dentsu
Company Details
Linkedin ID:
dentsu-aegis-network
Website:
Employees number:
17,322
Number of followers:
1,481,437
NAICS:
541613
Industry Type:
Homepage:
bit.ly
IP Addresses:
0
Company ID:
DEN_1986587
Scan Status:
In-progress
dentsu Company CyberSecurity Posture
bit.ly
We are dentsu. We team together to help brands predict and plan for disruptive future opportunities and create new paths to growth in the sustainable economy. We know people better than anyone else and we use those insights to connect brand, content, commerce and experience, underpinned by modern creativity. We are the network designed for what’s next.
dentsu A.I CyberSecurity Scoring
dentsu Risk Score (AI oriented)Between 800 and 849
dentsu
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dentsu Global Score (TPRM)XXXX
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dentsu Company CyberSecurity News & History
Past Incidents
4
Attack Types
2
Dentsu (via Merkle’s network)
Breach
Rankiteo Explanation
Attack with significant impact with internal employee data leaks
Description: Dentsu, a global advertising and media network, suffered a security breach within its subsidiary **Merkle’s network**, resulting in the theft of sensitive files. The compromised data included **personal and financial details** of **current and former employees**, as well as **some clients and suppliers**. Exposed information comprised **names, bank/payroll details, salaries, National Insurance numbers, and personal contact details**.The company detected **unusual network activity**, triggering an immediate response: systems were taken offline, incident response protocols were activated, and third-party cybersecurity firms alongside law enforcement were engaged. While Dentsu restored operations, the investigation remains ongoing. Affected individuals were notified and offered **credit/dark-web monitoring services** via Experian Identity Plus to mitigate risks like identity theft or financial fraud.The breach coincides with Dentsu’s strategic review, including potential divestments of its international creative and media divisions, raising concerns about operational stability. The incident underscores vulnerabilities in handling **highly sensitive employee and client data**, with potential long-term reputational and financial repercussions.
Dentsu
Breach
Rankiteo Explanation
Attack with significant impact with internal employee data leaks
Description: Dentsu, a global advertising and marketing agency, suffered a significant data breach affecting its CX agency, Merkle. The incident involved unauthorized access to files containing sensitive personal and financial data of **current and former employees**, including bank/payroll details, salaries, National Insurance numbers, and contact information. The breach also extended to **LNER (London North Eastern Railway) customer data**, exposing contact details and journey histories, though no payment or password data was compromised. The breach triggered a complaint to the UK’s **Information Commissioner’s Office (ICO)**, with affected ex-employees forming legal groups (one WhatsApp group exceeding 150 members) to pursue collective action. Dentsu acknowledged the leak exceeded legal reporting thresholds and offered affected individuals a year of **Experian Identity Plus** for monitoring. However, frustration persists over delayed notifications, unclear specifics of leaked data, and Dentsu’s retention of records beyond standard HMRC timelines (some ex-employees left over a decade ago). The ICO may impose fines (up to **£8.7M or 2% of global turnover**) if negligence is proven, separate from potential compensation claims.
Dentsu (Merkle)
Cyber Attack
Rankiteo Explanation
Attack with significant impact with internal employee data leaks
Description: Dentsu’s customer experience unit, **Merkle**, suffered a **cyberattack** resulting in the theft of **sensitive employee data**, including bank/payroll details, salaries, National Insurance numbers, and contact information for **current and former employees** (some dating back over a decade). The breach triggered legal action, with over **150 ex-employees** organizing via WhatsApp to pursue group litigation, alleging Dentsu’s failure to implement adequate security or comply with data retention policies. The UK’s **Information Commissioner’s Office (ICO)** is investigating, with potential fines up to **2% of global turnover** or multi-million-dollar penalties. While Dentsu engaged cybersecurity firms and offered credit/dark-web monitoring, affected individuals report **unclear communication** about exposed data, heightening fraud risks. The incident compounds Dentsu’s reputational and financial strain, coinciding with an unrelated **money-laundering probe** in India linked to a third-party acquisition (InDeed), though no direct connection to the Merkle breach was established.
Merkle (Dentsu’s US subsidiary)
Cyber Attack
Rankiteo Explanation
Attack with significant impact with customers data leaks
Description: Merkle, a US-based subsidiary of the Japanese multinational advertising giant Dentsu, suffered a cyberattack resulting in the exposure of sensitive data. The breach compromised files containing personal, payroll, and National Insurance details of current and former employees, as well as supplier and client data. The company took immediate action by shutting down certain systems to contain the attack and initiated an investigation with external cybersecurity experts. While the financial impact remains unclear, affected individuals are being notified and offered free dark web monitoring. The attack did not affect Dentsu’s systems in Japan, but the scale of the breach raises concerns given Merkle’s global workforce of over 16,000 employees and annual revenue of approximately $1.5 billion. No ransomware group has claimed responsibility, leaving the attack method unspecified beyond confirmation of data exfiltration.
dentsu Company Scoring based on AI Models
Cyber Incidents Likelihood 3 - 6 - 9 months
A.I Risk Score Likelihood 3 - 6 - 9 months
Underwriter Stats for dentsu
Incidents vs Advertising Services Industry Average (This Year)
No incidents recorded for dentsu in 2025.
