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PyWMIPersistenceFinder.py
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PyWMIPersistenceFinder.py
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#!/usr/bin/env python
#
# PyWMIPersistenceFinder.py
# Version 1.1
#
# Author:
# David Pany - Mandiant (FireEye) - 2017
# Twitter: @DavidPany
# Please send comments, bug reports, and questions to @DavidPany
# or push changes directly to GitHub
#
# Usage:
# PyWMIPersistenceFinder.py <OBJECTS.DATA file>
#
# The output is text based in the following format for each binding:
# <consumer name>-<filter name>
# <optional notes>
# Consumer: <consumer name><consumer execution details>
# Filter: <filter name><filter listener details>
#
# Execution time:
# Execution time has been reported from 10 seconds to 5 minutes depending on input size.
#
# Description:
# PyWMIPersistenceFinder.py is designed to find WMI persistence via FitlerToConsumerBindings
# solely by keyword searching the OBJECTS.DATA file without parsing the full WMI repository.
#
# In testing, this script has found the exact same data as python-cim's
# show_FilterToConsumerBindings.py without requiring the setup. Only further testing will
# indicate if this script misses any data that python-cim can find.
#
# In theory, this script will detect FilterToConsumerBindings that are deleted and remain
# in unallocated WMI space, but I haven't had a chance to test yet.
#
# Terms:
# Event Filter:
# Basically a condition that WMI is waiting for
#
# Event Consumer:
# Basically something that will happen such as script/file execution
#
# Filter To Consumer Binding:
# Structure that says "When filter condition happens, execute consumer"
#
# Changes:
# 1.1 - removed newline characters for regex matching
# - enhanced txt output for readability
#
# Future Improvements:
# [ ] Implement named regex groups for clarity
# [ ] Add CSV output option
# [ ] Add input option for a directory of objects.data files
#
# References:
# https://github.com/fireeye/flare-wmi/tree/master/python-cim
# https://www.fireeye.com/content/dam/fireeye-www/global/en/current-threats/pdfs/wp-windows-management-instrumentation.pdf
#
# License:
# Copyright (c) 2017 David Pany
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
from __future__ import print_function
import sys
import re
import string
PRINTABLE_CHARS = set(string.printable)
def main():
"""Main function for everything!"""
print("\n Enumerating FilterToConsumerBindings...")
#Read objects.data 4 lines at a time to look for bindings
objects_file = open(sys.argv[1], "rb")
current_line = objects_file.readline()
lines_list = [current_line]
current_line = objects_file.readline()
lines_list.append(current_line)
current_line = objects_file.readline()
lines_list.append(current_line)
current_line = objects_file.readline()
lines_list.append(current_line)
#Precompiled match objects to search each line with
event_consumer_mo = re.compile(r"([\w\_]*EventConsumer\.Name\=\")([\w\s]*)(\")")
event_filter_mo = re.compile(r"(_EventFilter\.Name\=\")([\w\s]*)(\")")
#Dictionaries that will store bindings, consumers, and filters
bindings_dict = {}
consumer_dict = {}
filter_dict = {}
while current_line:
# Join all the read lines together (should always be 4) to look for bindings spread over
# multiple lines that may have been one page
potential_page = " ".join(lines_list)
# Look for FilterToConsumerBindings
if "_FilterToConsumerBinding" in potential_page:
if (
re.search(event_consumer_mo, potential_page) and
re.search(event_filter_mo, potential_page)):
event_consumer_name = re.search(event_consumer_mo, potential_page).groups(0)[1]
event_filter_name = re.search(event_filter_mo, potential_page).groups(0)[1]
#Add the consumers and filters to their dicts if they don't already exist
#set() is used to avoid duplicates as we go through the lines
if event_consumer_name not in consumer_dict:
consumer_dict[event_consumer_name] = set()
if event_filter_name not in filter_dict:
filter_dict[event_filter_name] = set()
#Give the binding a name and add it to the dict
binding_id = "{}-{}".format(event_consumer_name, event_filter_name)
if binding_id not in bindings_dict:
bindings_dict[binding_id] = {
"event_consumer_name":event_consumer_name,
"event_filter_name":event_filter_name}
# Increment lines and look again
current_line = objects_file.readline()
lines_list.append(current_line)
lines_list.pop(0)
# Close the file and look for consumers and filters
objects_file.close()
print(" {} FilterToConsumerBinding(s) Found. Enumerating Filters and Consumers..."
