From 03136d1469d432dccaf880034d2d42b7ddb13393 Mon Sep 17 00:00:00 2001 From: Mike Auty Date: Thu, 2 Sep 2021 22:51:32 +0100 Subject: [PATCH] Automagic: Clean up the windows self-referential dtb finder --- volatility3/framework/automagic/__init__.py | 4 +- volatility3/framework/automagic/windows.py | 469 +++++++++++--------- 2 files changed, 249 insertions(+), 224 deletions(-) diff --git a/volatility3/framework/automagic/__init__.py b/volatility3/framework/automagic/__init__.py index 626126c8c..e4d422c99 100644 --- a/volatility3/framework/automagic/__init__.py +++ b/volatility3/framework/automagic/__init__.py @@ -22,7 +22,7 @@ from volatility3.framework.configuration import requirements vollog = logging.getLogger(__name__) windows_automagic = [ - 'ConstructionMagic', 'LayerStacker', 'WintelHelper', 'KernelPDBScanner', 'WinSwapLayers', 'KernelModule' + 'ConstructionMagic', 'LayerStacker', 'KernelPDBScanner', 'WinSwapLayers', 'KernelModule' ] linux_automagic = ['ConstructionMagic', 'LayerStacker', 'LinuxBannerCache', 'LinuxSymbolFinder', 'KernelModule'] @@ -46,7 +46,7 @@ def available(context: interfaces.context.ContextInterface) -> List[interfaces.a clazz(context, interfaces.configuration.path_join(config_path, clazz.__name__)) for clazz in class_subclasses(interfaces.automagic.AutomagicInterface) ], - key = lambda x: x.priority) + key = lambda x: x.priority) def choose_automagic( diff --git a/volatility3/framework/automagic/windows.py b/volatility3/framework/automagic/windows.py index 147602fac..eba79ef98 100644 --- a/volatility3/framework/automagic/windows.py +++ b/volatility3/framework/automagic/windows.py @@ -28,7 +28,7 @@ The self-referential indices for older versions of windows are listed below: """ import logging import struct -from typing import Any, Generator, List, Optional, Tuple, Type +from typing import Generator, List, Optional, Tuple, Type, Iterable from volatility3.framework import interfaces, layers, constants from volatility3.framework.configuration import requirements @@ -37,147 +37,153 @@ from volatility3.framework.layers import intel vollog = logging.getLogger(__name__) -class DtbTest: - """This class generically contains the tests for a page based on a set of - class parameters. +# class DtbTest: +# """This class generically contains the tests for a page based on a set of +# class parameters. +# +# When constructed it contains all the information necessary to +# extract a specific index from a page and determine whether it points +# back to that page's offset. +# """ +# +# def __init__(self, layer_type: Type[layers.intel.Intel], ptr_struct: str, ptr_reference: List[int], +# mask: int) -> None: +# self.layer_type = layer_type +# self.ptr_struct = ptr_struct +# self.ptr_size = struct.calcsize(ptr_struct) +# self.ptr_reference = ptr_reference +# self.mask = mask +# self.page_size: int = layer_type.page_size +# +# def _unpack(self, value: bytes) -> int: +# return struct.unpack("<" + self.ptr_struct, value)[0] +# +# def __call__(self, data: bytes, data_offset: int, page_offset: int) -> Optional[Tuple[int, Any]]: +# """Tests a specific page in a chunk of data to see if it contains a +# self-referential pointer. +# +# Args: +# data: The chunk of data that contains the page to be scanned +# data_offset: Where, within the layer, the chunk of data lives +# page_offset: Where, within the data, the page to be scanned starts +# +# Returns: +# A valid DTB within this page (and an additional parameter for data) +# """ +# for ptr_reference in self.ptr_reference: +# value = data[page_offset + (ptr_reference * self.ptr_size):page_offset + +# ((ptr_reference + 1) * self.ptr_size)] +# try: +# ptr = self._unpack(value) +# except struct.error: +# return None +# # The value *must* be present (bit 0) since it's a mapped page +# # It's almost always writable (bit 1) +# # It's occasionally Super, but not reliably so, haven't checked when/why not +# # The top 3-bits are usually ignore (which in practice means 0 +# # Need to find out why the middle 3-bits are usually 