When we think of cyberattacks on critical infrastructure, the focus often turns to ransomware campaigns or state-sponsored exploits targeting industrial control systems. But some of the most effective intrusions don’t begin with a sophisticated exploit. They start with a file.
What is a File-Bourne Attack in an IT-OT Environment?
File-borne attacks are a growing threat vector that exploit file movement between IT and OT networks to deliver malware into critical infrastructure. In modern converged IT-OT environments, a file-bourne attack occurs when a malicious file moves from a corporate IT network into an OT (operational technology) environment. Once inside, it can disrupt production, trigger downtime, or compromise sensitive processes.
With IT-OT integration and remote connectivity expanding the attack surface, securing file movement has become a frontline priority for defenders of critical infrastructure.
The Threat to Critical Infrastructure
Critical operations depend on file transfers for software updates, vendor deliveries, engineering drawings, and sensor data. Unfortunately, these trusted file exchanges are increasingly used as vehicles for malware.
Attackers exploit common file transfer pathways:
- USB drives and laptops carried by contractors or employees
- Shared cloud storage syncing files into OT environments
- Email attachments that slip past traditional filters
- Unmanaged file transfer workflows between business and operational domains
According to SANS, 27% of ICS security professionals identified transient devices like USBs as a top malware infection vector in OT, while 33% of ICS incidents originate from internet-accessible devices and remote services. The evidence is clear: IT-OT file flows are among the most exposed pathways in modern infrastructure.
How a File-Borne Attack Works
A typical file-borne attack moves step by step from IT into OT:
- Payload Embedded: Malware is hidden in a legitimate-looking file, such as a PDF, update package, or engineering project file.
- File Originates in IT: It enters the organization through email, a supplier portal, or a cloud collaboration tool.
- Transfer from IT to OT: The file crosses into OT through a network bridge, removable media, or even a data diode if not properly inspected.
- Execution in OT: Once opened or executed, the malware detonates, disrupting operations or enabling data theft.
Real-world parallels:
- Stuxnet spread through infected USB drives that bypassed air gaps.
- TRITON was delivered via malicious engineering files.
- MOVEit exploitation showed how file transfer systems themselves can become a direct target.
In each case, a multi-layered secure file transfer process could have neutralized the malicious payload, enforced zero-trust policies, and ensured files were sanitized before entering critical systems.
Impact on Critical Infrastructure
When malicious files cross from IT to OT, the consequences reach far beyond digital damage:
- Operational Downtime: Halted production lines, disrupted services, outages.
- Physical Damage & Safety Risks: Manipulated controls or corrupted updates can put human lives at risk.
- Compliance Violations: Failures to meet NIST, NIS2, HIPAA, or PCI mandates can lead to regulatory fines and license issues.
- Reputational Harm: Lost customer and partner trust after a public incident.
With 76% of industrial organizations reporting cyberattacks in OT environments (ABI/Palo Alto, 2024), the need for resilient defenses is urgent.
Defense Strategies for IT-OT File Flows
Stopping file-borne attacks requires more than encrypted transport. A resilience layer must be embedded directly into every transfer. Key strategies include:
- Multi-Layered Inspection: OPSWAT technologies like Metascan™ Multiscanning, Deep CDR™, Adaptive Sandbox, and File-Based Vulnerability Assessment detect, disarm, or detonate malicious files before they enter OT.
- Zero-Trust Enforcement: RBAC (role-based access controls), supervisory approvals, and policy-driven workflows prevent unauthorized or unsanctioned transfers.
- Governance and Visibility: Immutable audit trails and centralized dashboards provide oversight and compliance assurance.
How OPSWAT delivers this:
- MetaDefender Managed File Transfer™ automates secure, governed file flows across IT, OT, and cloud.
- MetaDefender Kiosk™ sanitizes files from USBs, laptops, and contractors before they reach sensitive networks.
- MetaDefender NetWall® Data Diode enforces unidirectional, policy-controlled transfers to protect OT from inbound threats.
Together, these solutions create a secure transfer pathway that ensures every file is verified, sanitized, and controlled before crossing domain boundaries.
Real-World Lessons from File-Borne Attacks
- Infected USB drives can be blocked by MetaDefender Kiosk through sanitization and policy enforcement before reaching OT assets.
- Engineering workstation files from lower-trust sources are inspected by MetaDefender Managed File Transfer and subject to policy enforcement to block malicious or noncompliant content before reaching safety systems.
- Exploitation of MFT platforms demonstrates that multilayer inspection, policy enforcement, and auditable governance must be embedded in file transfer solutions.
Each case underscores the same point: resilient file transfer is not optional—it is essential.
Next Steps: Build Resilience at the File Layer
File-borne attacks will continue to evolve as IT and OT networks converge. The most effective defense is to secure every file, across every vector, whether it moves over the network, across domain boundaries, or through transient devices.
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