INSPECTING ARCHIVED INTELLIGENCE (OUTDATED VERSION).

Nikkei Admits Millions of Records Stolen After Third Breach This Month

| 2026-10-21 15:00 HIGH HIGH DATA BREACH
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Executive Summary
AI-generated
On October 7, Nikkei reported a data breach in which 1.83 million records were stolen, with around 150,000 containing personal identifiable information such as names, email addresses, and phone numbers. The breach involved unauthorized access to a cloud service used for system development, but no evidence has been found that the leaked data was misused. Nikkei is now working to assess the extent of the damage and find the cause, contacting all those whose data has been affected. This incident follows two previous breaches in late July, which compromised employees' Microsoft 365 business software accounts and accessed personal information belonging to employees and partners.
Technical Mitigations AI-generated
• Disable credentials used in the cloud service involved in the breach. • Regularly review account permissions and monitor for suspicious login activity to prevent unauthorized access. • Implement multi-factor authentication to significantly reduce the risk of unauthorized access.
Intelligence Metadata
Actors / Malware / CVEs / Campaigns
Target & Sectors
NORTH_AMERICA NORTH_AMERICA EMEA EMEA
Incident Timeline
‎May 2022
Nikkei admitted to having millions of records stolen following a data breach that occurred after the compromise of its Slack account in November.
tactic Data Breach
Looking further back, in May 2022, the firm revealed that it had fallen victim to a ransomware attack, while, in November last year, it disclosed a data breach that was caused by the compromise of a Slack account.
tactic Ransomware
Looking further back, in May 2022, the firm revealed that it had fallen victim to a ransomware attack, while, in November last year, it disclosed a data breach that was caused by the compromise of a Slack account.
organisation Slack
Looking further back, in May 2022, the firm revealed that it had fallen victim to a ransomware attack, while, in November last year, it disclosed a data breach that was caused by the compromise of a Slack account.
organisation Google News
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organisation BlueSky
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‎2025/10/21
Threat actors used ransomware to target Nikkei, resulting in a data breach that exposed millions of stolen records.
tactic Data Breach
Looking further back, in May 2022, the firm revealed that it had fallen victim to a ransomware attack, while, in November last year, it disclosed a data breach that was caused by the compromise of a Slack account.
tactic Ransomware
Looking further back, in May 2022, the firm revealed that it had fallen victim to a ransomware attack, while, in November last year, it disclosed a data breach that was caused by the compromise of a Slack account.
organisation Slack
Looking further back, in May 2022, the firm revealed that it had fallen victim to a ransomware attack, while, in November last year, it disclosed a data breach that was caused by the compromise of a Slack account.
‎October 16
Threat actors used social engineering tactics to steal millions of records from Nikkei, which was reported as the company's third breach in a month.
‎2026/10/21
Threat actors exploited a website vulnerability to steal millions of records from Nikkei, which was subsequently reported by the company.
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‎2026/10/21
Nikkei has reported a data breach in which 1.83 million records, including sensitive personal information of employees and business partners, were stolen from its Microsoft 365 cloud service.
organisation Personal Information Protection Commission
It has also reported the incident to Japan's Personal Information Protection Commission, but has found no evidence that the leaked data has been misused in any way.
infrastructure Microsoft 365
Microsoft 365 business software accounts and accessed personal information belonging to employees and business partners.
organisation Microsoft
Microsoft 365 business software accounts and accessed personal information belonging to employees and business partners.
organisation EMEA at Huntress
The investigation and remediation approach clearly needs to widen beyond what’s been done so far," commented Muhammad Yahya Patel, vCISO and cybersecurity advisor for EMEA at Huntress.
organisation Nikkei
About 1.68 million items contained information that couldn't be used to identify an individual, Nikkei said, and no credit card information was leaked.
organisation CyberSmart
Implementing multi-factor authentication, regularly reviewing account permissions and monitoring for suspicious login activity can significantly reduce the risk of unauthorized access," commented Jamie Akhtar, CEO and co-founder of CyberSmart.
data_breach 1.83 records
" Of the 1.83 million records that were stolen, around 150,000 contained one or more name, email address, postal address, phone number, or date of birth.
data_breach 150,000 records
" Of the 1.83 million records that were stolen, around 150,000 contained one or more name, email address, postal address, phone number, or date of birth.
Tactical Metrics
Metrics
infrastructure
‎Microsoft 365
Affected Product
Microsoft 365 business software accounts and accessed personal information belonging to employees and business partners.
Metrics
data_breach
1,830,000
Records
" Of the 1.83 million records that were stolen, around 150,000 contained one or more name, email address, postal address, phone number, or date of birth.
Metrics
data_breach
150,000
Records
" Of the 1.83 million records that were stolen, around 150,000 contained one or more name, email address, postal address, phone number, or date of birth.
Intelligence Sources
IT Pro 2026-10-21