Systems Affected: Apple QuickTime 6.5 Apple iTunes 4.2.0.72
Description: The Apple QuickTime media player is used for playing, interacting with or viewing video, audio, VR or graphics files. Many popular web browsers, media players, and other applications use their libraries to play various QuickTime movie formats through their applications.
eEye Digital Security has discovered a critical vulnerability in QuickTime Player. The vulnerability allows a remote attacker to reliably overwrite heap memory with user-controlled data and execute arbitrary code within the SYSTEM context.
This specific flaw exists within the QuickTime.qts file which many applications access QuickTime's functionality through. By specially crafting atoms within a movie file, a direct heap overwrite is triggered, and reliable code execution is then possible.
Technical Details: The code in QuickTime.qts responsible for copying Sample-to-Chunk table entries from the 'stsc' atom data in a QuickTime-format movie into an array allocated on the heap. According to developer.apple.com, the format of the Sample-to-Chunk atom is as follows:
Offset Type Description ------- ------- -------------------------------- 0000h DWORD atom size 0004h DWORD atom type tag ('stsc') 0008h BYTE version 0009h BYTE[3] flags 000Ch DWORD number of entries 0010h ... sample-to-chunk table data
The heap block intended to hold the sample-to-chunk table data is allocated with a size equal to (number_of_entries + 2) * 16. By supplying the "number of entries" field with the value 0x0FFFFFFE or greater, an absolutely classic integer overflow results that causes an insufficiently-sized heap block to be allocated, resulting in an equally classic complete heap memory overwrite.
It is difficult to express just how textbook this vulnerability scenario really is. Successful exploitation of the vulnerability is self-evident, and therefore no further discussion is warranted. It is our sincere hope that the vendor will make an earnest effort to increase the maturity of its security response capabilities, so that researchers will be encouraged to continue to work with them amicably on future security issues. Apple is doing a disservice to its customers by incorrectly labeling this vulnerability as a "crash bug" rather than stating correctly that attackers can compromise systems running the affected Apple software.
