The employee, who spoke to Business Insider on the condition we kept their anonymity, said there are a lot of people trying to get hold of Apple's inside information.
"You'd be surprised how many people get on to us, just random Apple employees," the source said. "You get emails offering you thousands [of euros] to get a password to get access to Apple.
"I could sell my Apple ID login information online for €20,000 (£15,000 / $23,000) tomorrow. That's how much people are trying."
Another former Apple employee confirmed to Business Insider that hackers contact Apple staff and offer them money in exchange for login details or company information. "They look for someone who has jumped diagonally into a junior managerial position, so not a lifer working their way up, and not a lifer who has been there a long time," the former Apple employee said, adding that Apple launched a scheme called "Grow Your Own" as a response to the problem. (It is not clear why the scheme is named Grow Your Own.)
Our sources did not know what the hackers are after. Unauthorised access to Apple's internal systems would provide a treasure trove of valuable data for criminals. They may be targeting individual user accounts, or they could be after intellectual property, or corporate strategy data. The source said Apple is "very, very careful" in terms of security, adding that it's exceptionally hard for anyone to gain access to Apple's offices without authorisation.
Even some of Apple's remote workers in Ireland have difficulty accessing the company's offices in Cork, where thousands of Apple workers are based, the source said. "You have to have a particular coded badge to get into the building," they explained.
Business Insider has contacted Apple to find out more and is waiting to hear back.