Turns out, Gatekeeper isn’t minding the store as well as previously thought. Mac Rumors is reporting on a new exploit that may allow
rouge rogue applications to bypass the security feature. It’s a reminder that even with security tools, you should still only download software you trust.
Even if Gatekeeper is enhanced to its highest level of security settings, the new exploit can take advantage of a computer. Once the trusted file makes its way past the security program, it can then execute a handful of other malicious programs attached with the rest of the installation and gains the ability to install malicious software such as password-stealing programs, apps that can capture audio and video from a Mac’s camera, and botnet software
Source: New Mac Exploit Easily Bypasses Gatekeeper Security, Could Allow Installation of Malicious Apps