Apple has quietly hired Kristin Paget, a former Microsoft security expert who worked as a hacker for the company to resolve Windows Vista vulnerabilities, to work on its Mac OS X security team.

According to her LinkedIn profile, Paget (formerly known as Chris Paget) was hired as Apple's Core OS Security Researcher in September.

Paget confirmed that she is now an Apple employee in an email to Wired, but referred all questions to Apple's public relations group, in keeping with the company's usual secrecy.  An Apple spokesperson decline to comment.

Apple's decision to hire Paget indicates that the company is acting on the growing amount of Mac malware. Earlier this year, more than 600,000 Mac were reported to have been infected with a Flashback Trojan that was being installed on people's computers with the help of Java exploits. This led experts to put Apple security in the spotlight.

During her time at Microsoft, Paget had been forbidden from speaking about her role until five years after she had left the company.

So in 2011, when the five year period was up, Paget revealed at the Black Hat Las Vegas conference that Microsoft had believed its Windows Vista was secure when they had given it to her before its launch, but were forced to delay its release after Paget discovered many flaws in the operating system. 

"We prevented a lot of bugs from shipping on Vista," she said. "I'm proud of the number of bugs we found and helped get fixed."

When Paget and Microsoft's team of hackers had finished solving the problems in Vista, they received humorous T-Shirts signed by Microsoft VP of Windows Development Brian Valentine that read 'I delayed Windows Vista' for their efforts.

On Twitter in July, when Paget was asked what her ideal job would be, she wrote: "Building things, ideally security focussed hardware. I've done too much breaking of things, it's time to create for a change."

Paget is widely known as an accomplished hacker, and among her accomplishments was setting up a cell phone call intervention system at hacking conference Defcon.

See also:

New 'Dockster' malware targets Apple computers

Tim Cook explains execuitve shakeup: 'It's all about collaboration'

New Mac malware stealing passwords

Watch Tim Cook's NBC interview in the UK

Tim Cook: 'We screwed up'