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https://github.com/cea-sec/miasm
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Ajax
68 lines
1.9 KiB
Python
68 lines
1.9 KiB
Python
from miasm2.core.bin_stream import bin_stream_str
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from miasm2.core.asmblock import AsmConstraint
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from miasm2.arch.x86.disasm import dis_x86_32, cb_x86_funcs
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def cb_x86_callpop(cur_bloc, loc_db, *args, **kwargs):
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"""
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1000: call 1005
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1005: pop
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Will give:
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1000: push 1005
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1005: pop
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"""
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# Pattern matching
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if len(cur_bloc.lines) < 1:
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return
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## We want to match a CALL, always the last line of a basic block
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last_instr = cur_bloc.lines[-1]
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if last_instr.name != 'CALL':
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return
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## The destination must be a location
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dst = last_instr.args[0]
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if not dst.is_loc():
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return
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loc_key = dst.loc_key
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offset = loc_db.get_location_offset(loc_key)
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## The destination must be the next instruction
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if offset != last_instr.offset + last_instr.l:
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return
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# Update instruction instance
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last_instr.name = 'PUSH'
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# Update next blocks to process in the disassembly engine
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cur_bloc.bto.clear()
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cur_bloc.add_cst(loc_key, AsmConstraint.c_next)
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# Prepare a tiny shellcode
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shellcode = ''.join(["\xe8\x00\x00\x00\x00", # CALL $
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"X", # POP EAX
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"\xc3", # RET
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])
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bin_stream = bin_stream_str(shellcode)
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mdis = dis_x86_32(bin_stream)
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print "Without callback:\n"
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asmcfg = mdis.dis_multiblock(0)
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print "\n".join(str(block) for block in asmcfg.blocks)
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# Enable callback
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cb_x86_funcs.append(cb_x86_callpop)
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## Other method:
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## mdis.dis_block_callback = cb_x86_callpop
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print "=" * 40
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print "With callback:\n"
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asmcfg_after = mdis.dis_multiblock(0)
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print "\n".join(str(block) for block in asmcfg_after.blocks)
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# Ensure the callback has been called
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assert asmcfg.loc_key_to_block(asmcfg.heads()[0]).lines[0].name == "CALL"
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assert asmcfg_after.loc_key_to_block(asmcfg_after.heads()[0]).lines[0].name == "PUSH"
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