Month of Apple Bugs - Day 1

01 Jan 2007, 22:08 PST

I stumbled across the Month of Apple Bugs today -- a new Mac OS X vulnerability released every day for a month.

Today's vulnerability exploits a stack buffer overflow in the QuickTime Streaming component, and includes a working x86 exploit. More details available here. Short summary: if you visit a malicious web page, a remote attacker can execute code on your machine.

So, part brain exercise, part public service, I've created a runtime fix for the first issue using Application Enhancer. If I have time (or assistance), I'll attempt to patch the other vulnerabilities, one a day, until the month is out.

You can download the source, or download a pre-built binary. You'll also need to install Application Enhancer to use this -- once it's installed, simply double-click on the Moab bundle to install the patch.

I've had one report of the Moab bundle showing up in the Finder as a plain directory. If that occurs, try manually adding the bundle from the Application Enhancer preference pane, in System Preferences (Hit the "+" button).

Technical Details -- How it Works

The overflow is in the QuickTime Streaming component's INet_ParseURLServer() function -- the fix patches that function and pre-validates the URL before passing it off to the real function implementation. If the URL is too long, the patch replaces the Evil URL with a benign, but invalid one, and then calls the original function.

It's worth noting that disabling RTSP, as noted elsewhere, is (unfortunately) not necessarily sufficient -- there are other vulnerable entry-points to INet_ParseURLServer(), as it is used for generic URL parsing.


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