Firefox 0.9.2, Thunderbird 0.7.2, Mozilla 1.7.1 Coming Soon

Thursday July 8th, 2004

Branches have been created for three of's latest releases, in order to fix an external Windows protocol handler bug. The fix involves disabling the shell: protocol handler, which was found to enable pages to run executables on Windows via a link. Builds should officially be available shortly, and there will also be an XPI offered to disable the pref. Alternatively, you can set the pref in about:config to false to remove the exploit. (This will only set it on your current profile, if you have more than one profile, or could be creating more, you should use the XPI or the updated build.)

More information about the exploit can be found in this post on the FullDisclosure mailing list.

Update: The XPI to disable the pref is now available.

Another Update: has published a document on the issue.

Yet Another Update: There is an eWeek article about the exploit as well as a discussion at Slashdot. The now public bug report that covers the shell: vulnerability is bug 250180 (no unnecessary comments please). Some may find it notable that a patch was issued less than forty-eight hours after this bug was filed.

Yet Another Update: If you are not using Windows, you are not at risk from this bug. If you are using Windows, go to to see if you are vulnerable.

#47 Re: Re: Only fix in 1.7.1

by superyooser

Saturday July 10th, 2004 11:57 AM

You are replying to this message

I thought all they did was add shell: to a blacklist. How do you explain these bizarre file size differences?

Mozilla 1.7.1 win32 zip 11,366,599 bytes Mozilla 1.7 win32 zip 11,366,834 bytes -235 bytes (less!)

Mozilla 1.7.1 win32 installer-exe 12,042,960 bytes Mozilla 1.7 win32 installer-exe 12,378,832 bytes -335,872 bytes (less!)

Firefox 0.9.2 win32 zip 6,317,526 bytes Firefox 0.9.1 win32 zip 6,283,289 bytes 34,237 bytes Firefox 0.9.2 win32 setup-exe 5,078,944 bytes Firefox 0.9.1 win32 setup-exe 4,959,023 bytes 119,921 bytes