The incident, as revealed in the notification letters, occurred when the library system detected the incident on April 21 and decided to shut all library systems in an effort to control the breach. The library system conducted an investigation that confirmed the breach had taken place.
The library network was also able to identify that the exfiltration of data from individuals who utilized or were part of the institution was successful on May 12. It was established that the hackers had access to the network from April 15 to April 21. Access to sensitive information was gained and exfiltrated during this time. The level of information that was vulnerable varied depending on who was targeted.
The data that was breached for the benefit of the library patrons included names and dates of birth. Though very limited compared to the data for employees, this data is still significant for use in identity-related fraud. The breach had severe implications for current and former employees who worked within the library system. The data that was stolen for them included Social Security numbers, financial accounts, driver’s license numbers, credit card numbers, passports, health insurance, and certain data related to medical matters.
This particular ransomware assault would later be attributed to the INC ransomware gang, which has been responsible for a number of highly detrimental attacks on government bodies over 2025. The gang has previously conducted attacks on bodies such as the Office of the Attorney General of Pennsylvania and a countrywide emergency alert service used by local authority bodies.
This type of situation is not the first that has occurred on the level of Pierce County.
In the year 2023, Pierce County was the victim of a ransomware attack on the public transit service that the community utilized heavily because the service was used by 18,000 riders on a daily basis.
Public library networks have become a common target for ransomware attacks in recent years. This is because cybercriminals also perceive public libraries as high-stakes targets since community members depend on them for internet access to their catalogs and other digital services, creating a challenge where an organization may feel pressured into paying a ransom demand to resume operations. Such attacks also include national and city library networks in North America.
The current threat environment has led to calls for developing targeted programs within the government in the United States that would evaluate risks for libraries' cybersecurity environments. This involves enhancing data sharing related to cyber attacks and providing libraries with more support and advanced services from firewalls that target libraries specifically.
The increasing digitization efforts by libraries as government institutions further solidify that a breach such as that which Pierce County experienced is a reminder that a continued investment in cybersecurity measures is a necessity.
