Mozilla Privacy Bug

Saturday September 14th, 2002

Yesterday, ZDNet UK News reported that Mozilla has a privacy flaw involving HTTP referers. The flaw can be exploited using the onUnload JavaScript handler, which is triggered when a visitor leaves a page (for example, by clicking a link or using a bookmark). The problem is that the referer Mozilla sends is the URL of the page that the visitor is going to, not the page that he or she is exiting. This means that a site can discover where you are heading when you leave.

The security bug is present in the latest versions of Mozilla (including 1.0.1, 1.1 and 1.2 Alpha) as well as some Mozilla-based browsers, such as Netscape 6.x, Netscape 7.0, Galeon 1.2.x and Chimera 0.5. At the time of writing, no fix is available. A workaround is to disable JavaScript (Edit > Preferences > Advanced > Scripts & Plugins).

A demonstration of the exploit has been created by security researcher Sven Neuhaus, who posted details of the vulnerability to Bugtraq on Wednesday.

The bug was filed in Bugzilla as bug 145579 on Sunday 19th May, with the more serious onUnload behaviour found on Friday 7th June. The report is currently marked as "Security-Sensitive" and access to it is restricted in line with the Mozilla Security Bugs Policy.

UPDATE! Bug 145579 has now been made public.

ANOTHER UPDATE! A fix has been checked in to the trunk. A patch for the 1.0 branch will follow shortly.

YET ANOTHER UPDATE! A patch has now been checked in to the 1.0 branch.

#42 Re: Re: Track Record

by shin

Tuesday September 17th, 2002 7:04 AM

You are replying to this message

> Where the hell is your head? No kidding! I wouldn't expect a browser with > such miniscule usage status to be the target of any evil freak that druels > over the thought of creating headaches for the masses.

You don't need to be an evil freak to wreak havoc in Mozilla: the source is open, so you can find security holes easily if there are any.

It's surprising how many opensource projects, whose source is available for all the evil hackers to see, are often more secure than closed-source projects... But I guess you're going to tell us opensource projects don't have a track record. Funny, funny.