A security update locked OSX.GenieoDropper.A I need to launch an app but OSX recognise it as a malware. 

While launching this app, OSX says "app will damage this computer. You should eject this disk image. It contain OSX.GenieoDropper.A".

Normally, to bypass this alert, the method was to right-click the icon and select open when pushing alt, but neither this seems working, so how can I bypass this alert?
Sorted: type in the terminal

xattr -d com.apple.quarantine

leave a space after "quarantine" and then drag &amp; drop the .app file.

Then press Return...et voila'!

The -cr flag is for operating systems before (and including) Mavericks. For newer operating systems (Yosemite &amp; El Capitan) you must specify the flag -d along with the attribute (com.apple.quarantine) you wish to remove.