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Healthcare has been the most targeted critical infrastructure sector in the United States for two consecutive years, according to the FBI's 2025 Internet Crime Report. The attacks behind that ranking are not one thing. They range from ransomware that shuts down an entire health system to a single fraudulent invoice that moves money out the door, and the defenses that stop one often do nothing against another. Cybercriminals constantly evolve their tactics to gain unauthorized access to networks and launch cyberattacks. Organizations and individuals need to understand and defend against these cyber threats proactively.
Understanding the types of cybersecurity threats
Cybersecurity threats encompass a wide range of malicious activities that compromise the security and integrity of computer systems and networks. These threats can vary in complexity and impact, ranging from simple scams to highly sophisticated exploits:
Ransomware
Ransomware encrypts an organization's files and demands payment for the key. Modern groups add a second lever called double extortion, stealing a copy of the data before locking it so they can threaten publication even if the victim restores from backup. The Verizon 2026 Data Breach Investigations Report found ransomware present in 48% of confirmed breaches, the highest share in its 19-year run.
The February 2024 attack on Change Healthcare remains the largest healthcare breach on record. Attackers entered through a remote access portal with no multi-factor authentication, moved through the network, and exfiltrated data before deploying ransomware. A study published in JAMA Network Open documented roughly 100 million individuals affected and $2.4 billion in response costs, with disruption reaching about 80% of US providers and pharmacies.
Phishing and social engineering
Social engineering manipulates a person into taking an action that compromises security, and phishing is its most common form. The attacker does not break in. Someone lets them in, usually by entering credentials on a convincing fake login page.
In June 2025, the FBI and the Centers for Medicare and Medicaid Services jointly warned providers and patients about criminals impersonating legitimate health insurers by email and text, requesting reimbursement for services the recipient never received and harvesting medical records and financial details in the process.
Business email compromise
Business email compromise skips malware entirely. A criminal impersonates an executive, vendor, or business associate, then asks someone in finance to update payment details or approve a transfer. Because the message carries no attachment or malicious link, filters built to scan for those find nothing to flag.
The threat is big enough that HHS's Health Sector Cybersecurity Coordination Center published a dedicated briefing on business email compromise in healthcare, documenting how attackers research an organization's vendor relationships and billing cycles before sending a single message. Healthcare is exposed here because it processes high volumes of legitimate vendor payments, which gives a fraudulent request somewhere to hide.
Adversary-in-the-middle attacks
An adversary-in-the-middle attack, sometimes called AiTM, places the attacker between the user and the real login page. The victim sees a genuine sign-in, completes their MFA challenge normally, and the attacker quietly captures the session cookie, the small file a browser holds so a user does not re-authenticate on every click. With that cookie, the account is open without the password or second factor.
Tycoon2FA became the dominant AiTM platform selling this capability as a subscription service before an international takedown led by Microsoft and Europol disrupted it in March 2026. As BleepingComputer reported, the operators rebuilt within weeks. Healthcare's reliance on Microsoft 365 puts it squarely in the target set for kits built to defeat that platform's authentication.
Password attacks
Password attacks cover brute force, which guesses combinations at machine speed, and password spraying, which tries a few common passwords across many accounts to stay under the lockout threshold. Credential stuffing skips guessing altogether by reusing real logins stolen from earlier breaches.
On October 31, 2024, HHS OCR announced a settlement with Plastic Surgery Associates of South Dakota over a breach affecting 10,229 individuals. Investigators found the attacker had broken in through a brute-force attack on the practice's remote desktop protocol, then deployed ransomware across nine workstations and two servers. Unable to restore from backups, the practice paid roughly $27,000 in Bitcoin.
Denial-of-service attacks
A denial-of-service attack floods a website or system with traffic until it becomes unusable. The distributed version, DDoS, uses a botnet, meaning a network of compromised devices under an attacker's control, to generate that traffic from thousands of sources at once. These attacks rarely steal data, but they can take patient-facing systems offline for hours or days.
In January 2023, HHS HC3 issued an analyst note after the pro-Russian group KillNet claimed DDoS attacks against US hospital websites. Named targets included C.S. Mott Children's Hospital in Michigan, Atrium Health in North Carolina, and Buena Vista Regional Medical Center in Iowa. HC3 noted that while the damage is usually limited, outages can run for days and can also mask more serious intrusions happening at the same time.
Medical device and IoT attacks
Connected medical devices run firmware that often cannot be patched easily and were rarely designed with network security in mind. An infusion pump or patient monitor cannot simply be taken offline for maintenance the way a workstation can, which leaves known vulnerabilities open far longer than they would be elsewhere.
The FDA has issued repeated safety communications on this. In one, the agency warned that Medtronic MiniMed insulin pumps could be remotely accessed and controlled, leading to a recall. A 2026 review published in Frontiers in Digital Health analyzing FDA safety communications found remotely exploitable flaws in Fresenius Kabi infusion pumps that allowed alteration of device settings as though the attacker were an authenticated user, with roughly 1,200 pumps requiring hardware modification.
Insider threats
Not every threat comes from outside. Insider incidents cover both deliberate misuse by staff with legitimate access and the far larger category of well-intentioned errors made under pressure. Technical controls struggle here because the access itself is authorized.
Carnegie Mellon University Software Engineering Institute research, cited in Paubox's 2025 Healthcare Email Security Report, found that more than half of insider fraud incidents in healthcare involve theft of customer data. The Verizon 2026 DBIR separately placed insider involvement at 19% of healthcare incidents, a figure that has stayed stable enough to suggest a structural condition rather than a training problem.
Where the defenses actually overlap
Most of these categories share an entry point. Ransomware, business email compromise, adversary-in-the-middle attacks, and the credential theft feeding password attacks all begin, more often than not, with an email that reached someone's inbox.
That makes the inbound email layer the single highest-leverage place to intervene. Paubox's 2025 Healthcare Email Security Report found employees report only 5% of known phishing attempts to their security teams, so the message that starts the chain almost always arrives unflagged. Paubox's 2026 Healthcare Email Security Report tracked a 47% increase in attacks avoiding native email defenses in 2025, which says the filtering built into Microsoft 365 and Google Workspace is not catching what is being sent. Paubox Inbound Email Security uses AI to analyze sender behavior, message intent, and contextual signals rather than matching known-bad patterns, catching what signature-based tools miss before staff ever see it.
Learn more: Paubox Inbound Email Security
FAQs
What is a cyberattack?
A cyberattack is a deliberate exploitation of computer systems, technology-dependent enterprises, and networks. It involves unauthorized access, disruption, or theft of information from a targeted system or network.
How can individuals and organizations protect themselves from cyberattacks?
- Strong passwords: Use unique passwords for different accounts.
- Security software: Install and regularly update antivirus and antimalware software.
- Employee training: Educate employees about cybersecurity best practices.
- Regular backups: Regularly back up important data to a secure location.
How do cyberattacks impact healthcare operations and patient care?
- On average, cyberattacks take healthcare organizations offline for six hours, with smaller hospitals commonly being offline for 9 hours or more.
- 95% of identity theft happens because of stolen healthcare records.
