Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
ASPack-2.29 Unpacker
#
# ASPack 2.29 unpacker via. Dynamic Analysis
#
$:.unshift("C:\\Lib\\metasm")
require 'metasm'
AS229_OEP_PUSH_OFFSET = 0x420
def _msg(m, error = false)
if error
$stderr.puts("[-] #{m}")
else
$stdout.puts("[+] #{m}")
end
end
def as229_unpack(inexe, outexe)
_msg("Trying to get debug privilege")
Metasm::WinOS.get_debug_privilege
pe = Metasm::PE.decode_file(inexe)
aspack_sec = pe.sections.find {|s| s.name == ".aspack"}
if aspack_sec.nil?
_msg("Failed to find .aspack section (not ASPack protected??)", true)
return
end
_msg("Starting #{inexe} in debug mode")
dbg = Metasm::OS.current.create_process(inexe).debugger()
pe_base = pe.optheader.image_base # TODO: Get it from PEB
dbg.bpx(pe_base + pe.optheader.entrypoint, true) do
_msg("Breakpoint hit: aspack!EP")
dbg.bpx(pe.optheader.image_base + aspack_sec.virtaddr + AS229_OEP_PUSH_OFFSET, true) do
_msg("Breakpoint hit: OEP call")
if dbg.memory[dbg.get_reg_value(:eip), 1].unpack('C').first() != 0x68
_msg("Unexpected instruction at OEP call (was expecting 'push'")
dbg.kill
return
end
oep_addr = dbg.memory[dbg.get_reg_value(:eip) + 1, 4].unpack('V').first()
_msg("OEP address: 0x%08x" % [oep_addr])
_msg("Trying to dump PE")
pe_dump = Metasm::LoadedPE.memdump(dbg.memory, pe_base, oep_addr)
#pe_dump.sections.delete_if {|sec| ['.aspack', '.asdata'].include? sec.name }
# TODO: rebuild IAT
pe_dump.encode_file(outexe)
_msg("Terminating debugger")
dbg.kill
end
end
_msg("Executing")
begin
dbg.run_forever
rescue Interrupt
dbg.kill
end
end
if __FILE__ == $0
as229_unpack(ARGV.shift, ARGV.shift) # packed.exe, unpacked.exe
end
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.