6 (0110) +# if ptr != 0 and (ptr & self.mask == data_offset + page_offset) & (ptr & 0xFF1 == 0x61): +# dtb = (ptr & self.mask) +# return self.second_pass(dtb, data, data_offset) +# return None +# +# def second_pass(self, dtb: int, data: bytes, data_offset: int) -> Optional[Tuple[int, Any]]: +# """Re-reads over the whole page to validate other records based on the +# number of pages marked user vs super. +# +# Args: +# dtb: The identified dtb that needs validating +# data: The chunk of data that contains the dtb to be validated +# data_offset: Where, within the layer, the chunk of data lives +# +# Returns: +# A valid DTB within this page +# """ +# page = data[dtb - data_offset:dtb - data_offset + self.page_size] +# usr_count, sup_count = 0, 0 +# for i in range(0, self.page_size, self.ptr_size): +# val = self._unpack(page[i:i + self.ptr_size]) +# if val & 0x1: +# sup_count += 0 if (val & 0x4) else 1 +# usr_count += 1 if (val & 0x4) else 0 +# # print(hex(dtb), usr_count, sup_count, usr_count + sup_count) +# # We sometimes find bogus DTBs at 0x16000 with a very low sup_count and 0 usr_count +# # I have a winxpsp2-x64 image with identical usr/sup counts at 0x16000 and 0x24c00 as well as the actual 0x3c3000 +# if usr_count or sup_count > 5: +# return dtb, None +# return None +# +# +# class DtbTest32bit(DtbTest): +# +# def __init__(self) -> None: +# super().__init__(layer_type = layers.intel.WindowsIntel, +# ptr_struct = "I", +# ptr_reference = [0x300], +# mask = 0xFFFFF000) +# +# +# class DtbTest64bit(DtbTest): +# +# def __init__(self) -> None: +# super().__init__(layer_type = layers.intel.WindowsIntel32e, +# ptr_struct = "Q", +# ptr_reference = range(0x1E0, 0x1FF), +# mask = 0x3FFFFFFFFFF000) +# +# # As of Windows-10 RS1+, the ptr_reference is randomized: +# # https://blahcat.github.io/2020/06/15/playing_with_self_reference_pml4_entry/ +# # So far, we've only seen examples between 0x1e0 and 0x1ff +# +# +# class DtbTestPae(DtbTest): +# +# def __init__(self) -> None: +# super().__init__(layer_type = layers.intel.WindowsIntelPAE, +# ptr_struct = "Q", +# ptr_reference = [0x3], +# mask = 0x3FFFFFFFFFF000) +# +# def second_pass(self, dtb: int, data: bytes, data_offset: int) -> Optional[Tuple[int, Any]]: +# """PAE top level directory tables contains four entries and the self- +# referential pointer occurs in the second level of tables (so as not to +# use up a full quarter of the space). This is very high in the space, +# and occurs in the fourht (last quarter) second-level table. The +# second-level tables appear always to come sequentially directly after +# the real dtb. The value for the real DTB is therefore four page +# earlier (and the fourth entry should point back to the `dtb` parameter +# this function was originally passed. +# +# Args: +# dtb: The identified self-referential pointer that needs validating +# data: The chunk of data that contains the dtb to be validated +# data_offset: Where, within the layer, the chunk of data lives +# +# Returns: +# Returns the actual DTB of the PAE space +# """ +# dtb -= 0x4000 +# # If we're not in something that the overlap would pick up +# if dtb - data_offset >= 0: +# pointers = data[dtb - data_offset + (3 * self.ptr_size):dtb - data_offset + (4 * self.ptr_size)] +# val = self._unpack(pointers) +# if (val & self.mask == dtb + 0x4000) and (val & 0xFFF == 0x001): +# return dtb, None +# return None +# - When constructed it contains all the information necessary to - extract a specific index from a page and determine whether it points - back to that page's offset. - """ - - def __init__(self, layer_type: Type[layers.intel.Intel], ptr_struct: str, ptr_reference: List[int], - mask: int) -> None: - self.layer_type = layer_type - self.ptr_struct = ptr_struct - self.ptr_size = struct.calcsize(ptr_struct) - self.ptr_reference = ptr_reference - self.mask = mask - self.page_size: int = layer_type.page_size - - def _unpack(self, value: bytes) -> int: - return struct.unpack("<" + self.ptr_struct, value)[0] - - def __call__(self, data: bytes, data_offset: int, page_offset: int) -> Optional[Tuple[int, Any]]: - """Tests a specific page in a chunk of data to see if it contains a - self-referential pointer. - - Args: - data: The chunk of data that contains the page to be scanned - data_offset: Where, within the layer, the chunk of data lives - page_offset: Where, within the data, the page to be scanned starts - - Returns: - A valid DTB within this page (and an additional parameter for data) - """ - for ptr_reference in self.ptr_reference: - value = data[page_offset + (ptr_reference * self.ptr_size):page_offset + - ((ptr_reference + 1) * self.ptr_size)] - try: - ptr = self._unpack(value) - except struct.error: - return None - # The value *must* be present (bit 0) since it's a mapped page - # It's almost always writable (bit 1) - # It's occasionally Super, but not reliably so, haven't checked when/why not - # The top 3-bits are usually ignore (which in practice means 0 - # Need to find out why the middle 3-bits are usually 6 (0110) - if ptr != 0 and (ptr & self.mask == data_offset + page_offset) & (ptr & 0xFF1 == 0x61): - dtb = (ptr & self.mask) - return self.second_pass(dtb, data, data_offset) - return None - - def second_pass(self, dtb: int, data: bytes, data_offset: int) -> Optional[Tuple[int, Any]]: - """Re-reads over the whole page to validate other records based on the - number of pages marked user vs super. - - Args: - dtb: The identified dtb that needs validating - data: The chunk of data that contains the dtb to be validated - data_offset: Where, within the layer, the chunk of data lives - - Returns: - A valid DTB within this page - """ - page = data[dtb - data_offset:dtb - data_offset + self.page_size] - usr_count, sup_count = 0, 0 - for i in range(0, self.page_size, self.ptr_size): - val = self._unpack(page[i:i + self.ptr_size]) - if val & 0x1: - sup_count += 0 if (val & 0x4) else 1 - usr_count += 1 if (val & 0x4) else 0 - # print(hex(dtb), usr_count, sup_count, usr_count + sup_count) - # We sometimes find bogus DTBs at 0x16000 with a very low sup_count and 0 usr_count - # I have a winxpsp2-x64 image with identical usr/sup counts at 0x16000 and 0x24c00 as well as the actual 0x3c3000 - if usr_count or sup_count > 5: - return dtb, None - return None - - -class DtbTest32bit(DtbTest): - - def __init__(self) -> None: - super().__init__(layer_type = layers.intel.WindowsIntel, - ptr_struct = "I", - ptr_reference = [0x300], - mask = 0xFFFFF000) - - -class DtbTest64bit(DtbTest): - - def __init__(self) -> None: - super().__init__(layer_type = layers.intel.WindowsIntel32e, - ptr_struct = "Q", - ptr_reference = range(0x1E0, 0x1FF), - mask = 0x3FFFFFFFFFF000) - - # As of Windows-10 RS1+, the ptr_reference is randomized: - # https://blahcat.github.io/2020/06/15/playing_with_self_reference_pml4_entry/ - # So far, we've only seen examples between 0x1e0 and 0x1ff - - -class DtbTestPae(DtbTest): - - def __init__(self) -> None: - super().__init__(layer_type = layers.intel.WindowsIntelPAE, - ptr_struct = "Q", - ptr_reference = [0x3], - mask = 0x3FFFFFFFFFF000) - - def second_pass(self, dtb: int, data: bytes, data_offset: int) -> Optional[Tuple[int, Any]]: - """PAE top level directory tables contains four entries and the self- - referential pointer occurs in the second level of tables (so as not to - use up a full quarter of the space). This is very high in the space, - and occurs in the fourht (last quarter) second-level table. The - second-level tables appear always to come sequentially directly after - the real dtb. The value for the real DTB is therefore four page - earlier (and the fourth entry should point back to the `dtb` parameter - this function was originally passed. - - Args: - dtb: The identified self-referential pointer that needs validating - data: The chunk of data that contains the dtb to be validated - data_offset: Where, within the layer, the chunk of data lives - - Returns: - Returns the actual DTB of the PAE space - """ - dtb -= 0x4000 - # If we're not in something that the overlap would pick up - if dtb - data_offset >= 0: - pointers = data[dtb - data_offset + (3 * self.ptr_size):dtb - data_offset + (4 * self.ptr_size)] - val = self._unpack(pointers) - if (val & self.mask == dtb + 0x4000) and (val & 0xFFF == 0x001): - return dtb, None - return None - - -class DtbSelfReferential(DtbTest): +class DtbSelfReferential: """A generic DTB test which looks for a self-referential pointer at *any* index within the page.""" - def __init__(self, layer_type: Type[layers.intel.Intel], ptr_struct: str, ptr_reference: int, mask: int) -> None: - super().