Incidents vs All-Companies Average (This Year)
No incidents recorded for dentsu in 2025.
Incident Types dentsu vs Advertising Services Industry Avg (This Year)
No incidents recorded for dentsu in 2025.
Incident History — dentsu (X = Date, Y = Severity)
dentsu cyber incidents detection timeline including parent company and subsidiaries
dentsu Company Subsidiaries
We are dentsu. We team together to help brands predict and plan for disruptive future opportunities and create new paths to growth in the sustainable economy. We know people better than anyone else and we use those insights to connect brand, content, commerce and experience, underpinned by modern creativity. We are the network designed for what’s next.
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dentsu CyberSecurity News
November 11, 2025 03:12 PM
Dentsu leak compromised LNER customer data
Dentsu's data breach has compromised LNER'S customer data. Campaign reported in late October that former, current and “some clients” at...
November 11, 2025 02:38 PM
Digitas and Dentsu X notch gains as Initiative holds lead in November US rankings
iProspect and Hearts & Science join the agency table.. From Campaign US.
November 07, 2025 10:29 AM
Bank, payroll and National Insurance details stolen in Dentsu security incident
Dentsu says personal information from current and former employees has been taken during a cyber incident at its Merkle division.
November 06, 2025 08:00 AM
Cyber Compliance Specialist - South Africa - Johannesburg
A bachelor's degree in information technology, Cybersecurity, Computer Science, or related field. A minimum experience of 3-5 years in...
November 03, 2025 08:00 AM
MSP cybersecurity news digest, November 3, 2025
Qilin ransomware abuses Windows Subsystem for Linux to deploy Linux encryptors on Windows, Atroposia malware includes built-in vulnerability...
October 31, 2025 07:00 AM
Cybersecurity News: LinkedIn AI opt-out, NSA leadership candidates, Python foundation withdraws
As reported by Graham Cluley, the Microsoft-owned company professional networking site has “quietly announced” that as of this upcoming...
October 30, 2025 06:58 PM
Breach Roundup: Hackers Probe Canada's Critical Infrastructure
Every week, Information Security Media Group rounds up cybersecurity incidents and breaches around the world.
October 30, 2025 07:00 AM
Dentsu’s US subsidiary Merkle hit by cyberattack, staff and client data exposed
Dentsu said its U.S. unit Merkle was hit by a cyberattack exposing staff and client data, forcing some systems offline.
October 30, 2025 07:00 AM
Dentsu has Disclosed that its U.S.-based Subsidiary Merkle Suffers Cyberattack
Dentsu confirmed Merkle experienced a cyberattack, prompting immediate incident response measures and system shutdowns to contain the...
Frequently Asked Questions
Explore insights on cybersecurity incidents, risk posture, and Rankiteo's assessments.
dentsu CyberSecurity History Information
Official Website of dentsu
The official website of dentsu is https://bit.ly/3lDa6Ff.
dentsu’s AI-Generated Cybersecurity Score
According to Rankiteo, dentsu’s AI-generated cybersecurity score is 800, reflecting their Good security posture.
How many security badges does dentsu’ have ?
According to Rankiteo, dentsu currently holds 0 security badges, indicating that no recognized compliance certifications are currently verified for the organization.
Does dentsu have SOC 2 Type 1 certification ?
According to Rankiteo, dentsu is not certified under SOC 2 Type 1.
Does dentsu have SOC 2 Type 2 certification ?
According to Rankiteo, dentsu does not hold a SOC 2 Type 2 certification.
Does dentsu comply with GDPR ?
According to Rankiteo, dentsu is not listed as GDPR compliant.
Does dentsu have PCI DSS certification ?
According to Rankiteo, dentsu does not currently maintain PCI DSS compliance.
Does dentsu comply with HIPAA ?
According to Rankiteo, dentsu is not compliant with HIPAA regulations.
Does dentsu have ISO 27001 certification ?
According to Rankiteo,dentsu is not certified under ISO 27001, indicating the absence of a formally recognized information security management framework.
Industry Classification of dentsu
dentsu operates primarily in the Advertising Services industry.
Number of Employees at dentsu
dentsu employs approximately 17,322 people worldwide.
Subsidiaries Owned by dentsu
dentsu presently has no subsidiaries across any sectors.
dentsu’s LinkedIn Followers
dentsu’s official LinkedIn profile has approximately 1,481,437 followers.
NAICS Classification of dentsu
dentsu is classified under the NAICS code 541613, which corresponds to Marketing Consulting Services.
dentsu’s Presence on Crunchbase
No, dentsu does not have a profile on Crunchbase.
dentsu’s Presence on LinkedIn
Yes, dentsu maintains an official LinkedIn profile, which is actively utilized for branding and talent engagement, which can be accessed here: https://www.linkedin.com/company/dentsu-aegis-network.
