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They built a DMG with a "fake" Flash Installer that doesn't verify codesigning or trigger the Gatekeeper warning.

• eridius 12y ago
  Their "fake" installer is a copy of an existing codesigned app (Instruments.app) and a directory structure that causes the app to load a library from outside its app bundle when launched. In this case, since it's loading a library outside of the app bundle, the code signature is intact. But beyond that, it seems no different than just writing an application that explicitly loads something from outside its bundle. The only benefit here is it can use someone else's codesigned app instead of having to get a certificate to codesign the app themselves. But that doesn't seem particularly meaningful. Assuming the library itself isn't codesigned, this does suggest an issue with Gatekeeper, wherein it doesn't validate all the libraries that are loaded by the application. If that's true, it seems like something that should be relatively easy for Apple to fix without affecting legitimate functionality (because any codesigned app has no need to load non-codesigned libraries). The results are also wildly overblown. The entire attack requires the user to open a downloaded DMG and run a contained app without copying the app. This is not something people do very often, and if this really is a serious threat, then a simple rule of "don't launch apps from DMGs" suffices (merely moving the app out of the DMG neuters the attack).