Security Exploit Uses Internet Explorer to Attack Mozilla Firefox
Wednesday July 11th, 2007
Firefox_User sent us a link to a CNET News.com article about a security threat to Windows users with both Mozilla Firefox and Microsoft Internet Explorer installed. The issue can allow an attacker to remotely trick Firefox into executing potentially malicious code. However, a user has to be running Internet Explorer to actually get exploited.
There's some debate as to where the blame lies — is it IE for passing untrusted data to another application or Firefox for not validating input properly? SecurityFocus refers to the problem as a Microsoft Internet Explorer FirefoxURL Protocol Handler Command Injection Vulnerability, placing the blame with Redmond, while Secunia calls it a Firefox "firefoxurl" URI Handler Registration Vulnerability, pointing the finger at Mozilla. News.com quotes Oliver Friedrichs of Symantec's Security Response Center, who says, "It's a little bit of both."
On the official Mozilla Security Blog, the Mozilla Corporation's Window Synder (who used to work for Microsoft) says that a fix will be included in the forthcoming Firefox 188.8.131.52. That said, she seems to suggest that she considers this to be mostly a problem with IE, noting that Apple fixed a similar issue with Safari recently. However, according to the ZDNet Zero Day security weblog, Microsoft claims the firefoxurl:// bug "is not a vulnerability in a Microsoft product".
Thanks to roseman for some of the links used in this report.
#17 Sanity Checks re: Security Exploit
Thursday July 12th, 2007 3:48 PM
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Two key issues:
1. Merely having both IE and Firefox on the same computer is not a problem. The vulnerability occurs only when browsing with IE and then only if the user selects a link that begins firefoxurl:// instead of http://, https://, etc. Thus, if you browse only with Firefox (or another Gecko application), the problem does not occur. (I use IE only to get the too frequent Windows patches and occasionally to check how my own Web pages appear with a non-Gecko browser.)
2. It appears that SeaMonkey (the browser I use) does not register a firefoxurl protocol. The string "firefox" does not appear in my WindowsXP registry.
What we have not yet seen here is an explanation of the purpose of the firefoxurl protocol. If it has no purpose (thus answering why there is no explanation) or it was never completely implemented, it should be removed.