Microsoft, Google and Nikkei Inc.: Nikkei Hit by Cyberattack: 9,000 Spoofing Emails Sent, Unauthorized Login to Microsoft 365 – Users React: 'Isn't this serious?' 'This is malicious.'

Nikkei Hit by Cyberattack Targeting Microsoft 365 and Google Workspace Accounts

On October 4, Nikkei Inc. disclosed a cyberattack targeting employee Microsoft 365 accounts, during which an unauthorized third party gained access. The breach resulted in approximately 9,000 suspicious emails impersonating employees being sent from compromised accounts. Nikkei responded by resetting passwords and confirmed no further unauthorized logins since the incident. Affected recipients were contacted individually to request deletion of the fraudulent emails.

Simultaneously, Nikkei revealed that Google Workspace accounts had experienced unauthorized external logins as early as late July, potentially exposing email addresses and names of 1,646 individuals, including employees and business partners. The breach was detected in early August after Google issued a notification. Passwords were reset, and no further unauthorized access has been confirmed.

The incident sparked widespread concern on social media, with users on X (formerly Twitter) highlighting the severity of the attack and questioning corporate security measures. Many noted the exploitation of Nikkei’s credibility in the phishing campaign, underscoring the growing threat of sophisticated cyberattacks targeting high-profile organizations.

Source: https://ascii.jp/en/elem/000/004/439/4439859/

Microsoft TPRM report: https://www.rankiteo.com/company/microsoft-security

Google TPRM report: https://www.rankiteo.com/company/googleworkspace

Nikkei Inc. TPRM report: https://www.rankiteo.com/company/nikkei

"id": "nikgoomic1791189711",
"linkid": "nikkei, googleworkspace, microsoft-security",
"type": "Vulnerability",
"date": "10/2026",
"severity": "25",
"impact": "1",
"explanation": "Attack without any consequences"

{'affected_entities': [{'customers_affected': '1,646 individuals (employees '
                                              'and business partners)',
                        'industry': 'Media',
                        'name': 'Nikkei Inc.',
                        'type': 'Corporation'}],
 'attack_vector': ['Compromised Accounts', 'Credential Theft'],
 'customer_advisories': 'Affected recipients contacted individually to request '
                        'deletion of fraudulent emails',
 'data_breach': {'number_of_records_exposed': '1,646',
                 'personally_identifiable_information': ['Email addresses',
                                                         'Names'],
                 'sensitivity_of_data': 'Low to Medium',
                 'type_of_data_compromised': ['Email addresses', 'Names']},
 'date_detected': '2023-10-04',
 'date_publicly_disclosed': '2023-10-04',
 'description': 'Nikkei Inc. disclosed a cyberattack targeting employee '
                'Microsoft 365 accounts, during which an unauthorized third '
                'party gained access. The breach resulted in approximately '
                '9,000 suspicious emails impersonating employees being sent '
                'from compromised accounts. Simultaneously, Google Workspace '
                'accounts experienced unauthorized external logins, '
                'potentially exposing email addresses and names of 1,646 '
                'individuals, including employees and business partners.',
 'impact': {'brand_reputation_impact': 'Widespread concern on social media',
            'data_compromised': ['Email addresses', 'Names'],
            'systems_affected': ['Microsoft 365', 'Google Workspace']},
 'investigation_status': 'Ongoing',
 'references': [{'date_accessed': '2023-10-04',
                 'source': 'Nikkei Inc. Disclosure'}],
 'response': {'communication_strategy': 'Public disclosure and individual '
                                        'contact with affected recipients',
              'containment_measures': ['Password resets',
                                       'Contacted affected recipients to '
                                       'delete fraudulent emails']},
 'title': 'Nikkei Cyberattack Targeting Microsoft 365 and Google Workspace '
          'Accounts',
 'type': ['Phishing', 'Unauthorized Access']}