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custom_encode.py
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78 lines (58 loc) · 2.04 KB
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#!/usr/bin/python
from random import randint
import sys
def fbxencode(shellcode):
iv = '%x' % randint(1,0xffffffff)
t = iter(iv)
iv = '\\x' + '\\x'.join(a+b for a,b in zip(t, t))
while ('\\x00' in iv):
iv = '%x' % randint(1,0xffffffff)
t = iter(iv)
iv = '\\x' + '\\x'.join(a+b for a,b in zip(t, t))
ivshellcode = iv + shellcode + '\\x90' * (4 - (len(shellcode)/4) % 4) + '\\x50\\x90\\x50\\x90'
ivshellcode = ivshellcode.replace('\\x', '')
blocks = []
for i in range(0, len(ivshellcode)/8):
blocks.append(int('0x'+ ivshellcode[i*8:i*8+8], 16))
for i in range(len(blocks)-1):
blocks[i+1] = (blocks[i] ^ blocks[i+1])
encoded = ""
for i in range(len(blocks)):
encoded += format(blocks[i], '08x')
return encoded
def fbxdecode(encoded):
blocks = []
cleartext = ""
for i in range(0, len(encoded)/8):
blocks.append(int('0x'+ encoded[i*8:i*8+8], 16))
for i in range(len(blocks)-1):
if (blocks[i] ^ blocks[i+1] == 0x90509050):
break
blocks[i] = (blocks[i] ^ blocks[i+1])
cleartext += format(blocks[i], '08x')
return cleartext
if (len(sys.argv) != 2):
print "Usage: ./" + sys.argv[0] + " \"<ShellCode>\""
exit()
shellcode = sys.argv[1]
if '\\' not in shellcode:
print "[!] Use need to use double quotes or single quotes in shellcode"
exit()
print "\n[Shellcode]"
print shellcode + "\n"
encoded = fbxencode(shellcode)
t = iter(encoded)
encoded_format = '0x' + ',0x'.join(a+b for a,b in zip(t, t))
while "0x00" in encoded_format:
encoded = fbxencode(shellcode)
t = iter(encoded)
encoded_format = '0x' + ',0x'.join(a+b for a,b in zip(t, t))
print "[Encoded]"
t = iter(encoded)
print '0x' + ',0x'.join(a+b for a,b in zip(t, t))
t = iter(encoded)
print '\\x' + '\\x'.join(a+b for a,b in zip(t, t)) + "\n"
decoded = fbxdecode(encoded)
t = iter(decoded)
print "[Decoded]"
print '\\x' + '\\x'.join(a+b for a,b in zip(t, t)) + "\n"