The breach came to light after the company investigated a systems outage at a Lansing, Michigan, franchise in January 2025. According to a filing with the Office of the Maine Attorney General, attackers gained unauthorized access to Manpower’s network between December 29, 2024, and January 12, 2025. In notification letters sent to affected individuals, Manpower revealed that certain files may have been accessed or stolen during this time. The company stated that the breach potentially exposed personal information, though the full scope of data compromised remains undisclosed.
On July 28, 2025, the staffing firm formally notified 144,189 individuals that their data may have been involved in the incident. Following the discovery, Manpower announced that it had implemented stronger IT security measures and is cooperating with the FBI to pursue those responsible. To mitigate the impact on victims, the company is also offering complimentary credit monitoring and identity theft protection services through Equifax.
The ransomware group RansomHub has claimed responsibility for the attack. In January, shortly after Manpower disclosed the incident, the group alleged that it had stolen 500GB of sensitive files from the company’s systems. According to RansomHub, the stolen trove included personal and corporate records such as passports, Social Security numbers, contact details, financial documents, HR analytics, and confidential contracts. The gang initially published details of the breach on its dark web site but later removed Manpower’s listing, raising speculation that a ransom may have been paid to prevent further data leaks.
RansomHub is a ransomware-as-a-service (RaaS) operation that emerged in early 2024, evolving from earlier groups known as Cyclops and Knight. Since then, it has been linked to numerous high-profile attacks against global organizations, including Halliburton, Kawasaki’s European operations, Christie’s auction house, Frontier Communications, Planned Parenthood, and the Bologna Football Club. The group was also behind the leak of data stolen in the massive Change Healthcare cyberattack, one of the largest breaches in the U.S. healthcare sector, impacting more than 190 million individuals.
Last year, the FBI reported that RansomHub affiliates had breached over 200 critical infrastructure organizations across the United States, further underlining the group’s reach and persistence. While ManpowerGroup has not confirmed the exact nature of the stolen data or whether negotiations occurred, a company spokesperson clarified that the incident was confined to an independently operated franchise in Lansing. The spokesperson emphasized that the franchise runs on a separate platform, meaning no ManpowerGroup corporate systems were compromised.
The breach highlights the growing risks ransomware attacks pose to global enterprises, particularly those handling large volumes of sensitive employee and client data. It also reflects how threat actors like RansomHub continue to exploit vulnerabilities in third-party and subsidiary operations, targeting organizations indirectly when direct access to corporate systems is more difficult.
