Company Details
dentsu
17,547
1,639,223
541613
dentsu.com
159
DEN_1102532
Completed

dentsu Company CyberSecurity Posture
dentsu.comWe 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.
Company Details
dentsu
17,547
1,639,223
541613
dentsu.com
159
DEN_1102532
Completed
Between 650 and 699

dentsu Global Score (TPRM)XXXX

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.
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 has 119.78% more incidents than the average of same-industry companies with at least one recorded incident.
dentsu has 212.5% more incidents than the average of all companies with at least one recorded incident.
dentsu reported 2 incidents this year: 0 cyber attacks, 0 ransomware, 0 vulnerabilities, 2 data breaches, compared to industry peers with at least 1 incident.
dentsu cyber incidents detection timeline including parent company and 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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Every week, Information Security Media Group rounds up cybersecurity incidents and breaches around the world.
Dentsu said its U.S. unit Merkle was hit by a cyberattack exposing staff and client data, forcing some systems offline.
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Explore insights on cybersecurity incidents, risk posture, and Rankiteo's assessments.
The official website of dentsu is https://bit.ly/3lDa6Ff.
According to Rankiteo, dentsu’s AI-generated cybersecurity score is 665, reflecting their Weak security posture.
According to Rankiteo, dentsu currently holds 0 security badges, indicating that no recognized compliance certifications are currently verified for the organization.
According to Rankiteo, dentsu is not certified under SOC 2 Type 1.
According to Rankiteo, dentsu does not hold a SOC 2 Type 2 certification.
According to Rankiteo, dentsu is not listed as GDPR compliant.
According to Rankiteo, dentsu does not currently maintain PCI DSS compliance.
According to Rankiteo, dentsu is not compliant with HIPAA regulations.
According to Rankiteo,dentsu is not certified under ISO 27001, indicating the absence of a formally recognized information security management framework.
dentsu operates primarily in the Advertising Services industry.
dentsu employs approximately 17,547 people worldwide.
dentsu presently has no subsidiaries across any sectors.
dentsu’s official LinkedIn profile has approximately 1,639,223 followers.
dentsu is classified under the NAICS code 541613, which corresponds to Marketing Consulting Services.
No, dentsu does not have a profile on Crunchbase.
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.
As of November 30, 2025, Rankiteo reports that dentsu has experienced 2 cybersecurity incidents.
dentsu has an estimated 32,350 peer or competitor companies worldwide.
Incident Types: The types of cybersecurity incidents that have occurred include Breach.
Detection and Response: The company detects and responds to cybersecurity incidents through an 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..
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
Common Attack Types: The most common types of attacks the company has faced is Breach.

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)

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']
Commonly Compromised Data Types: The types of data most commonly compromised in incidents are Personal Identifiable Information (Pii), Financial Data, Employment Records, , Personal Identifiable Information (Pii), Financial Data, Employment Records, Customer Contact Details, Journey Information and .

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

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

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 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 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
Third-Party Assistance: The company involves third-party assistance in incident response through cybersecurity firm (unnamed), Experian Identity Plus (for monitoring services), , Cybersecurity firm (unnamed), .

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

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)
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), .
Handling of PII Incidents: The company handles incidents involving personally identifiable information (PII) through by systems taken offline, incident response protocols initiated and .

Data Exfiltration: True

Data Exfiltration: True
Data Recovery from Ransomware: The company recovers data encrypted by ransomware through systems brought back online, .

Regulatory Notifications: ongoing (notifications begun in accordance with applicable law)

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
Ensuring Regulatory Compliance: The company ensures compliance with regulatory requirements through ICO investigation ongoing, Potential group action claims by former employees, .

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)

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)

Source: Campaign (marketing industry publication)

Source: Campaign UK

Source: Information Commissioner’s Office (ICO) Statement

Source: Withers Law Firm (Jo Sanders, Data/Information Disputes Partner)
Additional Resources: Stakeholders can find additional resources on cybersecurity best practices at 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).

Investigation Status: ongoing

Investigation Status: Ongoing (ICO inquiry and internal investigation with cybersecurity firm)
Communication of Investigation Status: The company communicates the status of incident investigations to stakeholders through Internal Email To Employees, Public Statement, Notification Process For Affected Parties, Initial Notification To Affected Individuals (27 Oct 2023), Encouraged Monitoring Of Financial Statements and No Further Updates Provided.

Stakeholder Advisories: Internal Email To Employees, Public Statement.
Customer Advisories: encouraged to monitor financial statementsoffered Experian Identity Plus subscription

Customer Advisories: Dentsu: Monitor financial statements; offered Experian Identity Plus.LNER: No bank/payment card/password data affected; investigation underway.
Advisories Provided: The company provides the following advisories to stakeholders and customers following an incident: were 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. and .

