patrickportwilliam wrote:
Okay, so how did it bypass Apple's security?
First, the Genieo installer is a signed app. This means that the Genieo folks obtained a developer ID from Apple, and with it, a cryptographic certificate that can be used to sign their software. This means that they are an "identified developer," and thus the app will be allowed to open (with a warning) when using the default setting for System Preferences -> Security & Privacy -> General -> "Allow apps downloaded from". (The default is "Mac App Store and identified developers").
Second, Genieo has never been added to the anti-malware system (XProtect) built into Mac OS X.
Apple could revoke their developer ID and the certificate if they felt it was being abused to create malware. They could also add identification of Genieo to XProtect. Either of these things would be sufficient to prevent Genieo from installing. However, Apple has not done so, probably because Genieo simply hasn't crossed that line from annoying to outright malicious. There is a school of thought that adware is legit, because it allows some apps to remain free rather than requiring payment. Presumably, this is why Apple has not taken action to block Genieo.
I'd strongly encourage leaving feeback for Apple, as MadMacs0 has suggested, to let them know how you feel about Genieo.