The US Department of Homeland Security is advising Americans not to use the Internet Explorer Web browser until a fix is found for a serious security flaw that came to light recently. The bug was announced by FireEye Research Labs, an Internet security software company based in Milpitas, California.

It recommended that users and administrators “consider employing an alternative Web browser until an official update is available.” The security flaw allows malicious hackers to get around security protections in the Windows operating system. They then can be infected when visiting a compromised website. Because the hack uses a corrupted Adobe Flash file to attack the victim’s computer, users can avoid it by turning off Adobe Flash. “The attack will not work without Adobe Flash,” FireEye said. “Disabling the Flash plugin within IE will prevent the exploit from functioning.”