By James Neilson, SVP of Global at OPSWAT
Healthcare depends on speed, trust, and constant information sharing.
Referrals, discharge summaries, medical images, test results, and patient-uploaded documents arrive continuously across multiple systems and networks to ensure services aren’t disrupted.
Very few clinicians will think twice about opening any of the dozens of files they receive every day, because patient care comes first and delays are not an option.
But this everyday occurrence has become one of the most reliable entry points for cybercriminals seeking to hold healthcare providers to ransom and steal patient data.
A single malicious document or link can be enough to compromise critical systems, disrupt clinical services and put patient safety at risk.
The risks of file sharing
File sharing is fundamental to healthcare delivery. Every patient journey relies on information moving quickly between organisations that often operate on entirely separate networks.
Hospitals receive referrals from GPs, imaging from specialist clinics, documentation from insurers and, increasingly, files uploaded directly by patients through portals and apps.
Many of these files originate from unmanaged personal devices and external systems that healthcare providers do not control.
This creates a steady flow of “uncontrolled” files. While they are a core part of daily healthcare routines, they arrive without the security assurances organisations rely on internally.
Malicious files are an issue for most industries, but the strained resources and constant time pressure of healthcare create an environment where files are trusted by default.
Attackers understand this well. Rather than relying on obvious phishing tactics more likely to be noticed or caught by email security solutions, they increasingly hide malicious content inside the very files clinicians need to open in order to carry out routine care.
How malicious files hide in plain sight
File-based attacks are nothing new, but they have become far more subtle in recent years.
James Neilson
Malware rarely arrives as an obviously suspicious attachment and is instead more likely to be embedded inside common formats such as PDFs, images, and documents that appear, at face value, to be entirely legitimate.
A discharge summary, referral letter, or set of scans may contain hidden elements designed to trigger the moment the file is opened.
Often, the file itself is only the first step, quietly establishing access that attackers can exploit later for ransomware or data theft.
This approach works because it exploits the trust of the reader. Clinicians are not being deceived into opening something unusual; they are simply opening the files they expect to receive, very often at moments when time is of the essence.
Why healthcare providers struggle to stop these threats
Healthcare organisations are not ignoring cyber risk. Instead, in many cases, they are constrained by the very measures designed to protect patient confidentiality.
Strict end-to-end encryption ensures sensitive medical data cannot be intercepted in transit.
However, it also creates a blind spot. Unlike most other industries, healthcare organisations are often legally prevented from inspecting encrypted files as they pass through the network.
As a result, files can travel securely through the perimeter and only become visible once they reach core clinical systems.
The next step is usually a clinician opening the file, at which point any hidden malware can execute immediately.
Traditional security tools struggle to compensate for these limits. Many hospitals rely on a single antivirus engine, often installed by default.
Attackers deliberately design malware to evade the most common security protection, gaining a dangerous advantage. They can keep trying and only need one file to succeed, while healthcare organisations need every file to be secure every time.
When one infected file disrupts an entire healthcare ecosystem
Once a malicious file is opened, the impact can be immediate, often rippling through the entire organisation and beyond.
Access to patient records, imaging systems, medication charts, and scheduling tools can be lost. Surgeries may be postponed, and emergency departments may be forced to divert patients.
Hospitals can be forced to pause operations while incidents are investigated.
However, care needs to continue around the clock, so even short disruptions can have serious consequences for safety and patient outcomes.
Attacks that take days or weeks to resolve can have an impact that stretches for months after the initial incident.
The effects also extend beyond individual organisations because healthcare networks are deeply interconnected.
When a provider suffers a confirmed malware incident, external providers and partners may be forced to disconnect as a precaution to prevent further spread.
In some cases, insurers may suspend connections until the provider can prove it is infection-free.
For clinics, this can be operationally and financially devastating as invoices cannot be processed, payments are delayed, and costs continue to mount. Smaller providers may only have weeks before the cashflows dry up.
Why checking files before access is the only reliable defence
Given the volume and variety of files entering healthcare systems, the safest assumption is that any file could be malicious until proven otherwise.
The most effective point of control is before a clinician ever opens a file.
Files need to be automatically inspected and cleaned as soon as they arrive inside the environment, without adding friction to clinical workflows.
If additional security controls slow staff down, they may be bypassed. Therefore, protection must operate quietly in the background.
Content Disarm and Reconstruction (CDR) is one of the most effective tools here, as it sanitises all files to remove any active content, while keeping the files usable.
By removing active or hidden content while preserving the information clinicians need, organisations can ensure that staff interact only with safe versions of files.
This approach protects systems without expecting clinicians to act as security experts.
Another important layer of security is the data diode, a hardware unit that enforces unidirectional data flow.
This provides an extra layer of defence against common tactics such as data exfiltration and command and control (C2).
Making file security part of patient safety, not an IT afterthought
As healthcare becomes more digital and interconnected, the risks associated with file sharing will continue to grow.
File security is not just an IT concern; it is a fundamental cornerstone of patient safety and operational resilience.
Ensuring files are safe before they are accessed helps protect care delivery by ensuring clinical staff can do their jobs and keeps the wider healthcare ecosystem stable.
In a sector that never stops, preventing that single click from becoming a major incident is no longer optional.