Cybersecurity Incidents Involving dentsu
As of November 27, 2025, Rankiteo reports that dentsu has experienced 4 cybersecurity incidents.
Number of Peer and Competitor Companies
dentsu has an estimated 32,306 peer or competitor companies worldwide.
What types of cybersecurity incidents have occurred at dentsu ?
Incident Types: The types of cybersecurity incidents that have occurred include Breach and Cyber Attack.
How does dentsu detect and respond to cybersecurity incidents ?
Detection and Response: The company detects and responds to cybersecurity incidents through an incident response plan activated with yes (systems shut down, measures taken to minimize impact), and third party assistance with yes (external cybersecurity firm involved), and law enforcement notified with yes (relevant authorities in impacted countries notified), and containment measures with systems taken offline to mitigate attack, and recovery measures with systems restored after mitigation, and communication strategy with public disclosure, notification to affected individuals, offer of free dark web monitoring, and and third party assistance with cybersecurity firm (unnamed), third party assistance with experian identity plus (for monitoring services), and and containment measures with systems taken offline, containment measures with incident response protocols initiated, and recovery measures with systems brought back online, and communication strategy with internal email to employees, communication strategy with public statement, communication strategy with notification process for affected parties, and and third party assistance with cybersecurity firm (unnamed), and and remediation measures with offered experian identity plus (1-year subscription for credit/dark-web monitoring), and communication strategy with initial notification to affected individuals (27 oct 2023), communication strategy with encouraged monitoring of financial statements, communication strategy with no further updates provided, and enhanced monitoring with fraud monitoring recommended for affected individuals, and incident response plan activated with yes (cybersecurity firm engaged), and third party assistance with yes (external cybersecurity firm), and law enforcement notified with yes (uk and india), and remediation measures with credit monitoring, remediation measures with dark web monitoring for affected individuals, and communication strategy with initial notification to staff (oct 2025), communication strategy with limited follow-up per employee reports..
Incident Details
Can you provide details on each incident ?
Title: Dentsu’s US subsidiary Merkle hit by cyberattack, staff and client data exposed
Description: Japanese multinational advertising and public relations company Dentsu announced that its U.S.-based subsidiary Merkle suffered a cyberattack exposing staff and client data. The company took certain systems offline to mitigate the attack and is investigating with external cybersecurity support. Hackers stole files containing supplier, client, and employee data, including personal, payroll, and National Insurance details. Affected individuals are being notified and offered free dark web monitoring. The financial impact is currently unknown.
Date Detected: 2025-10-30
Date Publicly Disclosed: 2025-10-30
Type: Cyberattack (Data Breach)
Title: Data Breach at Dentsu's Merkle Network Affecting Employees, Clients, and Suppliers
Description: Former and current staff at Dentsu and some clients had their information taken following a security incident within Merkle’s network. Files containing names, bank and payroll details, salary, National Insurance numbers, and personal contact details were exfiltrated. Dentsu has engaged third-party cybersecurity firms, notified law enforcement, and offered affected individuals credit and dark-web monitoring services via Experian Identity Plus. The investigation remains ongoing, but notifications have begun in compliance with applicable laws.
Type: data breach
Title: Dentsu Data Breach Affecting Former Employees and LNER Customers
Description: Dentsu reported a data breach where files containing personal and financial details of former employees (including bank/payroll details, salary, National Insurance numbers, and contact details) were exfiltrated from Merkle’s network. The breach also impacted LNER customer data, including contact details and journey information. The ICO is investigating, and affected individuals are considering legal action. Dentsu offered credit monitoring services and notified law enforcement.
Date Publicly Disclosed: 2023-10-27
Type: Data Breach
Title: Dentsu's Merkle Data Breach and Suumaya Money Laundering Investigation
Description: A cyberattack on Dentsu's Merkle unit led to the theft of sensitive employee and client information, sparking legal action and regulatory scrutiny. Concurrently, Dentsu's Indian business is entangled in a ₹137 crore money-laundering probe linked to the Suumaya Group, involving fake contracts and shell companies. The UK ICO is reviewing the data breach, while India's Enforcement Directorate investigates financial fraud.
Date Publicly Disclosed: 2025-10-01
Type: Data Breach
Motivation: Financial GainData Theft
What are the most common types of attacks the company has faced ?
Common Attack Types: The most common types of attacks the company has faced is Breach.
Impact of the Incidents
What was the impact of each incident ?
