Four recent cyberattack cases targeting businesses | Lessons learned from unauthorized access and data breaches in the third week of July 2026

Four key cases emerge from security incidents reported by Japanese companies during the week of July 14-21, 2026. Many companies suffered simultaneous damage from system failures due to unauthorized access, data breaches, and ransomware attacks. The common thread in these cases is a combination of vulnerabilities in internal controls and sophisticated attack techniques from external sources. It is necessary to raise security awareness throughout organizations and strengthen prevention, detection, and rapid response.

Unauthorized access to Murata Manufacturing's IT environment, resulting in the leakage of customer information.

Murata Land & Building Co., Ltd., a subsidiary of Murata Manufacturing Co., Ltd., announced on July 13th that it had experienced unauthorized access to its IT environment. A report dated July 15th, 2026, revealed that customer information for automobile insurance may have been leaked externally due to unauthorized access to Murata Manufacturing's IT environment. The scale of the damage is expanding, and the company is continuing its investigation.

Unauthorized access to Nichirei's systems has caused a system failure, severely impacting logistics operations.

Nichirei Corporation announced on July 13th that it had experienced a system failure due to unauthorized access. The company group's systems were affected, significantly impacting refrigerated warehouse receiving and shipping operations and frozen food shipment operations. This incident demonstrates that not only B2C but also B2B logistics companies can suffer serious damage, raising concerns about ripple effects across the entire supply chain.

KDDI's email system for ISP operators leaked over 14 million email addresses and passwords.

KDDI Corporation has been continuously releasing detailed information as of July regarding the unauthorized access to its email system for ISP operators, which it announced on June 23rd. Up to 14.22 million email addresses and passwords may have been leaked, making this the largest data breach in Japan's history. The incident has had a ripple effect on multiple carriers, including JCOM, @nifty, BIGLOBE, and Chubu Telecommunications.

Unauthorized access to Aflac Life Insurance leads to the loss of personal information of approximately 4.38 million customers.

Aflac Life Insurance Co., Ltd. announced on June 30th that it had experienced unauthorized access to its systems, revealing that the personal information of approximately 4.38 million customers may have been leaked. Unauthorized access to financial institutions leads to a significant decline in customer trust. The company is continuing its investigation and has released several updates.

Five specific cybersecurity measures that should be implemented on the ground now

[1] Immediate Review of Authority Management and Access Control Many of this week's incidents started with unauthorized access spreading laterally after infiltrating the internal network. For all systems, verify the principle of least privilege for user accounts, service accounts, and administrator privileges in a monthly inventory. In particular, immediately delete accounts of employees who have left or transferred.

[2] Strengthen Email Security and Make Multi-Factor Authentication (MFA) Mandatory Intrusions into email systems, such as those at KDDI and Aflac, started with the leakage of authentication information. Set the default expiration date to "90 days" and apply a strong password policy. Implement multi-factor authentication on all systems, and complete the introduction of MFA to email accounts this month.

[3] Immediate Development of Backup and Recovery Plans for Core Systems Incidents that bring entire operations to a halt, such as the Nichirei system failure, are increasing. For critical business systems, conduct backup retrials (recovery tests) at least once a month and clearly define recovery time objectives (RTOs). Begin multi-layered backup operations using cloud storage and on-premises.

[4] Security Checks for Subcontractors and Supply Chains: Past cases of email misdelivery have shown that damage is frequently occurring through subcontractors. Check the security measures of your subcontractors, as well as your own company, on a quarterly basis, and clearly state the deadline for vulnerability remediation in the contract. Let's start the movement to unify security standards across the entire supply chain starting this week.

[5] Clarification of Incident Response System and Notification Procedures: The initial response to a customer information leak will affect a company's credibility. All departments should develop an incident response plan that defines "what happened," "who to report to," and "at what stage to notify external parties," and conduct practical training once a month. Joint exercises including legal, public relations, and management are necessary.

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Utilizing Microsoft Defender for Endpoint, we continuously monitor endpoints running Windows, macOS, Linux, and other operating systems. We detect and analyze suspicious behavior and signs of cyberattacks on endpoints in real time, supporting incident response activities such as threat hunting, forensic investigations, containment, and recovery.

[ThreatIDR] Early detection and rapid response to threats through multi-layered defense. It instantly detects lateral spread within the network and information leakage to the outside using multiple sensors and machine learning. By detecting threats in the early stages of unauthorized access, it can prevent the damage from spreading to email systems and main systems. 24/7 monitoring, analysis, and response significantly reduces average response time.

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1. Unauthorized access to Murata Manufacturing's IT environment, resulting in the leakage of customer information.

https://www.murata-mlb.co.jp/2026/07/10/%e6%9d%91%e7%94%b0%e8%a3%bd%e4%bd%9c%e6%89%80it%e7%92%b0%e5%a2%83%e3%81%b8%e3%81%ae%e4%b8%8d%e6%ad%a3%e3%82%a2%e3%82%af%e3%82%bb%e3%82%b9%e3%81%ab%e3%82%88%e3%82%8b%e5%80%8b%e4%ba%ba%e6%83%85%e5%a0%b1/

2. "System failure due to unauthorized access to Nichirei affects refrigerated warehouse receiving and shipping operations and frozen food shipment operations" https://www.nichirei.co.jp/news/2026/512.html

3. "Unauthorized access to KDDI's email system for ISP operators may have resulted in the leakage of up to 14.22 million email addresses and passwords" https://newsroom.kddi.com/news/assets/2026/kddi_nr_s-73_4619/kddi_nr_s-73_4619_pdf_01.pdf

4. "Aflac Life Insurance suffers unauthorized access, leaking customer information of approximately 4.38 million people."

https://www.aflac.co.jp/static/corp/profile/news/2026/20260630.pdf

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✦ Finally

Thank you for reading this far.

We at PIPELINE Corporation are a group of experts specializing in cybersecurity and threat intelligence.

We face threats together with our customers on-site every day.

"Even if we have a specialized team within the company, we lack the resources," "We don't know where to start," and "We want to prepare realistically, assuming we will be attacked."

We receive many inquiries like this. Regardless of the size of the company, the current situation is that weak points in defenses are easily targeted.

Furthermore, trying to handle everything internally inevitably makes it easier for things to be overlooked.

That's why we focus on practical methods that are useful in the field, rather than idealistic theories, and propose a small-scale, easy-to-implement approach. Even "a small step within your capabilities" can make a big difference in safety.

If you have any concerns at all, please feel free to contact us. Let's work together to find the quickest way to strengthen your security.