A hacker published code on Tuesday that exploits a vulnerability found in the latest version of the Mozilla Corp.’s Firefox browser.
The code, which targets the Firefox 1.5 browser, was posted on The Metasploit Project site by a hacker known as H D Moore. Metasploit is a widely used hacking tool.
Moore said that a hacker by the name of Georgi Guninski reported the flaw to the Mozilla Foundation on Dec. 6 of last year, and that he had simply implemented and posted the technique described by Guninski.
Mozilla published an advisory about the exploit last Wednesday as it released the Firefox 1.5.0.1 browser, which included a patch for the flaw.
According to the advisory, the vulnerability, which had been rated as moderate, causes a corruption in the browser’s memory that could be exploitable to run arbitrary code. Specifically, calling the “QueryInterface” method of the built-in Location and Navigator objects of the browser could allow a hacker to take over a Firefox 1.5 user’s system by tricking the user into viewing a maliciously encoded Web page.
Hacker Aviv Raff on Tuesday criticized Mozilla on his blog for under-rating the flaw. He has blasted the open-source group in the past for downplaying the seriousness of vulnerabilities that have been found in its software.
“My guess is that they are waiting for an exploit in the wild before they are going to rate any exploitable memory corruption vulnerability as ‘Critical’,” Raff wrote Tuesday.
Chris Beard, vice president of products for Mozilla, said Tuesday that the company was not aware of any known exploits to the flaw when it published the advisory, and so rated the vulnerability as moderate. However, the flaw will now be reclassified as “critical” since there is a possibility for remote code execution, he said.
The only version of the browser that is affected by the flaw is Firefox 1.5; older versions do not appear to be vulnerable, according to Mozilla. Moreover, most Firefox 1.5 users should now have automatically downloaded the software patch, thanks to the built-in automatic updates that Firefox now uses.
Thunderbird 1.5, the latest version of the group’s e-mail application, could be vulnerable to the flaw if JavaScript is enabled in mail, Mozilla’s advisory also warned. However, JavaScript enablement is not a default setting in Thunderbird, according to Mozilla.