Incident : Cyberattack (Data Breach) MER3332133103025
Data Compromised: Supplier data, Client data, Employee data (personal details, payroll, national insurance numbers, bank details, salary, contact details)
Systems Affected: Certain network systems (taken offline during mitigation)
Downtime: Partial (some systems shut down and later restored)
Operational Impact: Systems taken offline to mitigate breach; investigation ongoing
Brand Reputation Impact: Potential reputational damage due to exposure of sensitive data
Identity Theft Risk: High (personal and financial data exposed)
Payment Information Risk: High (bank and payroll details compromised)
Incident : data breach DEN1492114110225
Data Compromised: Names, Bank details, Payroll details, Salary information, National insurance numbers, Personal contact details
Systems Affected: portion of Merkle’s network
Downtime: temporary (some systems taken offline as precaution)
Operational Impact: minimal (fully operational after containment)
Brand Reputation Impact: potential (ongoing investigation amid speculation about Dentsu's future)
Identity Theft Risk: high (bank, payroll, and PII exposed)
Payment Information Risk: high (bank details compromised)
Incident : Data Breach DEN0962609112125
Data Compromised: Bank/payroll details, Salary information, National insurance numbers, Personal contact details, Lner customer contact details, Lner journey information
Systems Affected: Merkle’s (Dentsu’s CX agency) network
Customer Complaints: ['Collective legal action being considered by former employees', 'Frustration over lack of follow-up communication', 'Complaints about prolonged data retention (10+ years)']
Brand Reputation Impact: Potential reputational damage due to legal action and regulatory scrutinyNegative media coverage
Legal Liabilities: Potential ICO fines (up to £8.7M or 2% of global turnover)Group action claims by former employeesViolation of UK GDPR and Data Protection Act 2018 (excessive data retention)
Identity Theft Risk: ['High (due to exposure of National Insurance numbers, bank details, and personal contact information)']
Payment Information Risk: ['Exposed for former employees (bank/payroll details)', 'Not affected for LNER customers']
Incident : Data Breach MER4741147112625
Data Compromised: Bank details, Payroll details, Salaries, National insurance numbers, Contact information
Systems Affected: Merkle’s network
Customer Complaints: High (150+ ex-employees in WhatsApp group pursuing legal action)
Brand Reputation Impact: Significant (employee frustration, legal threats, regulatory scrutiny)
Legal Liabilities: Potential ICO fines (up to 2% of global turnover)Employee compensation claimsMoney laundering investigation
Identity Theft Risk: High (exfiltrated PII, dark web exposure risk)
Payment Information Risk: High (bank and payroll details compromised)
What types of data are most commonly compromised in incidents ?
Commonly Compromised Data Types: The types of data most commonly compromised in incidents are Personal Details, Payroll Data, National Insurance Numbers, Bank Details, Salary Information, Contact Details, Supplier Data, Client Data, , Personal Identifiable Information (Pii), Financial Data, Employment Records, , Personal Identifiable Information (Pii), Financial Data, Employment Records, Customer Contact Details, Journey Information, , Personally Identifiable Information (Pii), Financial Data and .
Which entities were affected by each incident ?
Incident : Cyberattack (Data Breach) MER3332133103025
Entity Name: Merkle, Inc.
Entity Type: Subsidiary
Industry: Marketing and Customer Experience Management (CXM)
Location: United States
Size: 16,000+ employees globally
Incident : Cyberattack (Data Breach) MER3332133103025
Entity Name: Dentsu Group
Entity Type: Parent Company
Industry: Advertising and Public Relations
Location: Japan (global operations)
Size: 67,667 employees (as of December 31, 2024)
Incident : data breach DEN1492114110225
Entity Name: Dentsu (via Merkle network)
Entity Type: advertising and marketing agency
Industry: media and communications
Customers Affected: some clients, suppliers, and current/former employees
Incident : Data Breach DEN0962609112125
Entity Name: Dentsu (including Merkle CX agency)
Entity Type: Advertising/Media Conglomerate
Industry: Marketing & Advertising
Location: United KingdomJapan (HQ)
Customers Affected: Current/former employees (150+ in one WhatsApp group), Clients, Suppliers
Incident : Data Breach DEN0962609112125
Entity Name: London North Eastern Railway (LNER)
Entity Type: Train Operator
Industry: Transportation
Location: United Kingdom
Customers Affected: Unknown (contact details and journey information exposed)
Incident : Data Breach MER4741147112625
Entity Name: Dentsu Group (Merkle unit)
Entity Type: Advertising and Marketing Agency
Industry: Media & Communications
Location: UK (global operations)
Customers Affected: Current and former employees (some left >10 years ago)
Incident : Data Breach MER4741147112625
Entity Name: Dentsu India
Entity Type: Subsidiary
Industry: Media & Communications
Location: India
Incident : Data Breach MER4741147112625
Entity Name: Suumaya Group
Entity Type: Agro-trading and Welfare Programme Contractor
Industry: Agriculture/Government Contracts
Location: India (Haryana, Delhi)
Response to the Incidents
What measures were taken in response to each incident ?
Incident : Cyberattack (Data Breach) MER3332133103025
Incident Response Plan Activated: Yes (systems shut down, measures taken to minimize impact)
Third Party Assistance: Yes (external cybersecurity firm involved)
Law Enforcement Notified: Yes (relevant authorities in impacted countries notified)
Containment Measures: Systems taken offline to mitigate attack
Recovery Measures: Systems restored after mitigation
Communication Strategy: Public disclosure, notification to affected individuals, offer of free dark web monitoring
Incident : data breach DEN1492114110225
Incident Response Plan Activated: True
Third Party Assistance: Cybersecurity Firm (Unnamed), Experian Identity Plus (For Monitoring Services).
