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2 Firefox Security Flaws Lead to Exploit Potential
Marthisdil points out a News.com story which reports that "Two vulnerabilities in the popular Firefox browser have been rated "extremely critical" because exploit code is now available to take advantage of them." Security firm Secunia reported the vulnerabilities (and the "extremely critical" rating is theirs), but the News.com story points out that thus far, "no known cases have yet emerged where an attacker took advantage of the public exploit code." Update: 05/09 20:20 GMT by T : Rebron of the Mozilla Foundation sends a correction; this is really the same flaw reported yesterday. He suggests that you glance at the Mozilla security alert on this hole (as well other alerts at the Mozilla Security Center), and says "The Mozilla Foundation has made changes to our update servers that will protect users from this arbitrary code execution exploit."
http://it.slashdot.org/article.pl?sid=05/05/08/135 217&tid=154&tid=172
Before everyone freaks out, take a look at the bug notes to get the details.
Exploitation requires the javascript bug AND a whitelisted site. The only default whitelisted site is the update.mozilla.org, and they have made changes to mitigate the problem on their end.
So unless you've whitelisted a lot of extra sites to install themes or extensions, this is not a huge risk. To be sure, disable install "Allow websites to install software" under options | web features, and if really worried, disable javascript.
Correct.
One report says as follows:
Because the foundation controls all sites in the default software installation white list, it has been able to take preventative action by placing more checks in the server-side Mozilla Update code and moving the update site to another domain.
The foundation said users who have not added any additional sites to their software installation white list are no longer at risk.
So one down, the other to be fixed shortly.
Richard Steven Hack - This sig is TOO GODDAMN SHORT TO DO ANYTHING USEFUL WITH! MORONS!
Does Microsoft offer bounties to those who find, and alert them to, security problems? Not as far as I know. This, along with the opensource nature of Firefox will eventually make it mature into a more solid product than IE is likely to be unless Microsoft changes it's attitude. Security is, and always has been, a goal with Firefox. That just isn't true of IE. Also Firefox has the benefit of 20/20 hindsight with it's design as it was designed after many important types of exploits were discovered whereas IE's codebase is much older.
:)
Overall, I think Firefox is more secure than IE and will just grow to be increasingly more secure with time. That doesn't mean it is flawless.
At what price learning? At what cost wisdom? The price is a man's peace of mind, and the cost is his life.
From a news report:
Because the foundation controls all sites in the default software installation white list, it has been able to take preventative action by placing more checks in the server-side Mozilla Update code and moving the update site to another domain.
The foundation said users who have not added any additional sites to their software installation white list are no longer at risk.
So one down, the other to be fixed shortly.
Meanwhile I got a notice this morning that tomorrow's Microsoft security patch will fix one major flaw, but leave others unpatched UNTIL NEXT MONTH.
So much for "days of unpatched vulnerability" supposedly favoring Microsoft.
Richard Steven Hack - This sig is TOO GODDAMN SHORT TO DO ANYTHING USEFUL WITH! MORONS!
On Saturday, the Mozilla Update team, plus some Mozilla devs, took steps which prevented all published exploits we'd found from working. On Sunday, Mozilla Update was moved to an untrusted URL; as a result, users who have not added other sites to their whitelist should now be safe from the remote code execution attack.
My server
Tools/Options/Web Features/"Allow web sites to install software" - uncheck it. I don't know why this isn't unchecked by default.
It takes just a moment and an action to destroy. It takes some time and thought to create.
Yeah - it could even put a little red "update" button on the taskbar whenever ... oh. Right.
Firefox bugs get on the front page when they are exploitable in theory (this exploit here also worked only for a couple of hours because Mozilla's servers have been modified so Firefox is redirected to a non-whitelist site) while IE bugs get on the front page only when they cause serious mass infections.
Another post mentions that someone is claiming an 0-day exploit in the wild for these issues.
:)
From BT:
Firefox Remote Compromise Technical Details
Before I start, I need to say that this thing has been patched on Mozilla's server. If you take a look at any of the extension install pages on their site, you will see that the install function has a bunch of random letters and numbers after it. Even though this would probably be an easy thing to bypass, I am not going to attempt it because of the uselessness of such a bypass. A patch is already in development and so any more work going into fine-tuning this exploit would be a waist of time.
There are three core vulnerabilities being used in my example. A friend of mine (Michael Krax, http://www.mikx.de/ helped me with the research.
To understand why the example works, one must understand the basics of how Firefox works. Everything you see in firefox is essentially a webpage being rendered by a compiler. This is what the gui is made of, and this is why firefox is so easy to customize. However, it also allows for some security bugs. If one could get one of the chrome pages to request a javascript:[script] url, that individual would be given complete access to the system because chrome urls are given full rights in firefox. My example works by tricking the addon install function into displaying an icon with a javascript url.
However, this would not be enough to compromise the system. By default, the install feature only works when called from a page within update.mozilla.org or addon.mozilla.org. Therefore, another (cross site scripting) vulnerability had to be found to call the install feature from mozilla.org. This vulnerability navigates to a javascript page and displays a link (pointing to a mozilla.org page) within a frame that follows the user's cursor. After the user clicks, the link is navigated to, which fires the onload event. This is a buggy event in Firefox because with it we can now access certain parts of the window object that we shouldnt, such as the history object. After the page loads, we use the history object to navigate backwards to the javascript page. The javascript is executed again, now from update.mozilla.org because when we navigated backwards, we essentially navigated to a javascript:[script] page. Now we call the install addon feature, which displays a dialog with det
ails of the requested addon, including an image with a specified image. This image points to a javascript:[script] url, which gets executed in the context of chrome. Now we have compromised the system
Whew, that was quite a mouthful.
I am still trying to gather all the details as to how my research was leaked, but recent conversations are leading me to believe that it was a misplacement of trust, not a server compromise. However, I do not want to jump to conclusions too quickly, as this will only lead to more problems. That's all I will say about that subject, as I don't want to offend anybody.
Also, I would like to let everyone know that this is not the only vulnerability that Mikx and I have found. We still have a couple of tricks up our sleeves, and you can be sure that we will not make the same mistake twice.
If you want to see the original PoC, here is the url:
http://greyhatsecurity.org/vulntests/ffrc.htm
Paul
Greyhats Security
http://greyhatsecurity.org/