On the iPhone PDF and kernel exploit

As most of you already know, there are two open, critical vulnerabilities in iPhone OS versions from 3.x up. The first one resides in the Compact Font Format component of the PDF renderer and the second one an error in the kernel, allowing attackers to bypass the sandbox (SeatBelt) inside which applications are run on the iPhone.

The two vulnerabilities were discovered by @comex, @chpwn and other people.

Only few weeks later the .lnk design flaw on windows (guys, you’re using LoadLibraryW to load a damn icon!), these iPhone OS vulnerabilities are even more interesting, because of the way the release is being handled by the community and the vendor.

I spent 3 hours last night trying to find detalied information about the bug, and except confused (and propagandistic) blog posts the only bit of information is in this tweet, and in the actual pdf exploit running on jailbreakme.com. Where are the security lists posts? Where is the CVE? Even the CERT still doesn’t say anything about this vulnerability.

There’s something terribly wrong going on: the cat-and-mouse-game that is making the iphone-dev team researchers not disclose any of the vulnerabilities they find has become very dangerous for end users: an exploit that allows remote code execution and jail escape without no interaction whatsoever by the user, carried via something that’s used to consider “safe” (a PDF file) is what is called a critical hole; while the exploit that uses it is called a 0-day. It’s the first time in my life I see a 0-day packaged and distributed explicitly via a web site.

Anyway, the dev-team researchers did not have any other choice: if they had communicated with Apple prior to public disclosure, we wouldn’t have had a so easy jailbreak vector; OTOH now we have vulnerable phones and pads that can be very easily exploited by mailcious parties. It’s also funny that in order to be warned when a PDF is about to be loaded thus mitigating the risk, you should jailbreak your device and install the PDF Loading Warner afterhand.

My stand on this is that the real problem is Apple itself: they’ve crated a walled garden, outside any legislation, where they’re the absolute god and give and take whatever they want. It’s not gonna work forever. I really hope that people will understand think that it’s not the hackers’ fault, rather it’s the totalitarian companies’ fault, for not giving us control over the devices we buy from them. Hackers are only trying to liberate them, and it’s fair use under the DMCA, after all.

UPDATE 2010-10-05: I’ve posted a summary of this bug on the full-disclosure mailing list – you know, if it’s not on FD no one would think about it :-).

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