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Merge pull request #1770 from mandiant/backend-ghidra
ghidra: add Ghidra feature extractor and supporting code
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,152 @@ | ||
| # Copyright (C) 2023 Mandiant, Inc. All Rights Reserved. | ||
| # Licensed under the Apache License, Version 2.0 (the "License"); | ||
| # you may not use this file except in compliance with the License. | ||
| # You may obtain a copy of the License at: [package root]/LICENSE.txt | ||
| # Unless required by applicable law or agreed to in writing, software distributed under the License | ||
| # is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| # See the License for the specific language governing permissions and limitations under the License. | ||
|
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||
| import string | ||
| import struct | ||
| from typing import Tuple, Iterator | ||
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| import ghidra | ||
| from ghidra.program.model.lang import OperandType | ||
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| import capa.features.extractors.ghidra.helpers | ||
| from capa.features.common import Feature, Characteristic | ||
| from capa.features.address import Address | ||
| from capa.features.basicblock import BasicBlock | ||
| from capa.features.extractors.helpers import MIN_STACKSTRING_LEN | ||
| from capa.features.extractors.base_extractor import BBHandle, FunctionHandle | ||
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| def get_printable_len(op: ghidra.program.model.scalar.Scalar) -> int: | ||
| """Return string length if all operand bytes are ascii or utf16-le printable""" | ||
| op_bit_len = op.bitLength() | ||
| op_byte_len = op_bit_len // 8 | ||
| op_val = op.getValue() | ||
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| if op_bit_len == 8: | ||
| chars = struct.pack("<B", op_val & 0xFF) | ||
| elif op_bit_len == 16: | ||
| chars = struct.pack("<H", op_val & 0xFFFF) | ||
| elif op_bit_len == 32: | ||
| chars = struct.pack("<I", op_val & 0xFFFFFFFF) | ||
| elif op_bit_len == 64: | ||
| chars = struct.pack("<Q", op_val & 0xFFFFFFFFFFFFFFFF) | ||
| else: | ||
| raise ValueError(f"Unhandled operand data type 0x{op_bit_len:x}.") | ||
|
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| def is_printable_ascii(chars_: bytes): | ||
| return all(c < 127 and chr(c) in string.printable for c in chars_) | ||
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| def is_printable_utf16le(chars_: bytes): | ||
| if all(c == 0x00 for c in chars_[1::2]): | ||
| return is_printable_ascii(chars_[::2]) | ||
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| if is_printable_ascii(chars): | ||
| return op_byte_len | ||
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| if is_printable_utf16le(chars): | ||
| return op_byte_len | ||
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| return 0 | ||
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| def is_mov_imm_to_stack(insn: ghidra.program.database.code.InstructionDB) -> bool: | ||
| """verify instruction moves immediate onto stack""" | ||
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| # Ghidra will Bitwise OR the OperandTypes to assign multiple | ||
| # i.e., the first operand is a stackvar (dynamically allocated), | ||
| # and the second is a scalar value (single int/char/float/etc.) | ||
| mov_its_ops = [(OperandType.ADDRESS | OperandType.DYNAMIC), OperandType.SCALAR] | ||
| found = False | ||
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| # MOV dword ptr [EBP + local_*], 0x65 | ||
| if insn.getMnemonicString().startswith("MOV"): | ||
| found = all(insn.getOperandType(i) == mov_its_ops[i] for i in range(2)) | ||
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| return found | ||
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| def bb_contains_stackstring(bb: ghidra.program.model.block.CodeBlock) -> bool: | ||
| """check basic block for stackstring indicators | ||
| true if basic block contains enough moves of constant bytes to the stack | ||
| """ | ||
| count = 0 | ||
| for insn in currentProgram().getListing().getInstructions(bb, True): # type: ignore [name-defined] # noqa: F821 | ||
| if is_mov_imm_to_stack(insn): | ||
| count += get_printable_len(insn.getScalar(1)) | ||
| if count > MIN_STACKSTRING_LEN: | ||
| return True | ||
| return False | ||
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| def _bb_has_tight_loop(bb: ghidra.program.model.block.CodeBlock): | ||
| """ | ||
| parse tight loops, true if last instruction in basic block branches to bb start | ||
| """ | ||
| # Reverse Ordered, first InstructionDB | ||
| last_insn = currentProgram().getListing().getInstructions(bb, False).next() # type: ignore [name-defined] # noqa: F821 | ||
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| if last_insn.getFlowType().isJump(): | ||
| return last_insn.getAddress(0) == bb.getMinAddress() | ||
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| return False | ||
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| def extract_bb_stackstring(fh: FunctionHandle, bbh: BBHandle) -> Iterator[Tuple[Feature, Address]]: | ||
| """extract stackstring indicators from basic block""" | ||
| bb: ghidra.program.model.block.CodeBlock = bbh.inner | ||
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| if bb_contains_stackstring(bb): | ||
| yield Characteristic("stack string"), bbh.address | ||
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| def extract_bb_tight_loop(fh: FunctionHandle, bbh: BBHandle) -> Iterator[Tuple[Feature, Address]]: | ||
| """check basic block for tight loop indicators""" | ||
| bb: ghidra.program.model.block.CodeBlock = bbh.inner | ||
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| if _bb_has_tight_loop(bb): | ||
| yield Characteristic("tight loop"), bbh.address | ||
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| BASIC_BLOCK_HANDLERS = ( | ||
| extract_bb_tight_loop, | ||
| extract_bb_stackstring, | ||
| ) | ||