Containment Measures: systems taken offlineincident response protocols initiated
Recovery Measures: systems brought back online
Communication Strategy: internal email to employeespublic statementnotification process for affected parties
Incident : Data Breach DEN0962609112125
Incident Response Plan Activated: True
Third Party Assistance: Cybersecurity Firm (Unnamed).
Remediation Measures: Offered Experian Identity Plus (1-year subscription for credit/dark-web monitoring)
Communication Strategy: Initial notification to affected individuals (27 Oct 2023)Encouraged monitoring of financial statementsNo further updates provided
Enhanced Monitoring: Fraud monitoring recommended for affected individuals
Incident : Data Breach MER4741147112625
Incident Response Plan Activated: Yes (cybersecurity firm engaged)
Third Party Assistance: Yes (external cybersecurity firm)
Law Enforcement Notified: Yes (UK and India)
Remediation Measures: Credit monitoringDark web monitoring for affected individuals
Communication Strategy: Initial notification to staff (Oct 2025)Limited follow-up per employee reports
What is the company's incident response plan?
Incident Response Plan: The company's incident response plan is described as Yes (systems shut down, measures taken to minimize impact), , , Yes (cybersecurity firm engaged).
How does the company involve third-party assistance in incident response ?
Third-Party Assistance: The company involves third-party assistance in incident response through Yes (external cybersecurity firm involved), cybersecurity firm (unnamed), Experian Identity Plus (for monitoring services), , Cybersecurity firm (unnamed), , Yes (external cybersecurity firm).
Data Breach Information
What type of data was compromised in each breach ?
Incident : Cyberattack (Data Breach) MER3332133103025
Type of Data Compromised: Personal details, Payroll data, National insurance numbers, Bank details, Salary information, Contact details, Supplier data, Client data
Sensitivity of Data: High (includes financial and personally identifiable information)
Data Exfiltration: Yes (files taken from Merkle’s network)
Personally Identifiable Information: Yes (names, contact details, National Insurance numbers, bank/payroll details)
Incident : data breach DEN1492114110225
Type of Data Compromised: Personal identifiable information (pii), Financial data, Employment records
Sensitivity of Data: high (includes bank details, National Insurance numbers, and salary information)
Personally Identifiable Information: namesNational Insurance numberspersonal contact details
Incident : Data Breach DEN0962609112125
Type of Data Compromised: Personal identifiable information (pii), Financial data, Employment records, Customer contact details, Journey information
Sensitivity of Data: High (includes National Insurance numbers, bank details, salaries)
Personally Identifiable Information: NamesNational Insurance numbersBank/payroll detailsSalariesPersonal contact details (email/phone/address)
Incident : Data Breach MER4741147112625
Type of Data Compromised: Personally identifiable information (pii), Financial data
Sensitivity of Data: High (bank details, National Insurance numbers)
Data Exfiltration: Confirmed ('certain files' stolen)
Personally Identifiable Information: NamesContact detailsNational Insurance numbersSalariesBank detailsPayroll details
What measures does the company take to prevent data exfiltration ?
Prevention of Data Exfiltration: The company takes the following measures to prevent data exfiltration: Offered Experian Identity Plus (1-year subscription for credit/dark-web monitoring), , Credit monitoring, Dark web monitoring for affected individuals, .
How does the company handle incidents involving personally identifiable information (PII) ?
Handling of PII Incidents: The company handles incidents involving personally identifiable information (PII) through by systems taken offline to mitigate attack, systems taken offline, incident response protocols initiated and .
Ransomware Information
Was ransomware involved in any of the incidents ?
Incident : Cyberattack (Data Breach) MER3332133103025
Data Exfiltration: Yes (files stolen, but no ransomware claim reported)
Incident : data breach DEN1492114110225
Data Exfiltration: True
Incident : Data Breach DEN0962609112125
Data Exfiltration: True
Incident : Data Breach MER4741147112625
Data Exfiltration: Yes
How does the company recover data encrypted by ransomware ?
Data Recovery from Ransomware: The company recovers data encrypted by ransomware through Systems restored after mitigation, systems brought back online, .
Regulatory Compliance
Were there any regulatory violations and fines imposed for each incident ?
Incident : Cyberattack (Data Breach) MER3332133103025
Regulatory Notifications: Relevant authorities in impacted countries notified
Incident : data breach DEN1492114110225
Regulatory Notifications: ongoing (notifications begun in accordance with applicable law)
Incident : Data Breach DEN0962609112125
Regulations Violated: UK GDPR, Data Protection Act 2018 (excessive data retention beyond 7 years),
Legal Actions: ICO investigation ongoing, Potential group action claims by former employees,
Regulatory Notifications: Reported to ICO (scale exceeded legal threshold)Law enforcement notified
Incident : Data Breach MER4741147112625
Regulations Violated: UK GDPR (potential), India’s Prevention of Money Laundering Act (PMLA),
Legal Actions: UK ICO review (ongoing), ED investigation (ongoing), Employee group litigation (potential),
Regulatory Notifications: UK ICO complaint filedED searches conducted (Dentsu India offices)
How does the company ensure compliance with regulatory requirements ?
