# This file is Copyright 2023 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 Iterable, List, Tuple
from volatility3.framework import interfaces, renderers
from volatility3.framework.configuration import requirements
from volatility3.framework.renderers import format_hints
from volatility3.plugins import yarascan
from volatility3.plugins.linux import pslist
vollog = logging.getLogger(__name__)
[docs]
class VmaYaraScan(interfaces.plugins.PluginInterface):
"""Scans all virtual memory areas for tasks using yara."""
_required_framework_version = (2, 4, 0)
_version = (1, 0, 3)
[docs]
@classmethod
def get_requirements(cls) -> List[interfaces.configuration.RequirementInterface]:
# create a list of requirements for vmayarascan
vmayarascan_requirements = [
requirements.ListRequirement(
name="pid",
element_type=int,
description="Process IDs to include (all other processes are excluded)",
optional=True,
),
requirements.PluginRequirement(
name="pslist", plugin=pslist.PsList, version=(4, 0, 0)
),
requirements.PluginRequirement(
name="yarascan", plugin=yarascan.YaraScan, version=(2, 0, 0)
),
requirements.VersionRequirement(
name="yarascanner", component=yarascan.YaraScanner, version=(2, 0, 0)
),
requirements.ModuleRequirement(
name="kernel",
description="Linux kernel",
architectures=["Intel32", "Intel64"],
),
]
# get base yarascan requirements for command line options
yarascan_requirements = yarascan.YaraScan.get_yarascan_option_requirements()
# return the combined requirements
return yarascan_requirements + vmayarascan_requirements
def _generator(self):
# use yarascan to parse the yara options provided and create the rules
rules = yarascan.YaraScan.process_yara_options(dict(self.config))
sanity_check = 1024 * 1024 * 1024 # 1 GB
# filter based on the pid option if provided
filter_func = pslist.PsList.create_pid_filter(self.config.get("pid", None))
for task in pslist.PsList.list_tasks(
context=self.context,
vmlinux_module_name=self.config["kernel"],
filter_func=filter_func,
):
# attempt to create a process layer for each task and skip those
# that cannot (e.g. kernel threads)
proc_layer_name = task.add_process_layer()
if not proc_layer_name:
continue
# get the proc_layer object from the context
proc_layer = self.context.layers[proc_layer_name]
max_vma_size = 0
vma_maps_to_scan = []
for start, size in self.get_vma_maps(task):
if size > sanity_check:
vollog.debug(
f"VMA at 0x{start:x} over sanity-check size, not scanning"
)
continue
max_vma_size = max(max_vma_size, size)
vma_maps_to_scan.append((start, size))
if not vma_maps_to_scan:
vollog.warning(f"No VMAs were found for task {task.tgid}, not scanning")
continue
scanner = yarascan.YaraScanner(rules=rules)
scanner.chunk_size = max_vma_size
# scan the VMA data (in one contiguous block) with the yarascanner
for start, size in vma_maps_to_scan:
for offset, rule_name, name, value in scanner(
proc_layer.read(start, size, pad=True), start
):
yield 0, (
format_hints.Hex(offset),
task.tgid,
rule_name,
name,
value,
)
[docs]
@classmethod
def get_vma_maps(
cls,
task: interfaces.objects.ObjectInterface,
) -> Iterable[Tuple[int, int]]:
"""Creates a map of start/end addresses for each virtual memory area in a task.
Args:
task: The task object of which to read the vmas from
Returns:
An iterable of tuples containing start and end addresses for each descriptor
"""
if task.mm:
for vma in task.mm.get_vma_iter():
vm_size = vma.vm_end - vma.vm_start
yield (vma.vm_start, vm_size)
[docs]
def run(self):
return renderers.TreeGrid(
[
("Offset", format_hints.Hex),
("PID", int),
("Rule", str),
("Component", str),
("Value", bytes),
],
self._generator(),
)