Microsoft's web browser has suffered a major hacking attack.

A flaw has just been found in a recent version of Internet Explorer and it's being used to attack people online, including some visitors to one of the main sites for US military vets.

Security firm FireEye Incorporated found the attacks against I.E. version 10 this week and it says hundreds or maybe even thousands of machines have been infected.

Hackers broke into the Veterans of Foreign Wars website and redirected browsers to a malicious page that plants spyware and malware in computers.

Microsoft says it's aware of the hack, and it recommends people make sure they have the latest version of the browser, IE 11.