55 lines
1.7 KiB
Python
55 lines
1.7 KiB
Python
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from pathlib import Path
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def u16(data, off):
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return data[off] | (data[off + 1] << 8)
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def u32(data, off):
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return u16(data, off) | (u16(data, off + 2) << 16)
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def get_segment(data, selector):
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ne_off = u32(data, 0x3C)
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seg_table_off = ne_off + u16(data, ne_off + 0x22)
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align_shift = u16(data, ne_off + 0x32)
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seg_index = ((selector - 0x1000) // 8) + 1
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seg_entry_off = seg_table_off + (seg_index - 1) * 8
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sector = u16(data, seg_entry_off)
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seg_len = u16(data, seg_entry_off + 2)
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if seg_len == 0:
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seg_len = 0x10000
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seg_file_off = sector << align_shift
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return seg_file_off, seg_len
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def emit_runs(blob, seg_base, selector, allowed, minimum):
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start = None
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for i, byte in enumerate(blob):
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if byte in allowed:
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if start is None:
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start = i
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elif start is not None:
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length = i - start
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if length >= minimum:
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print(f'{selector:04X}:{start:04X} file=0x{seg_base + start:X} len=0x{length:X} bytes={blob[start:start+min(length,16)].hex(" ")}')
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start = None
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if start is not None:
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length = len(blob) - start
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if length >= minimum:
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print(f'{selector:04X}:{start:04X} file=0x{seg_base + start:X} len=0x{length:X} bytes={blob[start:start+min(length,16)].hex(" ")}')
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def main():
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data = Path(r'd:\Ghidra\Crusader\REGRET.EXE').read_bytes()
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seg_base, seg_len = get_segment(data, 0x13F8)
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blob = data[seg_base:seg_base + seg_len]
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print(f'segment 13F8 file=0x{seg_base:X} len=0x{seg_len:X}')
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print('zero runs >= 0x20')
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emit_runs(blob, seg_base, 0x13F8, {0x00}, 0x20)
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print('nop/int3 runs >= 0x10')
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emit_runs(blob, seg_base, 0x13F8, {0x90, 0xCC}, 0x10)
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if __name__ == '__main__':
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main()
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