Data storage giant Western Digital has confirmed that hackers exfiltrated data from its systems during a “network security incident” last week.

The California-based company said in a statement on Monday that an unauthorized third party gained access to “a number” of its internal systems on March 26. Western Digital hasn’t confirmed the nature of the incident or revealed how it was compromised, but its statement suggests the incident may be linked to ransomware.

“Based on the investigation to date, the company believes the unauthorized party obtained certain data from its systems and is working to understand the nature and scope of that data,” Western Digital said.

It’s not yet known who was behind the attack. The incident does not appear to have yet been claimed by any major ransomware group.

Western Digital notes that the incident “has caused and may continue to cause disruption” to the company’s business operations. The company didn’t provide any further information. At the time of writing, Western Digital’s service status website confirms that the incident downed its My Cloud network-attached storage (NAS) service, which allows customers to access their files from the internet.

Western Digital said it is “implementing proactive measures to secure its business operations” and is working to restore impacted infrastructure and services. The company added that it is investigating the incident with an unnamed cybersecurity firm and coordinating with law enforcement.

Western Digital declined to comment or answer TechCrunch’s questions.

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