Inside the Volt Typhoon Cyberattack: How a Chinese APT Infiltrated U.S. Critical Infrastructure

In a campaign that has deeply rattled cybersecurity agencies and policymakers, a Chinese state-sponsored threat actor known as Volt Typhoon was discovered operating within U.S. critical infrastructure networks.

The breach is among the most extensive ever attributed to China, and what makes it especially alarming is not just the sectors affected: energy, transportation, water, and telecommunications, but the stealth, persistence, and strategic intent behind it.

Volt Typhoon didn’t aim to cause immediate disruption. Its purpose was to gain long-term access to critical infrastructure that could be leveraged for sabotage in future conflicts.

Understanding the Volt Typhoon Attack

Volt Typhoon is part of a broader shift in nation-state cyber operations: the movement from espionage to pre-positioning for physical disruption. Active since at least mid-2021, the group exploited internet-facing routers and firewalls, particularly those that were out-of-date or lacked proper patching, to gain initial access.

Once inside, Volt Typhoon did not deploy malware in the traditional sense. Instead, it used living-off-the-land (LOTL) techniques, leveraging built-in tools like PowerShell, WMI, and command-line utilities already present on target systems.

This method makes detection extremely difficult. Because no foreign binaries are introduced, the attack traffic blends into legitimate administrative activity. According to Microsoft and CISA, the group also established persistence using valid credentials, which may have been harvested via credential dumping tools or reused from previously compromised accounts. Once authenticated, Volt Typhoon quietly moved laterally across networks, mapping systems, accessing operational technology (OT), and creating long-term footholds.

Their focus was on infrastructure that would be critical in a time of geopolitical crisis. Analysts say this behavior aligns more closely with preparatory sabotage than surveillance, raising fears that the group’s real intent is to be ready to cripple infrastructure in the event of a military confrontation—most notably over Taiwan.

Tools and Techniques Used

The Volt Typhoon campaign did not involve sophisticated custom malware, which is precisely what makes it dangerous. Instead of attacking with tools that could be reverse-engineered or fingerprinted, they used what was already there.

Initial entry was achieved by exploiting known vulnerabilities in outdated small office/home office (SOHO) routers and firewalls. These devices often go unpatched for months or years in enterprise networks. Some compromised devices were used as proxies, allowing Volt Typhoon to route command-and-control (C2) traffic through compromised infrastructure globally, which helped mask the true origin of the attack.

Once inside a network, they used PowerShell scripts, netsh, nbtstat, and even Task Scheduler to maintain persistence and exfiltrate data. They avoided setting off alerts by forgoing malware installation and relying instead on credential abuse and the native administrative tools that every Windows machine has by default.

In one case reported by security researchers, Volt Typhoon remained undetected for nearly a year within the operational network of a Massachusetts power utility, highlighting how difficult it is to detect this style of attack without deep behavioral monitoring.

Timeline of Events

• Mid-2021: Security researchers first detect anomalous activity tied to a threat group later named Volt Typhoon. Initial intrusions are low-profile, focused on reconnaissance.

• Early 2022: The group escalates privileges in multiple U.S. transportation and energy sector networks.

• 2023: U.S. government agencies begin receiving threat intelligence suggesting long-term infrastructure compromise. By then, Volt Typhoon had embedded itself into dozens of networks.

• February 2024: The U.S. Department of Homeland Security and CISA publicly confirm Volt Typhoon’s infiltration of critical U.S. infrastructure, some of which had gone unnoticed for years.

• March 2024: Independent researchers detail the Massachusetts power utility case. Reports show the group had access to both IT and OT networks, including SCADA systems.

• April 2025: According to TechRadar, Chinese officials privately acknowledge involvement in the Volt Typhoon operations during a closed-door meeting with U.S. representatives, signaling a rare admission in cyber diplomacy.

Geopolitical Implications and Counteraccusations

The Volt Typhoon operation is not just a cybersecurity incident; it’s a geopolitical message. The ability to silently access and potentially disable civilian infrastructure during a conflict gives any state a powerful strategic edge.

In a mirrored accusation, China claimed in April 2025 that the U.S. National Security Agency (NSA) launched cyberattacks on critical infrastructure in Harbin during the Asian Winter Games. Chinese officials alleged that the U.S. targeted energy and transportation systems, using advanced techniques to exfiltrate sensitive information (AP News).

How These Attacks Work and How to Defend Against Them

What makes Volt Typhoon so dangerous is the low-and-slow approach. They rely on stealth, trust exploitation, and the absence of behavioral baselining. Unlike ransomware gangs or hacktivists, APTs like Volt Typhoon are not trying to draw attention. Their operations span years, not hours.

Defending against this type of threat requires a very different playbook:

• Network Segmentation: Separating IT from OT environments is crucial. Volt Typhoon specifically sought OT access, and segmentation with firewalls, VLANs, and protocol whitelisting can slow or stop lateral movement.

• Patch Management for Edge Devices: Many intrusions began by compromising unpatched routers and firewalls. Regularly auditing and updating internet-facing infrastructure is one of the most effective defenses.

• Zero Trust Architecture: Eliminating implicit trust within networks makes lateral movement harder. Every request should be authenticated, authorized, and encrypted.

• Behavior-Based Monitoring: Traditional signature-based detection will miss Volt Typhoon every time. What’s needed is monitoring that understands what normal looks like and flags deviations—tools that can detect misuse of PowerShell, unexpected credential use, or data moving where it shouldn’t.

• Hardware-Based Isolation: Where high-value environments must interface with external systems (e.g., remote monitoring for OT), technologies like data diodes can enforce one-way communication and prevent backflow into critical systems.

Final Thoughts

The Volt Typhoon cyberattack is a warning not just because of what was accessed but because of what hasn’t been done yet. The goal wasn’t to shut down the grid or crash a water supply system—it was to prove they could.

The threat from state-sponsored groups like Volt Typhoon will continue to grow. As geopolitical tensions rise, so does the likelihood that these digital footholds will be used not for espionage but for disruption. For governments and private sector operators of critical infrastructure, now is the time to act, not when the lights go out.

Contact DataFlowX today to explore how you can proactively protect your critical systems against modern-day cyber attacks.