Wednesday, July 28, 2010

Unpacking a Safari Extension

So, now that Safari extensions are official (and not just a developer curiosity), I decided to see what people had managed to make over at the extension gallery. It looks like there are some cool ideas out there. I was somewhat interested in the Exposer extension, which sounded a bit like Exposé for Safari. It seems like it kinda works, except that it doesn't always bring up the list of windows, and it's also really slow (it looks like visibleContentsAsDataURL is the culprit, natch, plus I have dozens of tabs open at a time).

Anyway, while I was checking it out, I realized that I had no idea what some of these Safari extensions were doing in the background. Stop and think for a moment; do you really want to run code that some Jimmy wrote in his basement to be able to watch everything that you do in your browser? Maybe I'm just paranoid, but I'd like to know what is really going on.

So, naturally, I tried unpacking an extension. It wasn't particularly hard, but you have to realize that a .safariextz file isn't a ZIP archive. It's a XAR. I know; I opened it up in my hex editor.

Here's how you can unpack one for yourself:

xar -xvf extension.safariextz -C ~/Desktop

Don't worry; there's a directory just inside the safariextz archive. Now to see if there's anything malicious in these extensions. (Exposer looks clean so far.)

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