable projects are led by international telecom consortia, such as the 2Africa Cable, backed by Vodafone, China Mobile, and Meta. These partnerships pool resources to expand internet access while asserting influence over global connectivity.

Rising Concerns Over China’s Cable Influence: HMN Technologies, formerly Huawei Marine, holds about 11% of the subsea cable market. Western nations worry this could be a vector for surveillance and state-sponsored cyber operations.

Critical dependency:

Lifelines of the Global Internet: Over 99% of the world’s internet traffic—spanning email, video calls, and data transfers—travels through undersea cables. They serve as the invisible backbone of our hyper-connected digital economy.

Critical to Cloud, Finance, and Communication: These cables enable cloud computing, real-time video conferencing, and seamless global financial transactions. A single disruption can affect everything from banking systems to emergency services and online businesses.

The Threats: From Accidents to Cyberwarfare

Physical Vulnerabilities:

Anchor strikes & fishing nets: Cause 70–80% of cable cuts. In March 2024, West Africa lost internet for days after seismic activity and ship anchors severed four cables.

Deep-sea sabotage: Russian spy ships like the Yanta are suspected of mapping cables for future attacks.

Choke points: The Red Sea’s Bab al-Mandab Strait (17 cables) and the South China Sea are high-risk zones.

Cyberattacks: The New Frontier:

Remote hijacking: Cable management systems (like ROADMs) are internet-connected, making them hackable.

Supply chain risks: Chinese repair ships (e.g., SBSS) could plant backdoors during maintenance.

Data interception: Unencrypted traffic passing through compromised cables can be tapped.

State-Sponsored Sabotage:

China vs. Taiwan: In 2023–2025, Chinese ships repeatedly cut cables near Taiwan’s Matsu Islands, causing weeks-long outages.

Baltic Sea incident: A Chinese vessel, Yi Peng, allegedly severed cables linking Sweden and Estonia in 2024.

Russia’s threats: Dmitry Medvedev (ex-Russian president) hinted at targeting undersea cables as retaliation.

Physical Threats: Accidents and Sabotage

Fishing trawlers & anchors: Roughly 70% of disruptions stem from maritime accidents—nets dragging across cable contours, poorly anchored ships, or dredging damage.

Natural disasters: Events like undersea earthquakes or volcanic eruptions (e.g., Tonga 2022) account for about 14% of the breaks.

Deliberate sabotage: Though less frequent, state-sponsored or espionage-driven actions occur, like Baltic Sea cuttings in late 2024 and the suspected involvement of the Chinese-flagged vessel Yi Peng. In the Baltic case, foreign ministers branded the incidents as “hybrid warfare”.

Cyber Intrusions: Remote Hacks and SDN Weaknesses

Cyber Risks in Cable Network Management:

SDN and Remote Systems Expose New Attack Surfaces: Modern undersea cables use Software-Defined Networking (SDN) and internet-connected remote management tools for efficiency. However, these interfaces are prime targets for cyberattacks, as they can be accessed and manipulated remotely.

State-Sponsored Exploits Threaten Data Sovereignty: A cyber breach targeting a Pacific cable in April 2022 was stopped by U.S. authorities, highlighting real-world risks. There are growing concerns that hostile states could exploit SDN flaws to reroute sensitive traffic through surveillance-friendly channels.

Technical Espionage: Tapping and Surveillance:

Landing-station access: These coastal hubs are soft physical targets—hackers could plant devices to tap data before light exits the cable.

Covert cable tapping: Historical NSA programs like BLARNEY and FAIRVIEW, plus British GCHQ’s cable taps, confirm that undersea tapping isn't just theoretical.

Emerging Threats: UUVs and Deep-Sea Tools

Weaponized drones: Uncrewed undersea vehicles (UUVs) could carry explosives or cutting tools to sever cables at depth.

Deep-sea cutting instruments: Reports suggest China has developed specialized cutters capable of slicing through thick cables silently.

Geopolitical Ripple Effects

Economic fallout: Disruptions affect trillions of dollars daily, with even minor outages costing millions per day.

National security stakes: Cloud providers, military communications, diplomatic channels—all rely on cable integrity. A coordinated attack could isolate regions, shut down dependencies like Taiwan or India, and weaken critical infrastructure.

