Researchers at cybersecurity firm Kaspersky Lab found out that recent Asus’ software update system was hacked and used to distribute malware to millions of its customers.

The malware was masked as a  “critical” software update, which was distributed from the Asus’ servers. The malicious malware file was signed with legitimate ASUS digital certificates that made it look an authentic software update from the company, Kaspersky Lab says.

 The report of the hack was first reported by Motherboard, and Kaspersky Lab plans to release more details as soon as possible at an upcoming conference.

The intentions of hackers behind doing this is not clear. However, from the early investigation, it is reported that the hackers seem to target a bunch of specific Asus customers as it contains special instructions for 600 systems, which is identified by specific MAC addresses.

Till now, Asus has not contacted any of its affected customers or taken any step to stop the malware. In an email interview with the Verge, Asus said that they would issue an official statement on the malware tomorrow afternoon.

According to the Motherboard, Asus apparently denied that the malware had come from its servers.

“This attack shows that the trust model we are using based on known vendor names and validation of digital signatures cannot guarantee that you are safe from malware,” said Vitaly Kamluk, Asia-Pacific director of Kaspersky Lab’s Global Research and Analysis Team who led the research.