Ensuring Regulatory Compliance: The company ensures compliance with regulatory requirements through ICO investigation ongoing, Potential group action claims by former employees, , UK ICO review (ongoing), ED investigation (ongoing), Employee group litigation (potential), .
Lessons Learned and Recommendations
What recommendations were made to prevent future incidents ?
Incident : data breach DEN1492114110225
Recommendations: monitor financial statements, use credit/dark-web monitoring services (e.g., Experian Identity Plus)monitor financial statements, use credit/dark-web monitoring services (e.g., Experian Identity Plus)
Incident : Data Breach DEN0962609112125
Recommendations: Improve data retention policies to comply with UK GDPR (max 7 years for HMRC-related records), Enhance transparency in post-breach communication (e.g., clarify which specific data was exposed per individual), Proactively engage with affected parties to mitigate legal risks, Review third-party supplier security (LNER breach linked to Dentsu’s systems)Improve data retention policies to comply with UK GDPR (max 7 years for HMRC-related records), Enhance transparency in post-breach communication (e.g., clarify which specific data was exposed per individual), Proactively engage with affected parties to mitigate legal risks, Review third-party supplier security (LNER breach linked to Dentsu’s systems)Improve data retention policies to comply with UK GDPR (max 7 years for HMRC-related records), Enhance transparency in post-breach communication (e.g., clarify which specific data was exposed per individual), Proactively engage with affected parties to mitigate legal risks, Review third-party supplier security (LNER breach linked to Dentsu’s systems)Improve data retention policies to comply with UK GDPR (max 7 years for HMRC-related records), Enhance transparency in post-breach communication (e.g., clarify which specific data was exposed per individual), Proactively engage with affected parties to mitigate legal risks, Review third-party supplier security (LNER breach linked to Dentsu’s systems)
References
Where can I find more information about each incident ?
Incident : Cyberattack (Data Breach) MER3332133103025
Source: SecurityAffairs
URL: https://securityaffairs.com
Date Accessed: 2025-10-30
Incident : data breach DEN1492114110225
Source: Campaign (marketing industry publication)
Incident : Data Breach DEN0962609112125
Source: Campaign UK
Incident : Data Breach DEN0962609112125
Source: Information Commissioner’s Office (ICO) Statement
Incident : Data Breach DEN0962609112125
Source: Withers Law Firm (Jo Sanders, Data/Information Disputes Partner)
Incident : Data Breach MER4741147112625
Source: Financial Times / Media Report
Date Accessed: 2025-11-26
Incident : Data Breach MER4741147112625
Source: Enforcement Directorate (ED) Press Release
Date Accessed: 2025-11-26
Where can stakeholders find additional resources on cybersecurity best practices ?
Additional Resources: Stakeholders can find additional resources on cybersecurity best practices at and Source: SecurityAffairsUrl: https://securityaffairs.comDate Accessed: 2025-10-30, and Source: Campaign (marketing industry publication), and Source: Campaign UK, and Source: Information Commissioner’s Office (ICO) Statement, and Source: Withers Law Firm (Jo Sanders, Data/Information Disputes Partner), and Source: Financial Times / Media ReportDate Accessed: 2025-11-26, and Source: Enforcement Directorate (ED) Press ReleaseDate Accessed: 2025-11-26.
Investigation Status
What is the current status of the investigation for each incident ?
Incident : Cyberattack (Data Breach) MER3332133103025
Investigation Status: Ongoing (external cybersecurity firm involved)
Incident : data breach DEN1492114110225
Investigation Status: ongoing
Incident : Data Breach DEN0962609112125
Investigation Status: Ongoing (ICO inquiry and internal investigation with cybersecurity firm)
Incident : Data Breach MER4741147112625
Investigation Status: ['Ongoing (UK ICO)', 'Ongoing (ED India)', 'Employee-led legal preparations']
How does the company communicate the status of incident investigations to stakeholders ?
Communication of Investigation Status: The company communicates the status of incident investigations to stakeholders through Public disclosure, notification to affected individuals, offer of free dark web monitoring, Internal Email To Employees, Public Statement, Notification Process For Affected Parties, Initial Notification To Affected Individuals (27 Oct 2023), Encouraged Monitoring Of Financial Statements, No Further Updates Provided, Initial Notification To Staff (Oct 2025) and Limited Follow-Up Per Employee Reports.
Stakeholder and Customer Advisories
Were there any advisories issued to stakeholders or customers for each incident ?
Incident : Cyberattack (Data Breach) MER3332133103025
Stakeholder Advisories: Affected individuals notified; free dark web monitoring offered
Incident : data breach DEN1492114110225
Stakeholder Advisories: Internal Email To Employees, Public Statement.
Customer Advisories: encouraged to monitor financial statementsoffered Experian Identity Plus subscription
Incident : Data Breach DEN0962609112125
Customer Advisories: Dentsu: Monitor financial statements; offered Experian Identity Plus.LNER: No bank/payment card/password data affected; investigation underway.