High Value Targets: Employee Data, Client/Supplier Data,
Data Sold on Dark Web: Employee Data, Client/Supplier Data,

High Value Targets: Employee Pii/Financial Data, Client/Supplier Data,
Data Sold on Dark Web: Employee Pii/Financial Data, Client/Supplier Data,

Root Causes: Inadequate Data Retention Policies (Retained Data For 10+ Years Beyond Legal Limits), Potential Third-Party Security Vulnerabilities (Merkle’S Network),
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, .
Most Recent Incident Publicly Disclosed: The most recent incident publicly disclosed was on 2023-10-27.
Most Significant Data Compromised: The most significant data compromised in an incident were 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 and .
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.
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), .
Containment Measures in Most Recent Incident: The containment measures taken in the most recent incident was systems taken offlineincident response protocols initiated.
Most Sensitive Data Compromised: The most sensitive data compromised in a breach were Bank/payroll details, personal contact details, names, payroll details, LNER customer contact details, LNER journey information, National Insurance numbers, Salary information, Personal contact details, salary information and bank details.
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, .
Most Significant Recommendation Implemented: The most significant recommendation implemented to improve cybersecurity was 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., clarify which specific data was exposed per individual), monitor financial statements, Review third-party supplier security (LNER breach linked to Dentsu’s systems) and Proactively engage with affected parties to mitigate legal risks.
Most Recent Source: The most recent source of information about an incident are Withers Law Firm (Jo Sanders, Data/Information Disputes Partner), Campaign (marketing industry publication), Campaign UK and Information Commissioner’s Office (ICO) Statement.
Current Status of Most Recent Investigation: The current status of the most recent investigation is ongoing.
Most Recent Stakeholder Advisory: The most recent stakeholder advisory issued was internal email to employees, public statement, .
Most Recent Customer Advisory: The most recent customer advisory issued were an encouraged to monitor financial statementsoffered Experian Identity Plus subscription and Dentsu: Monitor financial statements; offered Experian Identity Plus.LNER: No bank/payment card/password data affected; investigation underway.
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A vulnerability was determined in motogadget mo.lock Ignition Lock up to 20251125. Affected by this vulnerability is an unknown functionality of the component NFC Handler. Executing manipulation can lead to use of hard-coded cryptographic key . The physical device can be targeted for the attack. A high complexity level is associated with this attack. The exploitation appears to be difficult. The vendor was contacted early about this disclosure but did not respond in any way.
OrangeHRM is a comprehensive human resource management (HRM) system. From version 5.0 to 5.7, the interview attachment retrieval endpoint in the Recruitment module serves files based solely on an authenticated session and user-supplied identifiers, without verifying whether the requester has permission to access the associated interview record. Because the server does not perform any recruitment-level authorization checks, an ESS-level user with no access to recruitment workflows can directly request interview attachment URLs and receive the corresponding files. This exposes confidential interview documents—including candidate CVs, evaluations, and supporting files—to unauthorized users. The issue arises from relying on predictable object identifiers and session presence rather than validating the user’s association with the relevant recruitment process. This issue has been patched in version 5.8.
OrangeHRM is a comprehensive human resource management (HRM) system. From version 5.0 to 5.7, the application’s recruitment attachment retrieval endpoint does not enforce the required authorization checks before serving candidate files. Even users restricted to ESS-level access, who have no permission to view the Recruitment module, can directly access candidate attachment URLs. When an authenticated request is made to the attachment endpoint, the system validates the session but does not confirm that the requesting user has the necessary recruitment permissions. As a result, any authenticated user can download CVs and other uploaded documents for arbitrary candidates by issuing direct requests to the attachment endpoint, leading to unauthorized exposure of sensitive applicant data. This issue has been patched in version 5.8.
OrangeHRM is a comprehensive human resource management (HRM) system. From version 5.0 to 5.7, the application does not invalidate existing sessions when a user is disabled or when a password change occurs, allowing active session cookies to remain valid indefinitely. As a result, a disabled user, or an attacker using a compromised account, can continue to access protected pages and perform operations as long as a prior session remains active. Because the server performs no session revocation or session-store cleanup during these critical state changes, disabling an account or updating credentials has no effect on already-established sessions. This makes administrative disable actions ineffective and allows unauthorized users to retain full access even after an account is closed or a password is reset, exposing the system to prolonged unauthorized use and significantly increasing the impact of account takeover scenarios. This issue has been patched in version 5.8.
OrangeHRM is a comprehensive human resource management (HRM) system. From version 5.0 to 5.7, the password reset workflow does not enforce that the username submitted in the final reset request matches the account for which the reset process was originally initiated. After obtaining a valid reset link for any account they can receive email for, an attacker can alter the username parameter in the final reset request to target a different user. Because the system accepts the supplied username without verification, the attacker can set a new password for any chosen account, including privileged accounts, resulting in full account takeover. This issue has been patched in version 5.8.

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