In a presser, the company revealed that hackers gained access to Opera Sync, a service that lets users synchronize their browser data and settings across multiple platforms. It is investigating the incident, but initially believes the attack may have compromised user data, including passwords and login names. According to the company a small section of its 350 million users who use Opera Sync service were affected by the breach. Opera said it counted 1.7 million active Sync users, but more may have registered for it and, in doing so, provided Opera with data. The company has reset all passwords and emailed all registered Opera sync users with details. “Although we only store encrypted (for synchronized passwords) or hashed and salted (for authentication) passwords in this system, we have reset all the Opera sync account passwords as a precaution,” it explained in a blog post. The hack attack comes nearly a month after Opera announced the sale of its browser business, privacy apps and Chinese joint-venture to a consortium from China led by anti-virus firm Qihoo 360 for $600 million. More details about the data breach incident are awaited.