The Fallout: Economic and Security Consequences

Financial Disruptions:

Real-World Losses from a Single Snip: When an undersea cable was severed near West Africa, Nigeria faced economic losses estimated at $590 million over just four days. The disruption crippled internet access, banking, and critical digital services across the region.

Trillions Ride on Fragile Threads: Every day, global banks transfer $3.9 trillion through these undersea networks. A coordinated cyber or physical attack could paralyze global financial markets within minutes.

Military and Political Risks:

NATO’s Strategic Dependence: NATO’s secure communications, intelligence sharing, and command systems rely heavily on undersea cables. If sabotaged during a conflict, it could severely impair military coordination and situational awareness.

Taiwan’s Fragile Connectivity: Taiwan is linked to the world by just 24 undersea cables, making it highly exposed to disruption. In a pre-invasion scenario, China could sever these links to isolate the island digitally and economically.

Protecting the Digital Lifelines: Solutions and Challenges

Redundancy and Resilience:

Redundancy Through More Cables: Building more undersea cables boosts global internet resilience by reducing reliance on any single route. The 46,000 km-long 2Africa Cable will loop around the continent, offering broader access and backup paths.

Satellites as Supplemental Support: Satellite systems like SpaceX’s Starlink and Amazon’s Project Kuiper can provide emergency connectivity. However, they currently lack the high bandwidth and low latency needed to fully replace undersea cables.

Cybersecurity Measures:

Encryption: A Missing Security Layer: End-to-end encryption can shield undersea cable traffic from interception and surveillance.Despite the risks, a significant number of undersea cables still transmit data without encryption, exposing them to potential surveillance.

FCC Steps Up Oversight: The U.S. Federal Communications Commission now mandates that cable operators file cybersecurity risk assessments. They must also vet and audit third-party vendors—especially those with foreign ties—to bolster national security.

Geopolitical Strategies:

U.S. Pushback Against Chinese Infrastructure: The U.S. has blocked several undersea cable projects connecting to Hong Kong, citing national security risks. Officials fear these links could enable Chinese surveillance and data interception.

NATO Defends the Digital Seafloor: In response to rising threats, NATO has ramped up naval patrols near key undersea cable routes. It’s also increasing intelligence sharing on suspicious submarine activity, particularly from Russia.

Smart Cables for a Safer Seabed:

Real-Time Anomaly Detection: Modern undersea cables are embedded with distributed sensors that monitor for vibrations, pressure changes, and tampering. These sensors can instantly detect unusual activity, like a trawler dragging an anchor or a seismic event.

Faster Fault Location and Repair: When a fault occurs, smart sensors help pinpoint the exact location of the damage along thousands of kilometres. This precision drastically reduces repair times, restoring connectivity more quickly and efficiently.

Eyes in the Sky and on the Sea:

Satellite Surveillance Enhances Awareness: European systems like Galileo and Copernicus provide high-resolution satellite imagery and environmental data. They help track vessel movements and monitor undersea cable zones for potential threats or anomalies.

Maritime Data Integration Boosts Security: Integrating AIS ship tracking with maritime surveillance systems gives authorities live insights into vessel movements and potential threats. This layered monitoring helps detect suspicious activity near critical cable infrastructure.

Rapid Response to Undersea Threats:

EU Invests in Repair Readiness: The European Union plans to deploy specialized cable-repair ships, with a budget of around €400 million. These ships are designed to quickly address cable failures, reducing service interruptions and limiting financial damage.

NATO and Navies Step Up Surveillance: NATO's HEIST initiative focuses on improving the detection of hybrid threats by leveraging advanced, interconnected monitoring technologies. Meanwhile, national navies—like the UK Royal Navy—have intercepted suspicious activity near critical cables.

Cybersecurity Fortifications for the Seafloor:

Technical Safeguards for Infrastructure: Best practices include securing remote cable management systems and applying Software-Defined Networking (SDN) hardening. End-to-end encryption of cable traffic is also essential to prevent data interception and tampering.

Collaboration Through Threat Intelligence Sharing: Establishing public-private threat-sharing hubs—such as Information Sharing and Analysis Centres (ISACs)—is vital. These centres enable faster detection, response, and coordination against cyber and physical threats to cable systems.

