The week after an exploit that takes advantage of the way that iOS devices handle PDF files was announced, Apple has released a patch designed to fix the problem. The patch is included in iOS 4.3.4 for iPads and later-generation GSM iPhones and iPod touch devices; CDMA iPhone 4 users can install iOS 4.2.9. In either instance, the software update must be downloaded through iTunes; the download is a complete system image.
Last week, the Dev-Team hacking group released an update to its JailbreakMe.com site that used a flaw in the way that the Core Graphics functions of iOS handle PDF files; specifically, the FreeType subsystem was allowing buffer overflows when rendering TrueType fonts, and a signedness issue affected FreeType’s rendering of Type 1 fonts. Although the JailbreakMe.com site was not installing a malicious payload, its method of subverting iOS was seen as a disturbing proof of concept.The iOS updates also include a fix for the queuing primitives of the IOMobileFrameBuffer, which were allowing code to execute when an invalid type conversion was triggered.
Apple required as much time to release this patch as it did last year, when addressing a related JailbreakMe.com exploit. It’s unclear if that window between Day 0 of the exploit and its resolution is simply as small as one can expect, or if Apple’s development resources are so committed to the forthcoming iOS 5 that security issues are taking a back seat for now.
In any event, I’m looking forward to iOS 5, if only for the promise of incremental updates to the mobile OS, rather than the current practice of requiring users to download the complete system image every time a new vulnerability is found.