Incident : Data Breach MER4741147112625
Customer Advisories: Credit monitoring offered to affected employees
What advisories does the company provide to stakeholders and customers following an incident ?
Advisories Provided: The company provides the following advisories to stakeholders and customers following an incident: were Affected individuals notified; free dark web monitoring offered, Internal Email To Employees, Public Statement, Encouraged To Monitor Financial Statements, Offered Experian Identity Plus Subscription, , Dentsu: Monitor Financial Statements; Offered Experian Identity Plus., Lner: No Bank/Payment Card/Password Data Affected; Investigation Underway., , Credit Monitoring Offered To Affected Employees and .
Initial Access Broker
How did the initial access broker gain entry for each incident ?
Incident : data breach DEN1492114110225
High Value Targets: Employee Data, Client/Supplier Data,
Data Sold on Dark Web: Employee Data, Client/Supplier Data,
Incident : Data Breach DEN0962609112125
High Value Targets: Employee Pii/Financial Data, Client/Supplier Data,
Data Sold on Dark Web: Employee Pii/Financial Data, Client/Supplier Data,
Incident : Data Breach MER4741147112625
High Value Targets: Employee Pii, Client Data,
Data Sold on Dark Web: Employee Pii, Client Data,
Post-Incident Analysis
What were the root causes and corrective actions taken for each incident ?
Incident : Data Breach DEN0962609112125
Root Causes: Inadequate Data Retention Policies (Retained Data For 10+ Years Beyond Legal Limits), Potential Third-Party Security Vulnerabilities (Merkle’S Network),
What is the company's process for conducting post-incident analysis ?
Post-Incident Analysis Process: The company's process for conducting post-incident analysis is described as Cybersecurity Firm (Unnamed), Experian Identity Plus (For Monitoring Services), , Cybersecurity Firm (Unnamed), , Fraud Monitoring Recommended For Affected Individuals, , .
Additional Questions
Incident Details
What was the most recent incident detected ?
Most Recent Incident Detected: The most recent incident detected was on 2025-10-30.
What was the most recent incident publicly disclosed ?
Most Recent Incident Publicly Disclosed: The most recent incident publicly disclosed was on 2025-10-01.
Impact of the Incidents
What was the most significant data compromised in an incident ?
Most Significant Data Compromised: The most significant data compromised in an incident were Supplier data, Client data, Employee data (personal details, payroll, National Insurance numbers, bank details, salary, contact details), , names, bank details, payroll details, salary information, National Insurance numbers, personal contact details, , Bank/payroll details, Salary information, National Insurance numbers, Personal contact details, LNER customer contact details, LNER journey information, , Bank details, Payroll details, Salaries, National Insurance numbers, Contact information and .
What was the most significant system affected in an incident ?
Most Significant System Affected: The most significant system affected in an incident was portion of Merkle’s network and Merkle’s (Dentsu’s CX agency) network and Merkle’s network.
Response to the Incidents
What third-party assistance was involved in the most recent incident ?
Third-Party Assistance in Most Recent Incident: The third-party assistance involved in the most recent incident was cybersecurity firm (unnamed), experian identity plus (for monitoring services), , cybersecurity firm (unnamed), , .
What containment measures were taken in the most recent incident ?
Containment Measures in Most Recent Incident: The containment measures taken in the most recent incident were Systems taken offline to mitigate attack and systems taken offlineincident response protocols initiated.
Data Breach Information
What was the most sensitive data compromised in a breach ?
Most Sensitive Data Compromised: The most sensitive data compromised in a breach were Bank/payroll details, LNER journey information, Payroll details, bank details, Bank details, Client data, Supplier data, personal contact details, Contact information, payroll details, LNER customer contact details, Salaries, names, Employee data (personal details, payroll, National Insurance numbers, bank details, salary, contact details), Personal contact details, salary information, Salary information and National Insurance numbers.
Regulatory Compliance
What was the most significant legal action taken for a regulatory violation ?
Most Significant Legal Action: The most significant legal action taken for a regulatory violation was ICO investigation ongoing, Potential group action claims by former employees, , UK ICO review (ongoing), ED investigation (ongoing), Employee group litigation (potential), .
Lessons Learned and Recommendations
What was the most significant recommendation implemented to improve cybersecurity ?
Most Significant Recommendation Implemented: The most significant recommendation implemented to improve cybersecurity was monitor financial statements, Proactively engage with affected parties to mitigate legal risks, Review third-party supplier security (LNER breach linked to Dentsu’s systems), Improve data retention policies to comply with UK GDPR (max 7 years for HMRC-related records), use credit/dark-web monitoring services (e.g., Experian Identity Plus), Enhance transparency in post-breach communication (e.g. and clarify which specific data was exposed per individual).
References
What is the most recent source of information about an incident ?
Most Recent Source: The most recent source of information about an incident are SecurityAffairs, Enforcement Directorate (ED) Press Release, Financial Times / Media Report, Information Commissioner’s Office (ICO) Statement, Campaign UK, Campaign (marketing industry publication), Withers Law Firm (Jo Sanders and Data/Information Disputes Partner).
