49 lines
1.6 KiB
Ruby
49 lines
1.6 KiB
Ruby
##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Encoder::Xor
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def initialize
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super(
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'Name' => 'XOR Encoder',
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'Description' => 'An x64 XOR encoder. Uses an 8 byte key and takes advantage of x64 relative addressing.',
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'Author' => [ 'sf' ],
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'Arch' => ARCH_X64,
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'License' => MSF_LICENSE,
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'Decoder' =>
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{
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'KeySize' => 8,
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'KeyPack' => 'Q',
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'BlockSize' => 8,
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}
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)
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end
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# Indicate that this module can preserve some registers
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# ...which is currently not true. This is a temp fix
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# until the full preserve_registers functionality is
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# implemented.
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def can_preserve_registers?
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true
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end
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def decoder_stub( state )
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# calculate the (negative) block count . We should check this against state.badchars.
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block_count = [-( ( (state.buf.length - 1) / state.decoder_key_size) + 1)].pack( "V" )
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decoder = "\x48\x31\xC9" + # xor rcx, rcx
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"\x48\x81\xE9" + block_count + # sub ecx, block_count
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"\x48\x8D\x05\xEF\xFF\xFF\xFF" + # lea rax, [rel 0x0]
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"\x48\xBBXXXXXXXX" + # mov rbx, 0x????????????????
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"\x48\x31\x58\x27" + # xor [rax+0x27], rbx
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"\x48\x2D\xF8\xFF\xFF\xFF" + # sub rax, -8
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"\xE2\xF4" # loop 0x1B
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state.decoder_key_offset = decoder.index( 'XXXXXXXX' )
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return decoder
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end
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end
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