Taiwanese PC maker Acer is investigating the hacker attack that stole customer data from its Packard Bell unit in Europe, according to a statement from the company. Acer said the security breach was limited to customers' names, addresses, phone numbers, emails, and system serial numbers. No credit card data was stolen, it said. Acer provided no other information about the attack, and said the investigation was still under way. News of the breach was reported earlier this month, after a hacker group Pakistan Cyber Army claimed to have stolen the personal data of about 40,000 people from an Acer server in Europe. Acer did not comment on the attack at the time.The Hacker News had published screen shots of the personal data and some of the source code that was stolen in the security breach. It also said that the Pakistan Cyber Army would issue a press release detailing more about their motives. But so far, no new information has surfaced from the hacking group. The hacking group may be the same one that defaced the website of India's Central Bureau of Investigation in December. The hackers called themselves the "Pakistani Cyber Army" and left a message saying that the breach was in revenge for similar Indian attacks on Pakistani sites.