George Stathakopoulos had been general manager of Microsoft's Product Security and Security Engineering and Communications Group. There, he managed the company's various security programmes, which are collectively known as Trustworthy Computing. His last day with Microsoft, his employer since 1991, was Friday, Febuary 12.
Stathakopoulos left to work a security management job at Amazon, according to sources familiar with the matter.
He is replaced at Microsoft by Matt Thomlinson, formerly senior director of security engineering with the Trustworthy Computing group, a Microsoft spokesman said.
"George has had a long and noteworthy career at Microsoft, working on some of the company's most widely deployed products and security initiatives," he wrote. "In the past eight years since Trustworthy Computing was launched, George has made a significant impact through sustained focus on the security of Microsoft customers and the security of the IT ecosystem at large. We appreciate his service and wish him well. "
One of the original members of the Internet Explorer team, Stathakopoulos was a well-regarded manager at Microsoft who was credited with helping the company build bridges with the hacker community and secure its often buggy code.
"I've got nothing but good things to say about the guy," said security researcher Dan Kaminsky. Kaminsky's company, IOActive, has worked with Microsoft in the past.
Thomlinson, like his predecessor, will now report to Scott Charney, Microsoft's corporate vice president, Trustworthy Computing.
Amazon representatives did not respond to messages seeking comment for this story. Security is increasingly important to the company as it develops its Amazon Elastic Compute Cloud (EC2) web-based computing infrastructure. EC2 gives anyone access to Amazon computing resources, and security experts worry that it could be misused by criminals or hacked.