How Do Security Breaches Occur? 7 Causes Banks Must Address

What Is a Security Breach?

A security breach occurs when an unauthorized party gains access to protected systems, networks, or data by bypassing security controls. While the terms “security breach” and “data breach” are often used interchangeably, they describe different stages of the same problem. A security breach is the intrusion, while a data breach is the outcome when sensitive information is accessed.

For financial institutions, breaches can target three areas of information security:

• Confidentiality breaches expose sensitive customer data
• Integrity breaches alter data without authorization
• Availability breaches disrupt access to critical systems

Banks and credit unions face elevated risk because they hold the kind of data attackers prize: personally identifiable information tied directly to financial accounts. Regulators recognize this, which is why frameworks like the GLBA Safeguards Rule exist.

7 Leading Causes of Security Breaches at Financial Institutions

Most data breach causes fall into a handful of categories. Understanding each one helps your institution prioritize where to invest its security resources.

Human Error and Employee Negligence

Employees remain the single largest source of security breaches at financial institutions. This includes:

• Misdirected emails containing sensitive customer data
• Misconfigured cloud storage buckets
• Lost or stolen laptops
• Accidental deletion of access controls

The Verizon 2025 DBIR finds that roughly 60% of breaches involve a human element, whether through error, manipulation, or malicious misuse. In banking, where staff handle regulated data daily, even routine mistakes carry outsized consequences.

Phishing and Social Engineering

Phishing attacks target employees through deceptive emails, text messages, or phone calls designed to steal credentials or trick staff into authorizing fraudulent transactions. Spear phishing poses particular danger to financial institutions because attackers research their targets using publicly available information about bank officers and organizational structure.

Business email compromise (BEC) schemes, where attackers impersonate executives or vendors to authorize wire transfers, have cost financial institutions billions globally. These attacks succeed not through technical sophistication but through exploiting trust and urgency.

Malware and Ransomware Attacks

Malware reaches financial institution networks through email attachments, compromised websites, infected USB drives, and increasingly through software supply chain attacks. Once inside, malware can harvest credentials, log keystrokes, or establish persistent backdoor access.

Ransomware represents a particularly acute threat. The Verizon 2025 DBIR found ransomware appearing in 44% of breaches, up from 32% the prior year. These attacks encrypt critical systems and demand payment for decryption keys, paralyzing banking operations.

Insider Threats

Not every breach comes from outside the organization. Insider threats fall into two categories:

• Negligent insiders who cause breaches through carelessness
• Malicious insiders who deliberately misuse their access for personal gain

In banking environments, privileged users present the highest insider risk. An employee with direct access to customer databases and wire transfer systems can exfiltrate data or initiate unauthorized transactions in ways that bypass perimeter defenses.

Weak or Stolen Credentials

Compromised credentials remain one of the most common data breach causes. Password reuse across personal and professional accounts, weak password policies, and the absence of multi-factor authentication (MFA) all contribute.

Credential stuffing attacks, where attackers use stolen username-password pairs from previous breaches to access other accounts, are effective precisely because people reuse passwords.

Third-Party Vendor Vulnerabilities

Financial institutions rely on dozens of third-party vendors for core banking platforms, payment processing, cloud hosting, cybersecurity tools, and more. Each vendor relationship extends your attack surface. When a vendor suffers a breach, your institution’s data can be exposed without your own systems ever being directly compromised.

The OCC, FDIC, and Federal Reserve issued interagency guidance on third-party risk management in June 2023, requiring banks to conduct due diligence and ongoing monitoring of vendor security practices. Despite this, vendor-originated breaches continue to rise as supply chain attacks grow more sophisticated.

System Misconfigurations and Unpatched Software

Misconfigured firewalls, open database ports, overly permissive cloud storage settings, and delayed software patches create vulnerabilities that attackers actively scan for. Automated tools can identify unpatched systems within hours of a vulnerability being publicly disclosed.

Legacy systems present a particular challenge for financial institutions. Many banks still run core processes on aging infrastructure that may no longer receive security updates. Each unpatched system is an open door that automated attack tools can find and exploit with minimal effort.

Real-World Security Breach Examples in Banking

Recent security breach examples from the financial sector put concrete numbers behind the categories above.

Capital One (2019)
A misconfigured web application firewall allowed a former cloud services employee to access over 100 million customer records, including Social Security numbers and bank account details. According to American Banker, the breach resulted in an $80 million fine from the OCC and a $190 million class action settlement.

Evolve Bank & Trust (2024)
The LockBit ransomware group attacked Evolve Bank after an employee clicked a malicious link, exfiltrating data on 7.6 million individuals including names, Social Security numbers, and account information. According to Evolve Bank, the breach exposed downstream risk for fintech partners including Affirm, Mercury, and Wise.

How to Prevent Security Breaches at Your Financial Institution

Identifying the causes is the diagnostic step. What follows is a layered defense strategy that addresses each breach vector above.

• Employee security awareness training
  This should be continuous, not annual. Phishing simulations, role-based training on data handling, and clear reporting procedures reduce the human error that drives most breaches.
• Multi-factor authentication and access controls
  These limit the damage when credentials are compromised. Enforce MFA for all remote access, privileged accounts, and customer-facing systems. Apply the principle of least privilege so staff access only the data their role requires.
• Regular vulnerability assessments and penetration testing
  Quarterly vulnerability scans and annual penetration tests keep your security posture current.
• Vendor risk management programs
  These must include security assessments during onboarding, contractual security requirements, and ongoing monitoring of vendor compliance.
• Incident response planning
  Use issue tracking software and test your plan through tabletop exercises at least annually and make sure it addresses notification requirements under state breach laws, GLBA, and examiner expectations.

How Risk Management Software Strengthens Prevention

A quarterly risk assessment captured in a spreadsheet cannot keep pace with threats that evolve weekly. Gaps in security controls go undetected between reviews and those gaps are exactly what attackers and examiners both find.

AI-powered risk management platforms like Predict360 provide the continuous monitoring that regulators increasingly expect. These platforms centralize risk identification, automate control testing, flag emerging threats, and maintain a real-time view of your institution’s risk profile. See how our solution compares to other platforms in the GRC sphere.

For financial institutions preparing for examinations, this kind of integrated approach provides the documented evidence examiners look for: that your institution not only identifies cybersecurity risks but actively monitors and mitigates them on an ongoing basis.

Frequently Asked Questions