diff --git a/volatility3/framework/plugins/windows/hollowprocesses.py b/volatility3/framework/plugins/windows/hollowprocesses.py new file mode 100644 index 000000000..69fa94f06 --- /dev/null +++ b/volatility3/framework/plugins/windows/hollowprocesses.py @@ -0,0 +1,237 @@ +# This file is Copyright 2024 Volatility Foundation and licensed under the Volatility Software License 1.0 +# which is available at https://www.volatilityfoundation.org/license/vsl-v1.0 +# +import logging +from typing import NamedTuple, Dict, Generator + +from volatility3.framework import interfaces, exceptions, constants +from volatility3.framework import renderers +from volatility3.framework.configuration import requirements +from volatility3.framework.objects import utility +from volatility3.plugins.windows import pslist, vadinfo + +vollog = logging.getLogger(__name__) + +VadData = NamedTuple( + "VadData", + [ + ("protection", str), + ("path", str), + ], +) + +DLLData = NamedTuple( + "DLLData", + [ + ("path", str), + ], +) + +### Useful references on process hollowing +# https://cysinfo.com/detecting-deceptive-hollowing-techniques/ +# https://github.com/m0n0ph1/Process-Hollowing + + +class HollowProcesses(interfaces.plugins.PluginInterface): + """Lists hollowed processes""" + + _required_framework_version = (2, 4, 0) + + @classmethod + def get_requirements(cls): + # Since we're calling the plugin, make sure we have the plugin's requirements + return [ + requirements.ModuleRequirement( + name="kernel", + description="Windows kernel", + architectures=["Intel32", "Intel64"], + ), + requirements.ListRequirement( + name="pid", + element_type=int, + description="Process IDs to include (all other processes are excluded)", + optional=True, + ), + requirements.VersionRequirement( + name="pslist", component=pslist.PsList, version=(2, 0, 0) + ), + requirements.VersionRequirement( + name="vadinfo", component=vadinfo.VadInfo, version=(2, 0, 0) + ), + ] + + def _get_vads_data( + self, proc: interfaces.objects.ObjectInterface + ) -> Dict[int, VadData]: + """ + Returns a dictionary of: + base address -> (protection string, file name) + For each mapped VAD in the process. This is used + for quick lookups of data and matching the DLL + at the same base address as the VAD + """ + vads = {} + + kernel = self.context.modules[self.config["kernel"]] + + for vad in proc.get_vad_root().traverse(): + protection_string = vad.get_protection( + vadinfo.VadInfo.protect_values( + self.context, kernel.layer_name, kernel.symbol_table_name + ), + vadinfo.winnt_protections, + ) + + fn = vad.get_file_name() + if not fn or not isinstance(fn, str): + fn = "" + + vads[vad.get_start()] = VadData(protection_string, fn) + + return vads + + def _get_dlls_map( + self, proc: interfaces.objects.ObjectInterface + ) -> Dict[int, DLLData]: + """ + Returns a dictionary of: + base address -> path + for each DLL loaded in the process + + This is used to cross compare with + the corresponding VAD and to have a + backup path source in case of smear + in the VAD + """ + dlls = {} + + for entry in proc.load_order_modules(): + try: + base = entry.DllBase + except exceptions.InvalidAddressException: + continue + + try: + FullDllName = entry.FullDllName.get_string() + except exceptions.InvalidAddressException: + FullDllName = renderers.UnreadableValue() + + dlls[base] = DLLData(FullDllName) + + return dlls + + def _get_image_base(self, proc: interfaces.objects.ObjectInterface) -> int: + """ + Uses the PEB to get the image base of the process + """ + kernel = self.context.modules[self.config["kernel"]] + + try: + proc_layer_name = proc.add_process_layer() + peb = self.context.object( + kernel.symbol_table_name + constants.BANG + "_PEB", + layer_name=proc_layer_name, + offset=proc.Peb, + ) + return peb.ImageBaseAddress + except exceptions.InvalidAddressException: + return None + + def _check_load_address(self, proc, _, __) -> Generator[str, None, None]: + """ + Detects when the image base in the PEB, which is writable by process malware, + does not match the section base address - whose value lives in kernel memory. + Many malware samples will manipulate their image base to fool AVs/EDRs and + as a necessary part of certain hollowing techniques + """ + image_base = self._get_image_base(proc) + if image_base is not None and image_base != proc.SectionBaseAddress: + yield "The ImageBaseAddress reported from the PEB ({:#x}) does not match the process SectionBaseAddress ({:#x})".format( + image_base, proc.SectionBaseAddress + ) + + def _check_exe_protection( + self, proc, vads: Dict[int, VadData], __ + ) -> Generator[str, None, None]: + """ + Legitimately mapped application executables and DLLs + will have a VAD present and its initial protection will be + PAGE_EXECUTE_WRITECOPY. + Many process hollowing and code injection techniques will + unmap the real executable and/or map in executables with + incorrect permissions. + This check verifies the VAD for the application exe. + `_check_dlls_protection` checks for DLLs mapped in the process. + """ + base = proc.SectionBaseAddress + + if base not in vads: + yield "There is no VAD starting at the base address of the process executable ({:#x})".format( + base + ) + elif vads[base].protection != "PAGE_EXECUTE_WRITECOPY": + yield "Unexpected protection ({}) for VAD hosting the process executable ({:#x}) with path {}".format( + vads[base].protection, base, vads[base].path + ) + + def _check_dlls_protection( + self, _, vads: Dict[int, VadData], dlls: Dict[int, DLLData] + ) -> Generator[str, None, None]: + for dll_base in dlls: + # could be malicious but triggers too many FPs from smear + if dll_base not in vads: + continue + + # PAGE_EXECUTE_WRITECOPY is the only valid permission for mapped DLLs and .exe files + if vads[dll_base].protection != "PAGE_EXECUTE_WRITECOPY": + yield "Unexpected protection ({}) for DLL in the PEB's load order list ({:#x}) with path {}".format( + vads[dll_base].protection, dll_base, dlls[dll_base].path + ) + + def _generator(self, procs): + checks = [ + self._check_load_address, + self._check_exe_protection, + self._check_dlls_protection, + ] + + for proc in procs: + # smear and/or terminated process + dlls = self._get_dlls_map(proc) + if len(dlls) < 3: + continue + + vads = self._get_vads_data(proc) + if len(vads) < 5: + continue + + proc_name = utility.array_to_string(proc.ImageFileName) + pid = proc.UniqueProcessId + + for check in checks: + for note in check(proc, vads, dlls): + yield 0, ( + pid, + proc_name, + note, + ) + + def run(self): + filter_func = pslist.PsList.create_pid_filter(self.config.get("pid", None)) + kernel = self.context.modules[self.config["kernel"]] + + return renderers.TreeGrid( + [ + ("PID", int), + ("Process", str), + ("Notes", str), + ], + self._generator( + pslist.PsList.list_processes( + context=self.context, + layer_name=kernel.layer_name, + symbol_table=kernel.symbol_table_name, + filter_func=filter_func, + ) + ), + )