__init__(layer_type = layer_type, ptr_struct = ptr_struct, ptr_reference = ptr_reference, mask = mask) + def __init__(self, layer_type: Type[layers.intel.Intel], ptr_struct: str, mask: int, + valid_range: Iterable[int]) -> None: + self.layer_type = layer_type + self.ptr_struct = ptr_struct + self.ptr_size = struct.calcsize(ptr_struct) + self.mask = mask + self.page_size: int = layer_type.page_size + self.valid_range = valid_range def __call__(self, data: bytes, data_offset: int, page_offset: int) -> Optional[Tuple[int, int]]: page = data[page_offset:page_offset + self.page_size] @@ -192,7 +198,9 @@ class DtbSelfReferential(DtbTest): ref_pages.add(ref) # The DTB is extremely unlikely to refer back to itself. so the number of reference should always be exactly 1 if len(ref_pages) == 1: - return (data_offset + page_offset), ref_pages.pop() + ref_page = ref_pages.pop() + if (ref_page // self.ptr_size) in self.valid_range: + return (data_offset + page_offset), ref_page return None @@ -201,8 +209,8 @@ class DtbSelfRef32bit(DtbSelfReferential): def __init__(self): super().__init__(layer_type = layers.intel.WindowsIntel, ptr_struct = "I", - ptr_reference = 0x300, - mask = 0xFFFFF000) + mask = 0xFFFFF000, + valid_range = [0x300]) class DtbSelfRef64bit(DtbSelfReferential): @@ -210,23 +218,39 @@ class DtbSelfRef64bit(DtbSelfReferential): def __init__(self) -> None: super().__init__(layer_type = layers.intel.WindowsIntel32e, ptr_struct = "Q", - ptr_reference = 0x1ED, + mask = 0x3FFFFFFFFFF000, + valid_range = range(0x100, 0x1ff)) + + +class DtbSelfRefPae(DtbSelfReferential): + + def __init__(self) -> None: + super().__init__(layer_type = layers.intel.WindowsIntelPAE, + ptr_struct = "Q", + valid_range = [0x3], mask = 0x3FFFFFFFFFF000) + def __call__(self, *args, **kwargs): + dtb = super().__call__(*args, **kwargs) + if dtb: + return dtb[0] - 0x4000, dtb[1] + return dtb + class PageMapScanner(interfaces.layers.ScannerInterface): """Scans through all pages using DTB tests to determine a dtb offset and architecture.""" overlap = 0x4000 thread_safe = True - tests = [DtbTest64bit(), DtbTest32bit(), DtbTestPae()] + tests = [DtbSelfRef64bit(), DtbSelfRefPae(), DtbSelfRef32bit()] """The default tests to run when searching for DTBs""" - def __init__(self, tests: List[DtbTest]) -> None: + def __init__(self, tests: Optional[List[DtbSelfReferential]]) -> None: super().__init__() - self.tests = tests + if tests: + self.tests = tests - def __call__(self, data: bytes, data_offset: int) -> Generator[Tuple[DtbTest, int], None, None]: + def __call__(self, data: bytes, data_offset: int) -> Generator[Tuple[DtbSelfReferential, int], None, None]: for test in self.tests: for page_offset in range(0, len(data), 0x1000): result = test(data, data_offset, page_offset) @@ -234,61 +258,61 @@ class PageMapScanner(interfaces.layers.ScannerInterface): yield (test, result[0]) -class WintelHelper(interfaces.automagic.AutomagicInterface): - """Windows DTB finder based on self-referential pointers. - - This class adheres to the :class:`~volatility3.framework.interfaces.automagic.AutomagicInterface` interface - and both determines the directory table base of an intel layer if one hasn't been specified, and constructs - the intel layer if necessary (for example when reconstructing a pre-existing configuration). - - It will scan for existing TranslationLayers that do not have a DTB using the :class:`PageMapScanner` - """ - priority = 20 - tests = [DtbTest64bit(), DtbTest32bit(), DtbTestPae()] - - def __call__(self, - context: interfaces.context.ContextInterface, - config_path: str, - requirement: interfaces.configuration.RequirementInterface, - progress_callback: constants.ProgressCallback = None) -> None: - useful = [] - sub_config_path = interfaces.configuration.path_join(config_path, requirement.name) - if (isinstance(requirement, requirements.TranslationLayerRequirement) - and requirement.requirements.get("class", False) and requirement.unsatisfied(context, config_path)): - class_req = requirement.requirements["class"] - - for test in self.tests: - if (test.layer_type.__module__ + "." + test.layer_type.__name__ == class_req.config_value( - context, sub_config_path)): - useful.append(test) - - # Determine if a class has been chosen - # Once an appropriate class has been chosen, attempt to determine the page_map_offset value - if ("memory_layer" in requirement.requirements - and not requirement.requirements["memory_layer"].unsatisfied(context, sub_config_path)): - # Only bother getting the DTB if we don't already have one - page_map_offset_path = interfaces.configuration.path_join(sub_config_path, "page_map_offset") - if not context.config.get(page_map_offset_path, None): - physical_layer_name = requirement.requirements["memory_layer"].config_value( - context, sub_config_path) - if not isinstance(physical_layer_name, str): - raise TypeError(f"Physical layer name is not a string: {sub_config_path}") - physical_layer = context.layers[physical_layer_name] - # Check lower layer metadata first - if physical_layer.metadata.get('page_map_offset', None): - context.config[page_map_offset_path] = physical_layer.metadata['page_map_offset'] - else: - hits = physical_layer.scan(context, PageMapScanner(useful), progress_callback) - for test, dtb in hits: - context.config[page_map_offset_path] = dtb - break - else: - return None - if isinstance(requirement, interfaces.configuration.ConstructableRequirementInterface): - requirement.construct(context, config_path) - else: - for subreq in requirement.requirements.values(): - self(context, sub_config_path, subreq) +# class WintelHelper(interfaces.automagic.AutomagicInterface): +# """Windows DTB finder based on self-referential pointers. +# +# This class adheres to the :class:`~volatility3.framework.interfaces.automagic.AutomagicInterface` interface +# and both determines the directory table base of an intel layer if one hasn't been specified, and constructs +# the intel layer if necessary (for example when reconstructing a pre-existing configuration). +# +# It will scan for existing TranslationLayers that do not have a DTB using the :class:`PageMapScanner` +# """ +# priority = 20 +# tests = [DtbTest64bit(), DtbTest32bit(), DtbTestPae()] +# +# def __call__(self, +# context: interfaces.context.ContextInterface, +# config_path: str, +# requirement: interfaces.configuration.RequirementInterface, +# progress_callback: constants.ProgressCallback = None) -> None: +# useful = [] +# sub_config_path = interfaces.configuration.path_join(config_path, requirement.name) +# if (isinstance(requirement, requirements.TranslationLayerRequirement) +# and requirement.requirements.get("class", False) and requirement.unsatisfied(context, config_path)): +# class_req = requirement.requirements["class"] +# +# for test in self.tests: +# if (test.layer_type.__module__ + "." + test.layer_type.__name__ == class_req.config_value( +# context, sub_config_path)): +# useful.append(test) +# +# # Determine if a class has been chosen +# # Once an appropriate class has been chosen, attempt to determine the page_map_offset value +# if ("memory_layer" in requirement.requirements +# and not requirement.requirements["memory_layer"].unsatisfied(context, sub_config_path)): +# # Only bother getting the DTB if we don't already have one +# page_map_offset_path = interfaces.configuration.path_join(sub_config_path, "page_map_offset") +# if not context.config.get(page_map_offset_path, None): +# physical_layer_name = requirement.requirements["memory_layer"].config_value( +# context, sub_config_path) +# if not isinstance(physical_layer_name, str): +# raise TypeError(f"Physical layer name is not a string: {sub_config_path}") +# physical_layer = context.layers[physical_layer_name] +# # Check lower layer metadata first +# if physical_layer.metadata.get('page_map_offset', None): +# context.config[page_map_offset_path] = physical_layer.metadata['page_map_offset'] +# else: +# hits = physical_layer.scan(context, PageMapScanner(useful), progress_callback) +# for test, dtb in hits: +# context.config[page_map_offset_path] = dtb +# break +# else: +# return None +# if isinstance(requirement, interfaces.configuration.ConstructableRequirementInterface): +# requirement.construct(context, config_path) +# else: +# for subreq in requirement.requirements.values(): +# self(context, sub_config_path, subreq) class WindowsIntelStacker(interfaces.automagic.StackerLayerInterface): @@ -338,29 +362,30 @@ class WindowsIntelStacker(interfaces.automagic.StackerLayerInterface): config_path, "page_map_offset")] = base_layer.metadata['page_map_offset'] layer = layer_type(context, config_path = config_path, name = new_layer_name, metadata = {'os': 'Windows'}) - # Check for the self-referential pointer - if layer is None: - hits = base_layer.scan(context, PageMapScanner(WintelHelper.tests), progress_callback = progress_callback) - layer = None - config_path = None - for test, dtb in hits: - new_layer_name = context.layers.free_layer_name("IntelLayer") - config_path = interfaces.configuration.path_join("IntelHelper", new_layer_name) - context.config[interfaces.configuration.path_join(config_path, "memory_layer")] = layer_name - context.config[interfaces.configuration.path_join(config_path, "page_map_offset")] = dtb - layer = test.layer_type(context, - config_path = config_path, - name = new_layer_name, - metadata = {'os': 'Windows'}) - break + # # Check for the self-referential pointer + # if layer is None: + # hits = base_layer.scan(context, PageMapScanner(), progress_callback = progress_callback) + # layer = None + # config_path = None + # for test, dtb in hits: + # new_layer_name = context.layers.free_layer_name("IntelLayer") + # config_path = interfaces.configuration.path_join("IntelHelper", new_layer_name) + # context.config[interfaces.configuration.path_join(config_path, "memory_layer")] = layer_name + # context.config[interfaces.configuration.path_join(config_path, "page_map_offset")] = dtb + # layer = test.layer_type(context, + # config_path = config_path, + # name = new_layer_name, + # metadata = {'os': 'Windows'}) + # break # Fall back to a heuristic for finding the Windows DTB if layer is None: vollog.debug("Self-referential pointer not in well-known location, moving to recent windows heuristic") # There is a very high chance that the DTB will live in this narrow segment, assuming we couldn't find it previously hits = context.layers[layer_name].scan(context, - PageMapScanner([DtbSelfRef64bit()]), - sections = [(0x1a0000, 0x50000)], + PageMapScanner( + [DtbSelfRef64bit(), DtbSelfRefPae(), DtbSelfRef32bit()]), + sections = [(0x1a0000, 0x550000)], progress_callback = progress_callback) # Flatten the generator hits = list(hits) @@ -372,10 +397,10 @@ class WindowsIntelStacker(interfaces.automagic.StackerLayerInterface): context.config[interfaces.configuration.path_join(config_path, "memory_layer")] = layer_name context.config[interfaces.configuration.path_join(config_path, "page_map_offset")] = page_map_offset # TODO: Need to determine the layer type (chances are high it's x64, hence this default) - layer = layers.intel.WindowsIntel32e(context, - config_path = config_path, - name = new_layer_name, - metadata = {'os': 'Windows'}) + layer = test.layer_type(context, + config_path = config_path, + name = new_layer_name, + metadata = {'os': 'Windows'}) if layer is not None and config_path: vollog.debug("DTB was found at: 0x{:0x}".format(context.config[interfaces.configuration.path_join( config_path, "page_map_offset")]))