Mozilla downplays Firefox bug, passes on fix

Gregg Keizer
19 August, 2010
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Mozilla on Tuesday said that it will not patch a bug that blocks the display of a warning when Firefox detects a potentially deceptive URL, saying the flaw was not a threat.

“This issue poses very low risk to users,” said director of Firefox development Johnathan Nightingale, in an entry yesterday to Mozilla’s security blog. “There is currently no fix in plan since Mozilla does not believe this can be used to attack users.”

Others backed Mozilla’s decision to ignore the bug.

Michal Zalewski, a Google security engineer who frequently submits Firefox vulnerabilities, called the bug report a “non-issue”, and in a message to Bugzilla, Mozilla’s change- and bug-tracking database, asked, “…why [is] this even being seriously discussed?”

The flaw was reported last June to Mozilla by Aditya Sood, a researcher with Santa Clara, California-based web security firm Armorize. Sood blogged about the bug Tuesday, saying that Firefox failed to pop up its usual warning of a misleading URL when that address was passed to the browser via an IFRAME planted on a hacked or malicious site.

Sood’s post sparked stories by several technology sites and publications, and prompted Mozilla’s Nightingale to issue his appraisal.

“This attack relies on user confusion about the true destination of a link, and only someone examining the HTML source of the page would ever see the deceptive URL,” added Nightingale. “Most users do not view the source of loading pages, and are therefore unlikely to be impacted by this attack.”

Mozilla developers had questioned Sood’s bug long before this week.

“We trigger an error when loaded via the location bar because the user might be fooled by the text in the location bar not matching the site they’re seeing,” explained Firefox developer Gavin Sharp on Bugzilla two months ago. “When loaded in an iframe, there’s no confusion, because we don’t show the URL anywhere – so there’s no benefit to having the iframe load ‘’ vs. just loading ‘’ directly.”

Zalewski was harsher in his criticism of Sood’s bug report than Mozilla. “There is no reasonable attack scenario where this would matter,” he said in an entry on his personal blog. “It’s common sense, too: You don’t need to be able to tell a buffer overflow from a format string vulnerability to understand why.”

He also blasted the media sites that reported on the Firefox flaw, and contended that Sood’s report was unworthy of coverage. “[These stories] should never have seen the light of day in the first place,” Zalewski said.

Zalewski isn’t the first security researcher to take reporters to task this summer.

In a June epistle to the Dailydave security mailing list, researcher Brad Spengler knocked Microsoft and the press for linking Tavis Ormandy – the researcher who revealed a critical Windows vulnerability five days after reporting it to Microsoft – to his employer, Google.

Ormandy got in his own shots as well.

Last week, he told other security researchers he would disclose several vulnerability advisories, but was not going to release them publicly. “I’ve prepared some advisories for today, but I’m reluctant to release them publicly as journalists have been raping my work for pageviews,” Ormandy said in a tweet, apparently referring to the stories that ran in June and July about the Windows bug he had unveiled.

In other tweets, Ormandy accused security reporters and bloggers of fabricating stories, of being “cruel” and “dishonest,” and “driven by drama.”

Mozilla plans to issue the next set of Firefox patches 7 September with updates to Firefox 3.5 and Firefox 3.6.

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