Malware Authors Target Mozilla, Developers Respond with Enhanced Safeguards

Monday July 12th, 2004

Over the past few months, it has become apparent that many authors of malware (a category of malicious software that includes viruses and spyware) have started targetting Mozilla users. While it is not believed that any attackers have managed to exploit the XPInstall mechanism to install software without the user's consent, several sites have tried tricks such as repeatedly asking to install an XPI package when a page loads, taking advantage of the fact that many users will accept the installation to make the dialogues go away.

Fortunately, users of recent Mozilla-based browsers now enjoy several new security safeguards designed to protect against these sorts of attacks. During the 1.7 release cycle, Daniel Veditz developed a patch that blocks XPI installs from being triggered by a page load, preventing software installation dialogues from appearing as soon as a user visits a site (bug 238684). Later in the same release cycle, a whitelist of sites that are allowed to ask the user for permission to install software was implemented (bug 240552). The default whitelist for Mozilla 1.7 features, and (home of Firefox Help and Thunderbird Help). Mozilla Firefox 0.9 just allows (though this has since being expanded to the whole of

The most recent Firefox nightlies feature a new user-interface to manage the XPInstall whitelist. When a user tries to install software from a site that is not on the whitelist, a thin non-modal yellow bar appears at the top of the content area, informing the user that the install has been blocked (bug 241705). A button allows the user to add the site to the whitelist if they choose. Testers of the beta release of Windows XP Service Pack 2 will probably find the yellow bar familiar: it's almost a carbon copy of the new Internet Explorer Information Bar that appears when an ActiveX control is blocked. If you cannot wait for Firefox 1.0 to try this feature, grab a nightly build from the 0.9 branch but remember that there may be bugs.

#22 UI refinement

by smkatz

Tuesday July 13th, 2004 2:16 PM

You are replying to this message

OK | Install (two options instead of one.)

or the stronger version:

OK | Install Anyway.

OK closes the warning. Install Anyway installs the XPI with the usual XPI install prompt.

Is this good enough?

The only other option is that the first time an XPI is blocked, like the first time a pop-up is blocked, a modal explanatory window appears.

But in general, a novice user would not notice a non-modal display like this. We'll get more usability data when SP2 goes widespread. Tweaking the interface from SP2 should not happen unless we genuinely disagree with it, or think Microsoft is interested in patenting that interface in order to harm Mozilla.

In addition, the no XPI install on pageload patch should be enough to solve abuse. The existing XPI prompt is warning enough.