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| def extract_features(fh: FunctionHandle, bbh: BBHandle) -> Iterator[Tuple[Feature, Address]]: | ||
| """ | ||
| extract features from the given basic block. | ||
| args: | ||
| bb: the basic block to process. | ||
| yields: | ||
| Tuple[Feature, int]: the features and their location found in this basic block. | ||
| """ | ||
| yield BasicBlock(), bbh.address | ||
| for bb_handler in BASIC_BLOCK_HANDLERS: | ||
| for feature, addr in bb_handler(fh, bbh): | ||
| yield feature, addr | ||
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| def main(): | ||
| features = [] | ||
| from capa.features.extractors.ghidra.extractor import GhidraFeatureExtractor | ||
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| for fh in GhidraFeatureExtractor().get_functions(): | ||
| for bbh in capa.features.extractors.ghidra.helpers.get_function_blocks(fh): | ||
| features.extend(list(extract_features(fh, bbh))) | ||
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| import pprint | ||
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| pprint.pprint(features) # noqa: T203 | ||
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| if __name__ == "__main__": | ||
| main() |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,75 @@ | ||
| # Copyright (C) 2023 Mandiant, Inc. All Rights Reserved. | ||
| # Licensed under the Apache License, Version 2.0 (the "License"); | ||
| # you may not use this file except in compliance with the License. | ||
| # You may obtain a copy of the License at: [package root]/LICENSE.txt | ||
| # Unless required by applicable law or agreed to in writing, software distributed under the License | ||
| # is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| # See the License for the specific language governing permissions and limitations under the License. | ||
| from typing import List, Tuple, Iterator | ||
|
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| import capa.features.extractors.ghidra.file | ||
| import capa.features.extractors.ghidra.insn | ||
| import capa.features.extractors.ghidra.global_ | ||
| import capa.features.extractors.ghidra.function | ||
| import capa.features.extractors.ghidra.basicblock | ||
| from capa.features.common import Feature | ||
| from capa.features.address import Address, AbsoluteVirtualAddress | ||
| from capa.features.extractors.base_extractor import BBHandle, InsnHandle, FunctionHandle, FeatureExtractor | ||
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| class GhidraFeatureExtractor(FeatureExtractor): | ||
| def __init__(self): | ||
| super().__init__() | ||
| import capa.features.extractors.ghidra.helpers as ghidra_helpers | ||
|
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| self.global_features: List[Tuple[Feature, Address]] = [] | ||
| self.global_features.extend(capa.features.extractors.ghidra.file.extract_file_format()) | ||
| self.global_features.extend(capa.features.extractors.ghidra.global_.extract_os()) | ||
| self.global_features.extend(capa.features.extractors.ghidra.global_.extract_arch()) | ||
| self.imports = ghidra_helpers.get_file_imports() | ||
| self.externs = ghidra_helpers.get_file_externs() | ||
| self.fakes = ghidra_helpers.map_fake_import_addrs() | ||
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| def get_base_address(self): | ||
| return AbsoluteVirtualAddress(currentProgram().getImageBase().getOffset()) # type: ignore [name-defined] # noqa: F821 | ||
|
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| def extract_global_features(self): | ||
| yield from self.global_features | ||
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| def extract_file_features(self): | ||
| yield from capa.features.extractors.ghidra.file.extract_features() | ||
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| def get_functions(self) -> Iterator[FunctionHandle]: | ||
| import capa.features.extractors.ghidra.helpers as ghidra_helpers | ||
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| for fhandle in ghidra_helpers.get_function_symbols(): | ||
| fh: FunctionHandle = FunctionHandle( | ||
| address=AbsoluteVirtualAddress(fhandle.getEntryPoint().getOffset()), | ||
| inner=fhandle, | ||
| ctx={"imports_cache": self.imports, "externs_cache": self.externs, "fakes_cache": self.fakes}, | ||
| ) | ||
| yield fh | ||
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| @staticmethod | ||
| def get_function(addr: int) -> FunctionHandle: | ||
| func = getFunctionContaining(toAddr(addr)) # type: ignore [name-defined] # noqa: F821 | ||
| return FunctionHandle(address=AbsoluteVirtualAddress(func.getEntryPoint().getOffset()), inner=func) | ||
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| def extract_function_features(self, fh: FunctionHandle) -> Iterator[Tuple[Feature, Address]]: | ||
| yield from capa.features.extractors.ghidra.function.extract_features(fh) | ||
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| def get_basic_blocks(self, fh: FunctionHandle) -> Iterator[BBHandle]: | ||
| import capa.features.extractors.ghidra.helpers as ghidra_helpers | ||
|
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| yield from ghidra_helpers.get_function_blocks(fh) | ||
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| def extract_basic_block_features(self, fh: FunctionHandle, bbh: BBHandle) -> Iterator[Tuple[Feature, Address]]: | ||
| yield from capa.features.extractors.ghidra.basicblock.extract_features(fh, bbh) | ||
|
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| def get_instructions(self, fh: FunctionHandle, bbh: BBHandle) -> Iterator[InsnHandle]: | ||
| import capa.features.extractors.ghidra.helpers as ghidra_helpers | ||
|
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| yield from ghidra_helpers.get_insn_in_range(bbh) | ||
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| def extract_insn_features(self, fh: FunctionHandle, bbh: BBHandle, ih: InsnHandle): | ||
| yield from capa.features.extractors.ghidra.insn.extract_features(fh, bbh, ih) |
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