What is the most recent URL for additional resources on cybersecurity best practices ?
Most Recent URL for Additional Resources: The most recent URL for additional resources on cybersecurity best practices is https://securityaffairs.com .
Investigation Status
What is the current status of the most recent investigation ?
Current Status of Most Recent Investigation: The current status of the most recent investigation is Ongoing (external cybersecurity firm involved).
Stakeholder and Customer Advisories
What was the most recent stakeholder advisory issued ?
Most Recent Stakeholder Advisory: The most recent stakeholder advisory issued was Affected individuals notified; free dark web monitoring offered, internal email to employees, public statement, .
What was the most recent customer advisory issued ?
Most Recent Customer Advisory: The most recent customer advisory issued were an encouraged to monitor financial statementsoffered Experian Identity Plus subscription, Dentsu: Monitor financial statements; offered Experian Identity Plus.LNER: No bank/payment card/password data affected; investigation underway. and Credit monitoring offered to affected employees.
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Latest Global CVEs (Not Company-Specific)
Description
Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to versions 19.2.16, 20.3.14, and 21.0.1, there is a XSRF token leakage via protocol-relative URLs in angular HTTP clients. The vulnerability is a Credential Leak by App Logic that leads to the unauthorized disclosure of the Cross-Site Request Forgery (XSRF) token to an attacker-controlled domain. Angular's HttpClient has a built-in XSRF protection mechanism that works by checking if a request URL starts with a protocol (http:// or https://) to determine if it is cross-origin. If the URL starts with protocol-relative URL (//), it is incorrectly treated as a same-origin request, and the XSRF token is automatically added to the X-XSRF-TOKEN header. This issue has been patched in versions 19.2.16, 20.3.14, and 21.0.1. A workaround for this issue involves avoiding using protocol-relative URLs (URLs starting with //) in HttpClient requests. All backend communication URLs should be hardcoded as relative paths (starting with a single /) or fully qualified, trusted absolute URLs.
Risk Information
cvss4
Base: 7.7
Severity: LOW
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
References
- https://github.com/angular/angular/commit/0276479e7d0e280e0f8d26fa567d3b7aa97a516f
- https://github.com/angular/angular/commit/05fe6686a97fa0bcd3cf157805b3612033f975bc
- https://github.com/angular/angular/commit/3240d856d942727372a705252f7c8c115394a41e
- https://github.com/angular/angular/releases/tag/19.2.16
- https://github.com/angular/angular/releases/tag/20.3.14
- https://github.com/angular/angular/releases/tag/21.0.1
- https://github.com/angular/angular/security/advisories/GHSA-58c5-g7wp-6w37
Description
Forge (also called `node-forge`) is a native implementation of Transport Layer Security in JavaScript. An Uncontrolled Recursion vulnerability in node-forge versions 1.3.1 and below enables remote, unauthenticated attackers to craft deep ASN.1 structures that trigger unbounded recursive parsing. This leads to a Denial-of-Service (DoS) via stack exhaustion when parsing untrusted DER inputs. This issue has been patched in version 1.3.2.
Risk Information
cvss4
Base: 8.7
Severity: LOW
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Description
Forge (also called `node-forge`) is a native implementation of Transport Layer Security in JavaScript. An Integer Overflow vulnerability in node-forge versions 1.3.1 and below enables remote, unauthenticated attackers to craft ASN.1 structures containing OIDs with oversized arcs. These arcs may be decoded as smaller, trusted OIDs due to 32-bit bitwise truncation, enabling the bypass of downstream OID-based security decisions. This issue has been patched in version 1.3.2.
Risk Information
cvss4
Base: 6.3
Severity: LOW
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Description
Suricata is a network IDS, IPS and NSM engine developed by the OISF (Open Information Security Foundation) and the Suricata community. Prior to versions 7.0.13 and 8.0.2, working with large buffers in Lua scripts can lead to a stack overflow. Users of Lua rules and output scripts may be affected when working with large buffers. This includes a rule passing a large buffer to a Lua script. This issue has been patched in versions 7.0.13 and 8.0.2. A workaround for this issue involves disabling Lua rules and output scripts, or making sure limits, such as stream.depth.reassembly and HTTP response body limits (response-body-limit), are set to less than half the stack size.
Risk Information
cvss3
Base: 7.5
Severity: LOW
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Description
Suricata is a network IDS, IPS and NSM engine developed by the OISF (Open Information Security Foundation) and the Suricata community. In versions from 8.0.0 to before 8.0.2, a NULL dereference can occur when the entropy keyword is used in conjunction with base64_data. This issue has been patched in version 8.0.2. A workaround involves disabling rules that use entropy in conjunction with base64_data.
Risk Information
cvss3
Base: 7.5
Severity: LOW
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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Incident
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Digital Assets
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Network Security
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SBOM (Software Bill of Materials)
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CMDB (Configuration Management Database)
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Threat Intelligence
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