Asahi restarted six of its breweries in Japan on Thursday after a cyberattack forced the beer maker to halt production and shipments for several days.

The drinks company is still investigating the root cause of the incident and also assessing the potential impact on earnings, a spokesperson said on Monday. Asahi had earlier said that most of its 30 plants in Japan temporarily stopped production, but did not disclose how many were affected due to the hack.

Some parts of the system are still shut and the company is processing orders manually to prioritize its supply framework, Asahi’s spokesperson said, adding that the timeline for full restoration of systems remains uncertain.

The ransomware attack sparked concerns that retailers may soon run out of Japan’s most popular beer Super Dry. Retail chains Seven & I Holdings, Lawson and FamilyMart had warned customers of possible shortages of the top-selling brew in the coming days.

The outage at Asahi, which started Sept. 29, is the latest among a growing wave of cyber incidents globally, that have hit industries from carmakers to financial firms. The hack underscores Japan’s vulnerability to cyberattacks, where even brief halts can ripple from factory floors to store shelves and restaurants given the country’s intricate supply chains.

Asahi will need to slash its fourth-quarter operating profit outlook by approximately 83% in Japan and 38% globally, if the disruption continues through the end of this month with no corrective actions, analysts at Sanford C. Bernstein Japan led by Euan McLeish said in a note to clients on Friday. The company may also have to face out-of-stock penalties from major retailers, they said.

Shares of Asahi rose 1.6% in Tokyo on Monday, after a more than 7% plunge last week.