Legal Shields and Diplomatic Deterrence:

Maritime Law as a Protective Framework: The United Nations Convention on the Law of the Sea (UNCLOS) grants undersea cables special protections in international waters. The agreement’s clauses can be used to protect critical infrastructure and support responses to acts of disruption or tampering.

Sanctions and Accountability Measures: Governments are increasingly imposing sanctions for deliberate cable damage, including actions by covert “shadow fleets.” Legal frameworks are evolving to hold state and non-state actors accountable for sabotage or negligence.

Conclusion: The Silent War Under the Sea

Undersea cables represent a critical vulnerability in today’s cloud-driven world. With the rise of cyber conflict, their protection goes far beyond simple maintenance—it’s a matter of global stability. From the digital isolation risks facing Taiwan to reports of Russian submarines near cable routes, the urgency is real. These cables are the physical infrastructure that powers the cloud, stretching across the seabed in a complex web that’s as much a geopolitical concern as a technological achievement. While accidental damage already disrupts millions, deliberate sabotage or cyber interference could seriously jeopardize global communications, economic systems, and national security.

Citations/References

1. Ratiu, A. (2025, January 16). Cyber defence across the ocean floor: The geopolitics of submarine cable security - Atlantic Council. Atlantic Council. https://www.atlanticcouncil.org/in-depth-research-reports/report/cyber-defense-across-the-ocean-floor-the-geopolitics-of-submarine-cable-security/

2. How hackers of submarine cables may be held liable under the Law of the Sea | Chicago Journal of International Law. (n.d.). https://cjil.uchicago.edu/print-archive/how-hackers-submarine-cables-may-be-held-liable-under-law-sea

3. Coker, J. (2025, June 24). Submarine cables are at growing risk of cyberattacks. Infosecurity Magazine. https://www.infosecurity-magazine.com/news/submarine-cables-risk-cyber-attacks/

4. Runde, D. F., Murphy, E. L., & Bryja, T. (2024). Safeguarding Subsea Cables: Protecting Cyber Infrastructure amid Great Power Competition. https://www.csis.org/analysis/safeguarding-subsea-cables-protecting-cyber-infrastructure-amid-great-power-competition

5. Information Warfare in the Depths: An Analysis of Global Undersea cable Networks | Proceedings - May 2023 Vol. 149/5/1,443. (2023, May 31). U.S. Naval Institute. https://www.usni.org/magazines/proceedings/2023/may/information-warfare-depths-analysis-global-undersea-cable-networks

6. Goud, N. (2024, December 18). UNSEEN Guardians: How submarine internet cables in deep seas thwart cyber attacks. Cybersecurity Insiders. https://www.cybersecurity-insiders.com/unseen-guardians-how-submarine-internet-cables-in-deep-seas-thwart-cyber-attacks/

7. Discovery, B. (n.d.). Subsea Secrets: spies, sabotage, and the global race for internet cables. Boundless Discovery. https://newsletter.boundlessdiscovery.com/p/subsea-secrets-spies-sabotage-and-the-global-race-for-internet-cables

Image Citations

1. Burgess, M. (2022, November 2). The most vulnerable place on the internet. WIRED. https://www.wired.com/story/submarine-internet-cables-egypt/

2. Austin. (2024, October 16). Safeguarding connectivity: The role of submarine cables and Deep-Sea emergency Services - global brands. Global Brands Magazine. https://www.globalbrandsmagazine.com/submarine-cables-deep-sea-emergency-services/

3. Staff, O. (2024, November 19). Undersea internet cable connecting Germany and Finland destroyed beneath the Baltic Sea, sabotage feared. OpIndia. https://www.opindia.com/2024/11/undersea-data-cable-germany-and-finland-destroyed-beneath-the-baltic-sea-sabotage-feared/

4. Conversation, & Conversation. (2024, April 2). Nearly all data that moves around the world goes through these undersea cables. Fast Company. https://www.fastcompany.com/91072728/internet-undersea-cables-data

5. Marlow, J. (2022, July 26). Undersea internet cables can detect earthquakes—and may soon warn of tsunamis. The New Yorker. https://www.newyorker.com/science/elements/undersea-internet-cables-can-detect-earthquakes-and-may-soon-warn-of-tsunamis