.format(len(bindings_dict)))
# Read objects.data 4 lines at a time to look for filters and consumers
objects_file = open(sys.argv[1], "rb")
current_line = objects_file.readline()
lines_list = [current_line]
current_line = objects_file.readline()
lines_list.append(current_line)
current_line = objects_file.readline()
lines_list.append(current_line)
current_line = objects_file.readline()
lines_list.append(current_line)
while current_line:
potential_page = " ".join(lines_list).replace("\n", "")
# Check each potential page for the consumers we are looking for
if "EventConsumer" in potential_page:
for event_consumer_name, event_consumer_details in consumer_dict.iteritems():
# Can't precompile regex because it is dynamically created with each consumer name
if "CommandLineEventConsumer" in potential_page:
consumer_mo = re.compile("(CommandLineEventConsumer)(\x00\x00)(.*?)(\x00)(.*?)"
"({})(\x00\x00)?([^\x00]*)?"
.format(event_consumer_name))
consumer_match = re.search(consumer_mo, potential_page)
if consumer_match:
noisy_string = consumer_match.groups()[2]
consumer_details = "\n\t\tConsumer Type: {}\n\t\tArguments: {}".format(
consumer_match.groups()[0],
filter(lambda event_consumer_name: event_consumer_name in
PRINTABLE_CHARS, noisy_string))
if consumer_match.groups()[5]:
consumer_details += "\n\t\tConsumer Name: {}".format(consumer_match.groups()[5])
if consumer_match.groups()[7]:
consumer_details += "\n\t\tOther: {}".format(consumer_match.groups()[7])
consumer_dict[event_consumer_name].add(consumer_details)
else:
consumer_mo = re.compile(
r"(\w*EventConsumer)(.*?)({})(\x00\x00)([^\x00]*)(\x00\x00)([^\x00]*)"
.format(event_consumer_name))
consumer_match = re.search(consumer_mo, potential_page)
if consumer_match:
consumer_details = "{} ~ {} ~ {} ~ {}".format(
consumer_match.groups()[0],
consumer_match.groups()[2],
consumer_match.groups()[4],
consumer_match.groups()[6])
consumer_dict[event_consumer_name].add(consumer_details)
# Check each potential page for the filters we are looking for
for event_filter_name, event_filter_details in filter_dict.iteritems():
if event_filter_name in potential_page:
# Can't precompile regex because it is dynamically created with each filter name
filter_mo = re.compile(
r"({})(\x00\x00)([^\x00]*)(\x00\x00)".format(event_filter_name))
filter_match = re.search(filter_mo, potential_page)
if filter_match:
filter_details = "\n\t\tFilter name: {}\n\t\tFilter Query: {}".format(
filter_match.groups()[0],
filter_match.groups()[2])
filter_dict[event_filter_name].add(filter_details)
current_line = objects_file.readline()
lines_list.append(current_line)
lines_list.pop(0)
objects_file.close()
# Print results to stdout. CSV will be in future version.
print("\n Bindings:\n")
for binding_name, binding_details in bindings_dict.iteritems():
if (
"BVTConsumer-BVTFilter" in binding_name or
"SCM Event Log Consumer-SCM Event Log Filter" in binding_name):
print(
" {}\n (Common binding based on consumer and filter names,"
" possibly legitimate)".format(binding_name))
else:
print(" {}".format(binding_name))
event_filter_name = binding_details["event_filter_name"]
event_consumer_name = binding_details["event_consumer_name"]
# Print binding details if available
if consumer_dict[event_consumer_name]:
for event_consumer_details in consumer_dict[event_consumer_name]:
print(" Consumer: {}".format(event_consumer_details))
else:
print(" Consumer: {}".format(event_consumer_name))
# Print details for each filter found for this filter name
for event_filter_details in filter_dict[event_filter_name]:
print("\n Filter: {}".format(event_filter_details))
print()
# Print closing message
print("\n Thanks for using PyWMIPersistenceFinder! Please contact @DavidPany with "
"questions, bugs, or suggestions.\n\n Please review FireEye's whitepaper "
"for additional WMI persistence details:\n https://www.fireeye.com/content/dam"
"/fireeye-www/global/en/current-threats/pdfs/wp-windows-management-instrumentation.pdf")
if __name__ == "__main__":
main()