support negative offset features (and add IDA tests) #208
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williballenthin
commented
Jul 27, 2020
| @@ -144,12 +144,13 @@ def extract_insn_offset_features(f, bb, insn): | |||
| continue | |||
| p_info = capa.features.extractors.ida.helpers.get_op_phrase_info(op) | |||
| op_off = p_info.get("offset", 0) | |||
| if 0 == op_off: | |||
| continue | |||
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for consistency with the viv extractor, we support offset=0x0.
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| if idaapi.is_mapped(op_off): | ||
| # Ignore: | ||
| # mov esi, dword_1005B148[esi] | ||
| continue | ||
|
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| op_off = capa.features.extractors.helpers.twos_complement(op_off, 32) |
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What about 8 and 16?
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i got the impression that IDA returns the offset as twos complement in a u32, never as u8/u16/u64. if this is wrong, i'd very much like to fix it.
according to some sources, like here, there is no 64-bit offset/displacement.
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| # some versions of IDA return a truncated version of the MD5. | ||
| # https://github.com/idapython/bin/issues/11 | ||
| found = idautils.GetInputFileMD5().rstrip(b"\x00").decode("ascii").lower() |
mr-tz
approved these changes
Jul 27, 2020
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codifies our decision to support offset features with negative values #197 by relaxing the lint and updating the IDA extractor.
in order to demonstrate that the IDA changes work, i implemented tests for the IDA extractor. these will not run during CI, but we can invoke them manually during development. they should be run with the
mimikatz.exe_database open.closes #197
closes #202